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Section 10: Heating Operation

In most of our discussion in the previous sections, emphasis has been given to the cooling

operation whereby the mini chiller produces chilled water. The heat pump version of the mini
chiller (designated with "R" at the end of the model name, e.g. AC 50AR, AC 125BR, AC 80CR
can operate both under the cooling mode and heating mode, i.e. it can produce either chilled
water or hot water. The heating cycle is run during the cold, winter months. Operation of the
heating cycle is accomplished by reversing the refrigerant flow in the circuit with a 4-way valve. By
doing so, the BPHE becomes the condenser which rejects the heat absorbed from the ambient air
into the water. The mini chiller has been designed with a rated water entering and leaving
temperatures of

40°C and 45°C

respectively in the heating cycle.

(Compare rating for the cooling cycle at 12°C and 7°C for entering and leaving temperatures)
The maximum allowable entering water temperature is 50°C, i.e. corresponding to a
leaving temperature of 55°C.

The mini chiller has also been designed to operate the heating cycle with an ambient
temperature range of -5°C to 15°C.

Because of the higher water temperature, several precautions must be taken into
consideration when using this system:

Application considerations:

1. In multiple chiller installation, all the chillers must either run in the cooling mode or heating
mode. We cannot have a few units running cooling cycle while the rest running heating cycle
because this may damage the compressor as a result of overloading.

2. In the same manner, in multiple fan coil units installation with a single mini chiller, the wiring of
the system must be in such a way to have all the fan coil units either in cooling mode or heating
mode.

3. Do not use PVC pipes for such heating systems. PVC is OK for chilled water but long term usage
with hot water will soften and weaken the material. Most of these pipes will exhibit sagging in
between supports after some time.
It is recommended that black steel or copper pipes to be used instead.

4. Any gaskets, sealants or insulation material used in the piping system must able to withstand
temperatures of at least 60°C without degradation of their physical properties.

5. Recheck again the pipe insulation thickness which has been sized for the cooling cycle to
prevent condensation. In the heating cycle, the insulation thickness must be sufficient to have a
safe handling surface temperature (e.g. 30 to 35°C).

Section 10

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Содержание AC 40A

Страница 1: ...AM MAC ...

Страница 2: ...120 11 Electrical Wiring Control 121 140 12 Flow Switch 141 145 13 System Balancing 146 148 14 Chiller Shut Down 149 150 Appendix Appendix 1 19 37 Pages Copyright 2003 by McQuay International All rights reserved This publication is strictly confidential and is meant for DISTRIBUTORS of McQuay International only No part of this publication may be reproduced or distributed in any form or by any mean...

Страница 3: ...t and multi split direct expansion systems i e they are more environmental friendly 3 There is no necessity to use cooling towers 4 No refrigerant is used in the occupied space 5 The usage of water as the cooling medium allows for excellent load variability with minimal system complexity as against equivalent VRV systems 6 Ability to have long piping distances A water hydronic system can be classi...

Страница 4: ...pansion device condenser and evaporator A brazed plate heat exchanger BPHE is used as the evaporator to produce the chilled water A built in water tank is also provided in the mini chiller to act as a buffer storage See next page For integration both the expansion tank and pump are incorporated together into the mini chiller Hence the schematic diagram of the system becomes as follows Introduction...

Страница 5: ...ion design guidelines will also be discussed Selection criteria of piping valve pump and other equipment are also given Examples of such complete installations are as shown in the following pages This manual will give some technical information and details on how such installations are designed and done at site In general there are three series of mini chillers available a A series from 30 000 Btu...

Страница 6: ... discharge air Do not block any air passage in and out of the units Please refer to the corresponding Technical Manual for further information The chiller unit must be placed on a firm surface e g concrete flooring slab or plinth Due to space consideration the chiller may be mounted onto a steel bracket which is secured to a firm surface e g brick wall concrete wall or a steel structure concrete f...

Страница 7: ...t by using studs wall plugs or bolts nuts at the four 4 mounting holes located at the base plate of the chiller The weight of the chiller unit and the water pipe connections are not sufficient to prevent unit movement should any sudden impact or strong vibrations occur in the unit Failure to do so may cause the water pipes to deform and break It is further recommended that rubber isolation pads 1 ...

Страница 8: ...igerant Water B series A series In some special installations whereby the available space especially the height is not sufficient to install the chiller it is possible to to detach these two compartments and install them side by side This is especially useful when there are multiple units which are stacked together with a steel bracket Bracket Hydraulic kit Water pipes Refrigerant pipe connection ...

Страница 9: ...gth between the two compartments Always choose the shortest path Long piping will cause high pressure drops and reduces the capacity of the system Use the following recommendations Maximum elevation m AC 040A 10 AC 050A 10 AC 058A 10 b It is possible to have the hydraulic kit higher or lower than the refrigerant compartment Do not allow excessive elevation between these two compartments Use the fo...

Страница 10: ...h the unit to collect any condensate water from the chiller unit This is especially so for the heat pump versions where water will condense on the heat exchanger coil during the heating mode Further more a lot of water will flow out during the defrost cycle Such external drain pans are needed when the chiller units are installed inside a plant room where it is not appropriate for the floor to be w...

Страница 11: ...ble space for installation e g the dimensions of the plant room c the economics of installation d loading capability requirements The general rule of thumb in designing and determining the piping circuit network is KEEP IT SIMPLE The more extensive a pipe network is the more complex it is and it becomes more difficult to analyse and control In general there are 4 types of this pipe configuration 1...

Страница 12: ...ity in each fan coil an air vent is required for each fan coil iii Higher installation cost iv Water entering temperature for each fan coil is different i e it gets higher further away from the source However both the series and diverting circuits are seldom used in hydronic systems The more commonly used are the parallel circuits because they allow the same water temperature to be available to al...

Страница 13: ...ancing is required to provide adequate water flow rate for each fan coil Nevertheless the cost of installation is lower compared with the reverse return configuration due to the shorter pipe length needed Therefore this method is more economical for installation of fan coils with different pressure drops and balancing valves are used This method is also suitable for open system applications whereb...

Страница 14: ... coil units have the same or nearly the same pressure drops Another advantage of this reverse return system is a reduction of the working pressure drop across any balancing valves used for the fan coil units However such a system is not recommended for high rise buildings because of the vertical weight of the extra piping required In such instances it may be more practical to use direct return sys...

Страница 15: ...rn piping Instead only the return header is in reverse whereas the supply to the individual fan coils are in direct configuration direct supply reverse return This method will have the advantage of lower installation cost with some benefits of a better water balanced system Balancing valves are required for each fan coil unit for proper flow balancing Section 2 Page 13 ...

Страница 16: ... operation multiple secondary pumps supplying chilled water to several zones The water volume in the tank can also be sized to act as a storage to provide cold water to the fan coil units By doing so the chiller may be cycled off for longer periods of time hence saving energy costs However since this is an open system there is a higher chance of air entering the water Care must also be taken to en...

Страница 17: ...his booster pump to be installed as a primary secondary system as follows A B Primary pump in chiller unit Secondary booster pump Bypass loop Load More than one secondary pumps can be installed together e g to serve several zones There are two drawbacks to this system a Cost additional two or more pumps are required b The bypass chilled water is sent back to the chiller unused Keep the bypass loop...

Страница 18: ...he capacity of primary pump secondary pump there will be a nett flow up the loop from B to A Thus tee A becomes a mixing tee and tee B becomes a diverging tee Then the water temperature entering the load will be in between the water temperature leaving the chiller and the water temperature entering the chiller There may be installations using pumps in series to boost the head pressure But this is ...

Страница 19: ...illers will switch off one by one Generally the header pipe size is larger than the supply and return pipes e g one or two size larger This is to have a low pressure drop along the header Check valves are usually located along each chiller supply pipe to prevent back flush of water once the chiller is switched off Such back flow may damage the water pump However this method has several drawbacks a...

Страница 20: ...e header pipe This will help to balance the water distribution between the left and right sides of the header If the common pipe is at one end of the header water from the branches at the other end of the header will find more difficulty to flow into the common pipe Balancing valves must be installed at each supply branch to ensure adequate water flow rate through each chiller unit 2 Primary Secon...

Страница 21: ...sure requirements of the loads Because of this secondary pump the sequencing of the chillers will not affect the water supply to the load when any of the primary pumps switches off Several secondary pumps can also be installed to the bypass loop to serve several zones This creates flexibility of installation The only drawback to this method is cost The piping network is more extensive and addition...

Страница 22: ...dual pipe circuit There is no cross flow among each of them This has been achieved with the common tank which acts as a buffer storage tank Therefore there is no need of check valves Normal globe valves will suffice to ensure proper water flow through each chiller Usually the tank is at a higher elevated position to allow gravity feed of water to the chillers and pumps This method is most expansiv...

Страница 23: ...aster at the tee nearest to the main supply lines due to lower friction Therefore proper balancing to ensure sufficient distribution to each chiller is vital A First In Last Out arrangement between the supply and return lines may be useful to reduce the problem of distribution 5 Another variation to the primary secondary system mentioned in 2 above is to use an auxillary tank to replace the by pas...

Страница 24: ...o a large single fan coil unit Each chiller will serve one of the multiple circuits of the heat exchanger coil in the fan coil unit There are two ways to install the pipe circuits for this system a Individual Circuiting b Common Header CIRCUIT 1 CIRCUIT 2 CIRCUIT 3 CHILLER 1 CHILLER 2 CHILLER 3 CIRCUIT 1 CIRCUIT 2 CIRCUIT 3 Section 2 Page 22 ...

Страница 25: ...e also needed for each chiller for water balancing All the pumps will operate in parallel and a higher water pressure drop is expected Furthermore balancing valves are also required in each circuit of the fan coil unit for proper balancing of the entire coil Nevertheless if any one of the chiller is OFF the second method will always allow an even water distribution to the whole heat exchanger in t...

Страница 26: ...pipe is lower than the pressure in the return pipe water will not enter the system Rather switch off the pump and allow the mains pressure to fill the system In view of this it is necessary to install a check valve along the make up supply pipe to prevent back flow out of the system Other equipment which can be installed optional along the make up supply pipe a Pressure gauge b Safety relief valve...

Страница 27: ...c air vent valve A high pressure drop along such pipe network may result in the return water to have a negative pressure i e suction vacuum pressure in the buffer tank Due to the mechanism of the air vent air will be drawn into the buffer tank itself This in turn will cause the pump to be air locked A symptom of such condition is that air will always be purged out of the tank when we manually open...

Страница 28: ...pipe connections 1 A Series The pipe connections are on the right hand side of the unit when facing the fan blade 2 B Series The pipe connections are on the same side as the control box compartment Water inlet Water outlet Water inlet Water outlet Section 2 Page 26 ...

Страница 29: ...3 C Series The pipes can be connected either from the left or right side of the unit with respect to the compartment doors Water inlet Water outlet Section 2 Page 27 ...

Страница 30: ...able Always calculate the friction losses in the system and compare this with the capability of the water pump in the chiller unit See Section 4 1 Black Steel Pipes The black steel pipes are the most commonly used in chiller installations It is relatively cheap and by far the strongest among the 3 types mentioned above However these pipes are heavier and requires more extensive work to join and in...

Страница 31: ...f their resistance to corrosion and ease of installation The pipes are light and ductile However the cost of these pipes are higher compared with steel pipes generally by 3 5 times The sizes of these copper pipes are defined by the ASTM American Society for Testing and Materials standard B88 for water and drain services See Appendix 2 There is also another ASTM standard B280 which specifies the si...

Страница 32: ...1 8062 standard Therefore use back pipes and fittings with the same standard when running pipes from the chiller to the fan coil units It is recommended that pipes with pressure rating of PN16 16 bar working pressure to be used See Appendix 3 Do not use PVC pipes manufactured to other standard specifications e g BS 3505 3506 as the fittings will not match with those used in the chiller The pipe wa...

Страница 33: ...tings for weld joining may also be used The following standards are applicable for these fittings ASME B16 9 ASME B16 11 ASME B16 28 and ASME B1 20 1 Internal thread Tee joint Internal thread 90º elbow Internal Page 31 Section 3 thread Reducer 45º elbow are also available but not commonly used unless necessary A tee joint can either be a flow mixing or flow diverging point depending on the design ...

Страница 34: ...ittings e g an elbow with a reducer nipple External thread connector Used for joining two lengths of pipes together Internal thread Union coupling Used for joining two lengths of pipes together Made up of two halves each screwed into a pipe end Both are then joined with a locking nut in between ...

Страница 35: ...rfaces of both flanges This method is not recommended for the small pipe size used for the mini chiller The fittings for weld joining are very similar to those mentioned above i e they do not come with the thread portion They may be butt welded or socket welded BUTT SOCKET Section 3 Page 33 ...

Страница 36: ... expander tooling and the end of the other pipe is inserted into the expanded end The joint is then brazed together see Appendix 4 for expansion dimensions Similarly fittings are available for such brazing joints 90º elbow expanded end reducer Usually the pipe outer diameter will insert into the reducer inside diameter tee joint expanded end some may come with reducer end Section 3 Page 34 ...

Страница 37: ...ed with this method However the larger the pipe size the more difficult this will become expanded end Pipe bend CAUTION Do not bend the pipes with hands This will cause the pipe to collapse at the bending portion Use the suitable pipe bending tool Manual hand benders allows a maximum size of 3 4 Pipes up to 1 3 8 can still be bended by using bending machine NOTE During brazing of copper to copper ...

Страница 38: ...y the fittings have mounting rings which are slipped onto the copper pipes The ring is then pushed against the fitting internal surface and a locking nut is used to hold the assembly together 90 elbow Locking nut mounting ring 90 elbow with threaded ends normal elbow female thread with steel pipe fittings male thread Such elbows are for special applications For example connection with steel pipe f...

Страница 39: ...e steel type Used for connecting two pipe together with flexibility of easy connection and dismantling Some have threaded ends others with compression fitting ends In some installations the copper pipes are brazed with silver flux onto each half of the union and then connected together with the locking nut NOTE Brazing of copper to brass requires filler rods with 34 silver Section 3 Page 37 ...

Страница 40: ...d able to withstand higher pressures and temperatures Generally these fittings are the cheapest and easiest to install 90 elbow With the threaded end some elbows it is also possible to have threaded connect with a steel pipe ends or steel fitting tee joints connector Used to connect two PVC Pipes together with solvent cement Section 3 Page 38 ...

Страница 41: ... pipe or tank union locking nut the two halves of the union Similar to the steel and copper versions these unions enable easy connection and dismantling of two PVC pipe ends The PVC pipes are joined to the two halves by using solvent cement and then they are assembled together with the locking nut reducer Section 3 Page 39 ...

Страница 42: ...tee connection with opposing flow directions turbulence occurs here and causes high friction losses b Encourage eduction out of a bypass tee branch return water the higher velocity of flow in the run of the pulls water our of the tee branch bypass branch bypass branch Do not allow the higher return water velocity to ram into the tee joint This may cause a backflow into the bypass branch backflow o...

Страница 43: ...f the system thereby enabling easy maintenance and repair of that component b To regulate the water flow rate through the system c To divert or mix flow directions optimizing the water temperature in the system d To relieve or regulate pressure e To prevent backflow Valves are constructed to withstand a specific range of temperature pressure corrosion and mechanical stress Careful selection of the...

Страница 44: ...ovement of the disc is parallel to the flow direction used for pipe diameters up to 300mm used for throttling duty where positive shutoff is required 2 Gate Valve Flow is controlled by means of a wedge disc fitting against seating faces Gate movement is pependicular to the flow direction has straight through openings as large as the full bore of the pipe this type of valves are intended to be full...

Страница 45: ...th smaller pipe diameters up to 75mm 4 Butterfly Valve This valve has a cylindrical body with an internal rotatable disc serving as the fluid flow regulating device This disc s axis of rotation is the valve stem and it is pependicular to the flow direction A 90 turn will change the operation from fully open to fully closed has low pressure drops fast operation of valve may be used for throttling d...

Страница 46: ...e through the valve can be determined The valve handwheel will have a setting scale to determine the amount of valve opening This is useful during field commissioning and balancing Generally the internal construction is similar to a globe valve It is more costly than the conventional throttling valves and it is only used in systems where proper and accurate balancing is required Normally connected...

Страница 47: ...en the coil is either energized or de energized Such valves are generally used for pipe sizes up to 50mm only They are suitable for small fan coil units which require water shut off when the fan coil is switched off solenoid coil b Electric Motorised Valve The actuator has a built in motor to produce a rotary motion By using gears cams or linkages the valve stem will be opened or closed Usually th...

Страница 48: ...gm will push the valve stem An opposing spring force on the valve stem will also resist this movement Therefore by varying this air pressure valve positioning can be achieved For this to work an external pneumatic converter positioner must be used to regulate the air pressure A thermostat may be used together for such a purpose This cost for this type of valves is also high upper housing diaphragm...

Страница 49: ...d double seated For most applications the single seated type will suffice In this type there is only one valve seat and one plug disc to clsoe against the flow However for applications with higher operating pressures the double seated types may be used attachment to actuator Water In Water Out In the three way valve three ports are available Depending on the application these can be configured as ...

Страница 50: ...as constant flow variable It is recommended that the 3 way valve to be configured as a diverting valve instead of a mixing valve This is because when the fan coil unit is OFF cold water will not enter into the heat exchanger with the valve diverting the water away to the return line Unlike the mixing valve even though the valve may be closed cold water can still enter into the heat exchanger and c...

Страница 51: ... solenoid valves i e FAN COIL UNIT 1 FAN COIL UNIT 2 Mini Chiller 2 way solenoid 2 way solenoid T there will not be any water flow through the system when the fan coils are not in use However the chiller pump is still running Therefore the water pressure built up in the piping may cause damage to the water pump or to the valves themselves valve stem lifting Usage of 2 way valves will require addit...

Страница 52: ... control 2 way valve will be off It is possible to run a line from the thermostat to the chiller remote switch whereby when the thermostat cuts off the chiller unit and the pump will also switch off See Section 11 on Electrical Wiring Control for more details However the disadvantage with this method is that the chiller cycle on off more frequently and the water supply temperature will fluctuate u...

Страница 53: ...he supply water is by passed around the load coil energy is wasted This will cause the chiller to cycle on off more frequent as the return water temperature becomes lower Therefore in terms of energy efficiency applications with 2 way valves are better Section 3 Page 51 ...

Страница 54: ... or vertical piping 2 lift check valve only for horizontal piping installation Swing check valve Lift check valve b Plug Cock Plug Valve This type of valve is also used for throttling duty It is less expansive compared with the globe valve or balancing valve The setting also cannot be tampered with as easily as the globe valve Valve stem without handwheel Use a spanner or wrench to open and close ...

Страница 55: ... system which may cause damage Normally this is used when the system is running hot water mini chiller in heating mode reverse cycle in a closed piping The hotter the water temperature the higher is the pressure due to expansion Such valves are also useful for protection against sudden pressure shocks e g water hammering and overpressuring from water fill system If the system is with an open pipin...

Страница 56: ...tall another air vent at the highest position of the piping network to ensure that the pump performance do not deteriorates Such air vents are also useful during commissioning and system start ups to release any air trapped in the piping system Always install the valve in a vertical position on top of a tank or pipe pipe air vent air vent CORRECT INCORRECT Under normal condition water will enter i...

Страница 57: ... a strainer on the water inlet pipe into the chiller to protect the internal water pump strainer CHILLER water outlet water inlet Do not install strainer on the water outlet pipe as the water velocity is higher Install the strainer with the filter element in a downward position This is to facilitate easy flushing during periodic cleaning allow sufficient space to remove filter strainer with filter...

Страница 58: ...e with a socket welded onto the pipe or a tee joint connection g Thermometer Glass thermometers are installed on the inlet and outlet pipes of either the chiller unit or fan coil units This is e m e differential to determine the capacity performance Usually these thermometers are installed together with the pressure gauges In r threaded joint welded joint threaded thermomete socket Flow joint tee ...

Страница 59: ...lowing stream of water If the thermometer is installed too high up the connecting socket the bulb will measure the temperature of stagnant water in the socket thermometer too high up stagnant water Thermometer bulb measuring correct water flow temperature CORRECT INCORRECT Section 3 Page 57 ...

Страница 60: ...What is the piping connection method to the valve threaded flanged Most of the above mentioned information may be obtained from the valve catalogs provided by the valve manufacturers In sizing the valve the general accepted method is by means of the Cv flow coefficient Different valves will have different Cv values Formula Q Cv p Definition The Cv rating of any valve is the amount of water Q GPM a...

Страница 61: ... Pressure losses along piping works from A to B 4 6 feet Pressure drop across 2 gate valves coil heat exchanger 6 feet Therefore the control 3 way valve should have a pressure drop of at least 2 4 6 6 21 2 feet 9 2 psi Conversion 1 psi 2 309 feet water If the flow rate through the branch is 6 GPM what valve Cv should be used Refering to the graph in Appendix 5 the Cv should be 2 Therefore a 3 way ...

Страница 62: ...ee types 1 Quick Opening The valve shows a quick increase of flow for a small increase of opening But as it reaches the open position the rate at which the flow increases per movement of the opening reduces 2 Linear This valve produces equal rate of flow increase per equal rate of opening 3 Equal Percentage This type of valve produces an exponential flow increase as the valve opens up The term equ...

Страница 63: ...alve opening Flow rate For automatic on off valves e g solenoid 2 way 3 way the selection is easier Generally use the same size as the pipe size with a low pressure drop e g 2 5 psig fully open Using a smaller size with pipe reducers and adaptors for economic reasons is possible but check for excessive pressure losses which will reduce the pump performance Section 3 Page 61 ...

Страница 64: ...threaded or welded joints will require unions to permit easy removal for servicing or replacement Unions are usually located between each gate valve and the equipment Unions are also place before and after the control valve and in the branch of the 3 way valve If flange joints are used the need for unions is eliminated c Locate the control valve in between the gate valve and the equipment to permi...

Страница 65: ...P T P T Typical Mini Chiller Piping Installation Water supply Water return CHILLER 1 1 4 connector Make up water from main supply or water tank RETURN SUPPLY gauge cock FAN COIL UNIT Typical Fan Coil Unit Installation a Horizontal installation Section 3 Page 63 ...

Страница 66: ...e valve FAN COIL 1 FAN COIL 2 FAN COIL 3 T T 3 way diverting valve b Vertical Installation T T o Multiple Fan Coil Unit Installation T All three fan coil units to serve one area with a common thermostat When temperature has reached set point thermostat will send signal to 3 way valve to divert water away ...

Страница 67: ...e valve Make up water Return Supply Multiple Chiller Installation Common Header Globe valve will be used to balance the flow rate through each chiller unit Additional gate valves may be installed along the main supply and return lines to isolate the entire chiller assembly ...

Страница 68: ... glove valve secondary pump RETURN CHILLER tee joint Remember Do not encourage bullheading here Water Tank Installation Open System RETURN RETURN TANK adaptor c w nubber gasket To external pump CHILLER SUPPLY Section 3 Page 66 ...

Страница 69: ...pe length D pipe internal diameter v mean velocity g acceleration due to gravity The friction factor is a function of the roughness parameter e which in turn depends on the pipe material e g steel copper PVC and the Reynolds number Re Re D v ρ µ where ρ density µ dynamic viscosity Generally the friction losses are presented in graphical form for various pipe material See attached charts for steel ...

Страница 70: ... pressure drops turbulence cavitation and flashing If precautions are taken to eliminate air and turbulences higher velocities up to 8 fps are acceptable 3 The minimum velocity in the pipe should be 1 5 2 fps to allow air entrained in the water to be carried to separation units e g expansion tanks locations of lowest pressure for venting Taking into consideration 2 and 3 above it is recommended th...

Страница 71: ...7 0 89 1 43 2 47 AC 50A 8 9 1 19 1 91 3 30 AC 58A 11 1 1 48 2 38 4 12 AC 75B 17 8 2 37 3 80 6 59 AC100B 22 2 2 97 4 75 8 24 AC125B 27 7 3 71 5 94 10 30 AC80C 17 5 2 34 3 75 6 50 AC100C 20 8 2 78 4 46 7 72 AC120C 26 7 3 57 5 72 9 92 AC150C 31 7 4 24 6 79 11 78 It is not recommended to install these units with 1 pipe size Section 4 Page 69 ...

Страница 72: ... See attached tables Appendix 7 An alternative method was published in the ASHRAE Handbook Fundamentals for calculating the equivalent pipe length of tee joints A graph is used to determine the number of equivalent elbows for the various flow conditions through the tee This is then multiplied with the equivalent pipe length pressure loss for the same size elbow See Appendix 7 It must be noted that...

Страница 73: ...w switch etc All these internal losses are as tabulated below Friction loss Nominal water Model psi flow rate GPM AC 40A AR 5 4 6 7 AC 50A AR 6 4 8 9 AC 58A AR 5 7 11 1 AC 75B BR 6 0 17 8 AC 100B BR 6 5 22 2 AC 125B BR 6 6 27 7 AC 80C CR 5 9 17 5 AC 100C CR 12 5 20 8 AC 120C CR 6 4 26 7 AC 150C CR 9 9 31 7 In the same manner each fan coil unit has its own internal losses through the heat exchanger...

Страница 74: ...nch is being calculated 3 The following information must be available for calculation water flow rate GPM of each pipe branch internal friction losses of the chiller unit fan coil unit and water pump head available These information can be obtained from the product catalogs or technical manuals 4 Calculate for the branch which gives the highest friction loss This usually corresponds to the branch ...

Страница 75: ...lumetric Flowrate b Head Pressure c Input Power d Efficiency e NPSH nett positive suction head Various pump designs are available to meet different requirements Some of the common parameters which pump manufacturers use for their design are 1 Impeller Diameter Generally the larger impeller will give higher flowrate and higher head pressure 2 Number of Impellers These multiple stages will increase ...

Страница 76: ...n the mini chillers are from GRUNDFOS The models involved are Mini Chiller Model AC 40A AR CH2 30 AC 50A AR CH2 30 AC 58A AR CH2 30 AC 75B BR CH4 40 AC 100B BR CH4 40 AC 125B BR CH4 40 AC 80C CR CH4 40 AC 100C CR CH4 40 AC 120C CR CH8 40 AC 150C CR CH8 40 The impeller and all movable parts in contact with the water are made of stainless steel The pump suction and discharge chambers are made of cas...

Страница 77: ...m pressure drop we can thus determine the flow rate when the pump is running Hence we can check whether the system pipe design is suitable for a particular pump application This pump head pressure can also be measured at the pump discharge port by using a pressure gauge The above curve is for a single fixed speed pump If the pump were to operate under different power supply frequencies e g from 50...

Страница 78: ...e of 20 m This is more than sufficient to cater for the total system friction loss Therefore the pump is OK 20 m Similarly in Application Example No 2 we have a flowrate of 27 usgpm with a requirement of total friction loss of 26 4m Entering now into the pump performance curve of CH4 40 we find that at this flowrate the pump can only deliver a head pressure of 19 m 27 USGPM his is not enough for t...

Страница 79: ...s will give the operating point of the system What we have done in the Application Example No 1 and 2 is to calculate the desired design operating point of the mini chiller with that particular piping network In the first example we have found that the pump has a much higher capacity compared with the requirement System Curve 1 P system curve 2 20 system curve 1 dP pump curve 2 5 Q calculated oper...

Страница 80: ... the pump P Q curve during commissioning of the hydronic system To do so we need to measure the water pressure at the discharge port This value is quite close to the actual head pressure developed by the pump By plotting this pressure on the P Q curve we can then determine the approximate flowrate flowing through the system and compare it with the design requirement Appropriate action can then be ...

Страница 81: ...ich is equivalent to the summation of each individual pump flowrate at the operating head pressure Example Two mini chillers of the same model are connected together to a load as shown schematically simplified below header C1 Load C2 The pump in each chiller is delivering a flow of ϖ GPM Assume that the friction loss in each branch of the header pipe is the same Therefore the flow in the load will...

Страница 82: ...d P2 Therefore the pressure after the header will be P3 when the two flows combine together What happens when the two chillers C1 and C2 are of different model i e pumps of different characteristics In such instances we will still add the two curves together and we will have the pump curves as follows Head pressure pump curve C1 pump curve C2 X P1 P3 combined pump curve P2 ϖ1 ϖ2 ϖ1 ϖ2 Flowrate Of ...

Страница 83: ...mended for the mini chiller units to be installed in series This will cause problems in controlling the water temperature and may cause damage to the heat exchangers and pumps Should the need arises install the pump along the water discharge line to boost the head pressure Example The head pressure of the pump in chiller C1 is not sufficient to overcome the total friction loss to the the load Ther...

Страница 84: ...suction head pressure in excess of the vapour pressure required to prevent formation of the vapour bubbles is known as the Net Positive Suction Head Required NPSHR This NPSHR is a characteristic of a pump and is available from the manufacturer pump curves Note The NPSHR can also be defined as the frictional resistance from the pump inlet to the first impeller In order to prevent cavitation the act...

Страница 85: ...er for the actual pipe installation Example 1 A mini chiller C1 is installed with a storage tank in the following configuration Return water Storage tank 7 C H 6ft Supply water C1 The chiller operate at the following parameters Flowrate 8 USGPM 1 82 m3 hr the total suction line friction losses 2 ft the internal friction loss from the chiller inlet pipe to the pump inlet 1 6 ft The water tank is el...

Страница 86: ...nk i e the pump is used to lift up water from the tank then care must be taken to check for cavitation Suppose the tank is lower than the pump inlet then the value of Ps in equation 1 will be negative Rearranging the equation 1 Ps Pa Pvp Pf NPSHA Therefore in the above example for the same flowrate of 1 8 m3 hr and a NPSHR of 3 28 ft we can calculate what the maximum height is which the pump in th...

Страница 87: ...ssure at the site of installation is 32 3 ft wg From the steel pipe data table Section 3 the cross sectional area of the 1 1 4 pipe is 965 mm2 0 0104 ft2 Therefore the water velocity at the inlet pipe 2 674 0 0104 257 12 ft min 4 28 ft sec At 12 C 53 6 F the vapour pressure of water is 0 48 ft wg Entering equation 2 NPSHA 32 2 2 3 4 282 2 32 17 0 48 33 7 ft From the pump curve we find that NPSHR 0...

Страница 88: ...ntenance service This can also occur when there are air leaks along the suction pipe causing air entrainment In open systems vortexing of the water can also cause air to be drawn into the pump See Appendix 10 When this happens we need to release the air from the pump This can be done by opening the air bleed hole on the pump housing While the pump is running slowly open this hole and allow the air...

Страница 89: ...unit continues to operate What is the effect of having the compressor switching ON OFF too frequently The main problem is overheating of the compressor motor winding The winding will not get sufficient cooling from the refrigerant flow and also there may be insufficient oil return which causes insufficient lubrication Therefore it is vital that a proper calculation of the total system water volume...

Страница 90: ...an 8 cycles per hour The above recommendations are applicable for close piping systems In the case of open systems whereby there is an external tank there should be no problem of having the compressor short cycling as the additional volume of water in the external tank will take a much longer time to pull down the temperature With the series C chillers no buffer tank is required This is because of...

Страница 91: ...res m Steel Schedule 40 ST NPS 1 2 0 196 3 4 0 344 1 0 558 1 1 4 0 965 1 1 2 1 313 2 2 165 2 1 2 3 089 Copper Type L OD 1 2 0 094 5 8 0 151 3 4 0 225 7 8 0 312 1 1 8 0 532 1 3 8 0 811 1 5 8 1 148 2 1 8 1 997 2 5 8 3 079 PVC DIN 8062 OD 20mm 0 227 20 25mm 0 353 25 32mm 0 581 32 40mm 0 908 40 50mm 1 425 50 The volume is then calculated by multiplying the above figures with the corresponding length u...

Страница 92: ...omponents in the unit and also may cause cracking of the piping network This is due to the expansion of the hot water in the pipes To allow for this expansion or contraction the tank provides an interface point between the water and a compressible gas e g air or nitrogen There are 3 types of expansion tank available a A closed tank which contains a captured volume of air and water b An open tank i...

Страница 93: ...higher temperature α is the linear coefficient of thermal expansion for the b 11 7 10 6 m m K for steel 17 1 10 6 m m K for copper At is higher temperature t2 lowe P1 is the pressure at lower temperature P2 is the pressure at higher temperature To size rature t1 as the design chilled water temperature e g 7 C and the higher temperature t2 as design hot water temperature e g 40 C Using Water volume...

Страница 94: ...r at the highest point of a vertical pipe system To calculate the expansion tank size for cooling only systems use the lower temperature as the design chilled water temperature and the higher temperature as the ambient temperature e g 35 C Generally the size of the expansion tank for chilled water system is much smaller compared with the hot water applications Using a larger expansion tank than th...

Страница 95: ...k to the water pipe make a tee joint at the point of installation Most tanks have threaded ends for connection purposes Tank There is an option to also install a ball valve here for servicing threaded end e g φ 3 4 purposes pump suction line tee joint Section 6 Page 93 ...

Страница 96: ...opper pipes It is important that the thickness of the insulation material used for the pipes are sufficient to fulfill the above mentioned requirements Hence it is recommended that a calculation check to be made to determine the insulation performance To do this the following items must be known 1 Insulation material thermal conductivity coefficient k 2 Pipe Size 3 Air condition dry bulb temperatu...

Страница 97: ...nt air temperature A is the surface area By equating the conductive and convective heat transfer equations it can be shown r1 ln r2 r1 k T1 T2 h T2 Ta Therefore with the known k value and h value together with the pipe size r1 and operating temperature T1 we can calculate the external radius r2 to obtain a specified external surface temperature T2 a We can thus calculate the minimum required insul...

Страница 98: ...the cladding is a good thermal conductor it is possible to ignore this thin metal usually 0 3 0 5 mm thick in the calculation of the polyurethane thickness required Nevertheless if necessary the following equation can be used r3 kb ln r1 r2 ka ln r1 r2 ka kb T3 T1 h T3 Ta where ka and kb are the k values for the two different material r3 and T3 are the radius and surface temperature of the externa...

Страница 99: ...l cladding gives a good finishing to the installation Paint can be applied easily over the metal providing protection against corrosion and giving colour codes to the different pipes used Disadvantages a High cost b Joints with fittings and between pipes require additional insulation moulding This is done by making a mould with thin metal sheets aluminium or GI around the fitting or pipe joint A m...

Страница 100: ...on Tubular form of this insulation are usually used for the copper pipes However sheet form are also used to insulate storage tanks ductwork and steel pipes This insulation is soft flexible and easy to install It can be formed to suit various shapes and sizes For the tubular form the insulation can either be slipped on or snapped on Adhesive is then used to stick together all the joining surfaces ...

Страница 101: ...g Excel spreadsheet programme we calculate 1 For a 7 C water temperature the insulation must be at least 1 inch thick 2 For a 2 C water temperature the thickness required is 1 1 inch It is recommended that the next size up to be selected to provide some safety factor for the selection If a pre insulated pipe is used instead what is the thickness required Ignoring the effect of the external claddin...

Страница 102: ... 2 Pipe surface temperature ºC Insulation material Material Pre insulated polyurethane pipe Thermal conductivity k 0 025W mK Surface convective heat transfer 9 W m2 K Coefficient h Insulation selection Calculated insulation size r2 37 004mm Insulation thickness 21 1mm Minimum 0 8in USE THE NEXT SIZE THICKNESS AVAILABLE OR THICKER FOR SAFETY FACTOR Section 7 Page 100 ...

Страница 103: ... 7 Pipe surface temperature ºC Insulation material Material Pre insulated polyurethane pipe Thermal conductivity k 0 025W mK Surface convective heat transfer 9 W m2 K Coefficient h Insulation selection Calculated insulation size r2 37 004mm Insulation thickness 18 5 mm Minimum 0 7in USE THE NEXT SIZE THICKNESS AVAILABLE OR THICKER FOR SAFETY FACTOR Section 7 Page 101 ...

Страница 104: ... 15 879 mm 7 Pipe surface temperature ºC Insulation material Material ARMAFLEX Thermal conductivity k 0 0374W mK Surface convective heat transfer 9 W m2 K Coefficient h Insulation selection Calculated insulation size r2 41 440mm Insulation thickness 25 6 mm Minimum 1 0 in USE THE NEXT SIZE THICKNESS AVAILABLE OR THICKER FOR SAFETY FACTOR Section 7 Page 102 ...

Страница 105: ...r1 15 879 mm 2 Pipe surface temperature ºC Insulation material Material ARMAFLEX Thermal conductivity k 0 0374W mK Surface convective heat transfer 9 W m2 K Coefficient h Insulation selection Calculated insulation size r2 44 980mm Insulation thickness 29 1 mm Minimum 1 1 in USE THE NEXT SIZE THICKNESS AVAILABLE OR THICKER FOR SAFETY FACTOR Section 7 Page 103 ...

Страница 106: ...ladding The k value of the insulation material is 0 035 W m K The air temperature around the pipes is 34 C By entering the data into the Excel spreadsheet programme we can determine that the insulation thickness required is at least 0 5 inch It should be noted that the closer the external surface temperature is to the ambient air temperature the thicker will the insulation be It is not possible to...

Страница 107: ...temperature ºC Insulation surface temp ºC 37 OK Insulation material Material Fiberglass Thermal conductivity k 0 0374W mK Surface convective heat transfer 9 W m2 K Coefficient h Insulation selection Calculated insulation size r2 24 956mm Insulation thickness 12 3 mm Minimum 0 5 in USE THE NEXT SIZE THICKNESS AVAILABLE OR THICKER FOR SAFETY FACTOR Section 7 Page 105 ...

Страница 108: ...emperature applications Some also have graphical methods for this purpose Computer selection programmes are also available See Appendix 14 for an example of a nomograph used by Armaflex Whatever method is used it is a good practice to use a thicker insulation size to cater for any unforseen circumstances However this must be balanced with economic consideration as thicker material will cost more S...

Страница 109: ...rmal expansion and contraction of the pipe bends and loops Generally the pipes from the mini chiller unit are run along the ceiling space along wall surfaces through floor slabs through walls and also along the floor level The following diagrams give suggestions on how various pipe supports are used for the different type of applications Other than that the number of supports must be sufficient al...

Страница 110: ...mesh size used in the strainer itself A filter mesh size of 16 20 is recommended for this purpose Nevertheless it is also a good practice to install another water filter along the make up water supply pipe for the same purpose It is important that these filter elements to be serviced periodically to remove any trapped particles and debris inside them Flushing of the pipes periodically with water i...

Страница 111: ... This is due to the sudden block of water flow by the debris 2 Both the organic and inorganic surface fouling will show a gradual increase of pressure drop and a gradual drop in the heat exchanger performance Remedy For both the above symptoms it is necessary to remove all these fouling material in order to have an optimum chiller performance We have mentioned earlier that the coarse debris is rel...

Страница 112: ...tion with other chemicals to enhance the cleaning capabilities Whatever type of acids used care must be taken in handling the chemical A concentration 2 to 5 should be mixed and circulated into the system An additional inhibitor chemical may be added if necessary to diminish the corrosive action onto metals Refer to the chemical manufacturer recommendations on the required dosage to use Upon compl...

Страница 113: ...r to cleaning instructions provided by the manufacturers BRAZED PLATE Water inlet HEAT EXCHANGER R 22 outlet Water outlet R 22 inlet anti freeze sensor position 1 2 female socket entering water sensor position 1 2 female socket Drain away the cleaning chemical If necessary a neutralizing agent e g sodium hydroxide can then be pumped in a similar manner Refer to the chemical manufacturer s instruct...

Страница 114: ...erve for excessive impurities and rust For open systems this can be done from the reservoir tank If the water is dirty e g dark brown in colour drain away the water and refill with clean water It is recommended that the water to be replaced at least once a year to prevent fouling on the BPHE If the water quality is poor this should be done more regularly Close monitoring will be required Section 9...

Страница 115: ...nti freeze glycol solution There are two commonly used types ethylene glycol and propylene glycol In some instances brine sodium chloride is used Whatever type is used the quantity mixed with the water must be sufficient to reduce the water freezing point to cater for the operating water temperature in the process cooling It is recommended the freezing point is at least 3 C below the operating tem...

Страница 116: ...en when designing and selecting the chiller unit for such a system Failure to do so may result in insufficient capacity and water flow rate Guidelines 1 Before applying the glycol solutions thoroughly clean and flush the system Reaction with sludge rust deposits and oil may retard the inhibitor function This is especially so after using cleaning agents in the BPHE Complete removal of the cleaning ...

Страница 117: ...to 15 C Because of the higher water temperature several precautions must be taken into consideration when using this system Application considerations 1 In multiple chiller installation all the chillers must either run in the cooling mode or heating mode We cannot have a few units running cooling cycle while the rest running heating cycle because this may damage the compressor as a result of overl...

Страница 118: ... higher water temperature This is because the vapour pressure of water will increase and will reduce the NPSHA Refer to Section 5 Therefore the risk of cavitation occuring in the pump is higher with hot water systems Adjustments to the system may be necessary for a safe operation 9 The hot water will cause expansion of the pipes The linear thermal expansion for carbon steel and copper changes as f...

Страница 119: ...for remedial actions It may be necessary to consult trained service personnel to perform some minor adjustments to optimise this defrost cycle 11 It is an option whether to install or not a safety pressure relief valve into the pipe system It is recommended for safety purposes but this will increase the cost of installation Such valves are useful to protect against overheating of water when the ot...

Страница 120: ...mperature gets too hot Generally heaters are easy and convenient to use However the operating cost of the electricity used is high 2 Hot water boiler diesel fired fuel oil fired or gas fired Boilers can handle larger heating loads with a lower operating cost when compared with heaters With proper installation and maintenance boilers can be made to run with high efficiencies Nevertheless the operat...

Страница 121: ...anger in the fan coil unit Therefore both the chilled water and hot water flow can be regulated and controlled inde It is city of t f the boil When the 3 way positioning valve is at A AB chilled water will flow into the loads When the 3 way positioning valve is at B AB hot water will flow into the loads Since the pump is in the mini chiller unit an additional pump is required to circulate the hot ...

Страница 122: ...expansion tank is also required for the hot water system By is configuration we can have the cooling coil in the fan coil unit for humidity ontrol of the air and the heating coil to reheat the air Nevertheless this method more expansive as the pipe network is more extensive th c is Section 10 Page 120 ...

Страница 123: ... of the PCB and internal wiring of the chiller To connect the power supply cord open the knockout hole on the chiller unit near the control box Insert the power cord into the hole and connect them to the terminal blocks provided in the control box R S T N and Earth The following recommended power cable wire sizes are reproduced here from the IOM AC40A AC50A AC58A AC75B AC100B AC125B AC40AR AC50AR ...

Страница 124: ... the bottom of the trunking to drain out any water drain holes 4 Do not run the wires beneath the chiller unit Condensate from the heat exchanger or during the defrost cycle may drip down onto the wires 5 Do not run the wires through a location which may accumulate water especially after rain 6 It is vital that the chiller unit has proper Earthing Make sure that the Earth wire is present and conne...

Страница 125: ...he upper condensing unit The incoming power supply cable and interconnecting cable will enter into this box Terminal blocks are also provided for cable termination The following pages will describe some examples of the wiring configuration between the mini chiller and fan coil units Please note the following items for these examples a The option Alarm LED from terminal AL1 and AL2 is meant to be i...

Страница 126: ...ver as a result the water pump will also follow this ON OFF cycle This is not recommended for low water temperature settings whereby the pump must be ON all the time to prevent water freezing in the BPHE A ins o COMP By so doing the chiller and pump will keep on running as long as the fan coil unit is ON Method 2 OPTION AC DC supply 12VDC or 240VAC Power cord Remote ON OFF Alarm switch LED UPPER R...

Страница 127: ...M FH SH TH L N E Power cord Thermostat RTH 1 phase Fan speed controller 3 way valve 3WV Power cord 3 phase UPPER Remote R S T N E CONDENSING ON OFF UNIT switch 1 2 COMP N E AL1 AL2 12V 12V R S T N BOTTOM COMPARTMENT FCU termination will be as follows ote External installation required for the fan speed controller and room thermostat not provided If the fan coil unit do not a controller board in it...

Страница 128: ...dby mode will automatically run the water pump when the air temperature sensor measures 5 C even though the FCU is OFF This method is not preferred due to stopping of the water pump once the room load has been achieved A better alternative to this is to use the L terminal from the fan coil unit and connect it to 2 instead Method 2 OPTION AC DC supply 12VDC or 240VAC Power Remote cord ON OFF switch...

Страница 129: ... At position 2 the chiller goes into standby mode This changeover switch can be located in the room itself or outside near the chiller unit Note The mode changeover is done by using manual switching FL FM FH SH TH L N E Power cord Thermostat RTH 1 phase Fan speed controller 3 way 3WV Power valve cord 3 phase COND FCU UPPER Remote R S T N E ENSING 1 ON OFF Switch UNIT switch 3 2 the auxillary relay...

Страница 130: ...COOL and 12V terminals are connected together A manual switch or an auxillary relay contact can be used for this purpose Since this larger chillers are usually installed with multiple fan coil units the control signal wire from them to the chillers is more complicated See next page for more details ater ump and For this option a room thermostat is used to initiate the cooling cycle The w p compres...

Страница 131: ... we need to use auxillary relay C1 C2 and C3 which will energise when the corresponding fan coil unit is ON This in turn will then energise auxillary relay C4 which has a contact with the COOL and 12V terminals of the chiller to initiate the cooling mode The FCU thermostat will cycle the compressor ON OFF according to the load demand Page 129 Remote ON OFF Auxillary contact C4 Power cord 1 2 N AL1...

Страница 132: ...WV 3WV L N E C1 C2 C3 FCU 1 FCU 2 FCU 3 C1 C2 C3 C4 This is a variation of the previous example whereby the power supply to the fan coil units are 1 phase The basic circuitry is the same Page 130 Remote ON OFF Auxillary contact C4 Power cord 1 2 N AL1 AL2 C OL FS P OL LP HP HEAT COOL 12V 12V R S T N E Screw terminal ...

Страница 133: ...1 AL2 C OL FS P OL LP HP HEAT COOL 12V 12V R S T N E Screw terminal The wiring configuration for this heat pump version is very similar to the cooling only model The only difference is the manual mode changeover switch between the COOL and HEAT terminals The following example will show how the connection is made with the multiple fan coil units Section 11 Page 131 ...

Страница 134: ... here The auxillary relay contact C4 will energise but a manual selector switch must be turned to select the required operating mode Note that the power supply to the fan coil units is 3 phase When neither the COOL nor HEAT mode is selected the chiller will go into Standby mode Page132 Remote ON OFF Manual changeover switch C4 Power cord 1 2 N AL1 AL2 C OL FS P OL LP HP HEAT COOL 12V 12V R S T N E...

Страница 135: ...5BR together with multiple Fan Coil Units Section 11 Page 133 This example is for the fan coil units without a controller board e g CC BW The power supply to the FCU is 1 phase The basic circuitry is the same as before ...

Страница 136: ...ction is optional The ENSAVE terminal acts as a remote ON OFF terminal to operate the chiller a A remote ON OFF switch can be connected to power ON or OFF the chiller unit b Fan coil units can be linked together with the chiller through this terminal i e when the FCU sends a signal to the ENSAVE the chiller will run Or if no FCU is running the chiller will power OFF However if the ENSAVE terminal ...

Страница 137: ...itch 4WV1 4WV2 HTR ALL IN ALL OUT ENSAVE HP1 LP1 FL HP2 LP2 CP1A CP2A CP1B CP2B R S T N Method 2 Optional Signal from FCU Alarm output VALVE relay 4WV1 4WV2 HTR ALL IN ALL OUT ENSAVE HP1 LP1 FL HP2 LP2 CP1A CP2A CP1B CP2B R S T N Power supply Power supply Section 11 Page 135 ...

Страница 138: ...the µCompact named because of the small size It is slotted in front of the control box panel and all connecting wires are done at the back via two terminal blocks GO B1 B2 B3 ID5 ID3 ID1 G GND GND Y GND ID4 ID2 NO1 C 1 2 C 1 2 C 3 4 X C5 NO2 NO3 NO4 C 3 4 X NO5 Other than that there is also a power input terminal block R S T N to connect the main incoming power supply 415V 3 phase 50 Hz All necess...

Страница 139: ...el Controller Field Wiring NEUTRAL R S T REMOTE ON OFF Alarm N output Power device supply GO B1 B2 B3 ID5 ID3 ID1 NO1 C1 2 C1 2 C3 4 X C5 G GND GND Y GND ID4 ID2 NO2 NO3 NO4 C3 4 X NO5 Section 11 Page 137 ...

Страница 140: ...ernal board can communicate with the chiller PCB controller The following are some examples of such modifications Method 1 External of chiller contactor CX CX CX COMP OF PUMP aux aux aux PCB EXTERNAL SWITCHBOARD C W STARTERS R R R In this method the power supply to the contactor of the compressor COMP fan motor OF and pump PUMP is removed and replaced with the supply from the external switchboard ...

Страница 141: ...r the overload protection is now dependent on the overload settings in the external board All the other safety protection devices will still be in operation Method 3 For the third method the entire control box is not used at all Rather the entire power switching and protection is taken up by the external board Power cables from the external board will be connected to the terminal blocks of the con...

Страница 142: ...nternational regulations for guidance The installed system must be properly commissioned to ensure that the original chiller protection system is still in a good working condition Maintenance switch A manual switch is provided inside the chiller control box to allow switching OFF of the system during maintenance servicing of the chiller Do not mistaken this switch as the REMOTE switch described in...

Страница 143: ...owing location Water out Water in BPHE Flow switch The flow switch used in the chiller is JOHNSON CONTROLS model F61KB or F61SB However for field replacements other brands of equivalent sizes may be used The flow switch is of the paddle type whereby the switch is connected mechanically to a length of stainless steel paddles which the water flow will impact upon As a result the paddle will move in ...

Страница 144: ...nternal surface of the pipe and becomes stuck inside As a general rule of thumb the length of the paddle should be at least 5 mm above the bottom of the pipe surface PIPE At least 5 mm paddles distance The flow switch is also mounted vertically with the paddles in a downward position It is screwed into the connecting piping 1 1 4 via a tee adaptor screw thread apply PTFE white tape Flow Tee Sectio...

Страница 145: ...ignal will prompt the controller to give an error code FS on the LED display Some of the typical problems encountered when the FS error code occurred are a the paddle has broken cracked twisted b the paddle has stuck in the pipe c the switch mechanism has jammed e g due to debris d wrong wiring of the NO and NC terminals reversed e failure of the switch contacts e g due to shorting f wrong adjustm...

Страница 146: ...ecked for wrong settings which could cause the system to trip Weather proofing Since the flow switch is exposed to the external elements and also because of the wet operating environment it is vital that the flow switch cover is screwed on tightly and properly For the F61SB model the cover comes with a piece of rubber gasket around the edges to prevent moisture from entering the switch Do not remo...

Страница 147: ...ter proofing The flow switch has three wires coming out of it i e common black normally open blue and normally closed brown The wiring in the chilller has been configured whereby the common and normally open wires are connected to the PCB This means that when there is sufficient water flow the switch contact will close to give a 240 VAC signal to the PCB The operating pressure differential to clos...

Страница 148: ...ow rates through these equipment References to the Technical Manual must be made available Water pressure drop characteristics of these equipment must also be known Once we have all these information we will next need to do some measurements Without any measurement data we cannot do balancing The following are some examples of such measurements 1 Multiple chillers in parallel Pressure gauges C1 Su...

Страница 149: ...balancing valve will have an inlet and an outlet port to allow connection to a pressure meter By measuring this pressure drop across the valve itself the flowrate can be determined by using the valve calibration charts See Appendix 18 for an example Compare these data with the design specifications Adjust the balancing valves where necessary to obtain the required flowrate Note 1 It is also possib...

Страница 150: ...lancing can be counter checked by measuring the water temperature difference between the entering and leaving A result of 4 5 C is expected 3 Temperature measurement In the absence of all the flowmeters pressure gauges and balancing valves the only possible way to do a simple balancing is by measuring the water temperature difference between the entering and leaving A reading of 4 5 C is then used...

Страница 151: ...l force ON the chiller unit to go into HEATING mode Therefore the power supply to the chiller unit must not switch OFF b If it is not possible to have the power supply continuously ON to the chiller then it is recommended to drain all the water in the system An alternative is to pump in glycol solution into the system The concentration must be sufficient to cater for the lowest ambient temperature...

Страница 152: ...n indication of liquid compression which will damage the compressor If such sounds are heard switch off the compressor immediately Allow the crankcase heater to continue warming up the compressor Repeat the restart again If the problem still persists call for service technicians to rectify Section 14 Page 150 ...

Страница 153: ...Appendix 1 ...

Страница 154: ...Appendix 2 Appendix 2 ...

Страница 155: ... 017 092 7 7 5 470 180 10 161 017 093 8 6 6 880 225 10 161 017 094 10 8 10 800 Pipe serie S 6 25 nominal pressure PN16 d PN Code t Kg m 12 16 161 017 104 1 0 0 055 16 16 161 017 105 1 2 0 090 20 16 161 017 106 1 5 0 137 25 16 161 017 107 1 9 0 212 32 16 161 017 108 2 4 0 342 40 16 161 017 109 3 0 0 525 50 16 161 017 110 3 7 0 809 63 16 161 017 111 4 7 1 290 75 16 161 017 112 5 6 1 820 90 16 161 01...

Страница 156: ...EXPANDING SPECIFICATION CU PIPE Ф DIMENSION A mm MM INCH MACHINE MANUAL 6 35 1 4 8 6 7 63 5 16 8 7 9 52 3 8 10 7 12 70 1 2 10 10 15 87 5 8 15 13 19 05 20 17 22 23 7 8 20 15 25 40 1 20 15 28 60 11 8 20 15 Appendix 4 ...

Страница 157: ...GRAPH OF PRESSURE DROP VS FLOW FOR VARIOUS C V RATINGS Appendix 5 1 ...

Страница 158: ......

Страница 159: ...Water Capacity Graph Appendix 5 2 ...

Страница 160: ...CHART 3 FRICTION LOSS FOR CLOSED PIPING SYSTEMS Appendix 6 1 ...

Страница 161: ...CHART 4 FRICTION LOSS FOR OPEN PIPING SYSTEMS Appendix 6 2 ...

Страница 162: ...CHART 5 FRICTION LOSS FOR CLOSED AND OPEN PIPING SYSTEMS Appendix 6 3 ...

Страница 163: ...Hazen Wiilioms Flow Diagram for SSS PIPE up 0 300 mm Diameter U PVC TECHNICAL INFORMATION F54 Head Loss in meters 1000 meters of pipe line Appendix 6 4 ...

Страница 164: ...alve For Y pattern globe lift check valve with seat approximately equal to the nominal pipe diameter use values of 60º Y valve for loss Regular and short pattern plug cock valves when fully open have same loss as gate valve For valve losses of short pattern plug cocks above 6 ins check manufacturer For 045 thru 3 16 in perforations with screens 50 clogged loss is doubled Appendix 7 1 ...

Страница 165: ...0 7 5 3 1 2 9 0 5 9 15 4 7 7 3 15 18 5 9 8 0 9 0 4 10 6 7 17 5 2 8 5 17 21 6 7 9 0 10 5 13 8 2 21 6 5 11 21 25 8 2 12 13 6 16 10 25 7 9 13 25 30 10 14 16 8 20 13 10 33 40 13 18 20 10 25 16 13 42 50 16 23 25 12 30 19 16 50 60 19 26 30 14 34 23 18 55 68 23 30 34 16 38 26 20 62 78 26 35 38 18 42 29 23 70 85 29 40 42 20 50 33 26 81 100 33 44 50 24 60 40 30 94 115 40 50 60 MITRE ELBOWS 90º EII 60º EII ...

Страница 166: ... 1 2 2 9 2 2 1 2 6 6 3 3 6 6 5 0 2 8 0 4 8 1 6 4 0 3 0 1 6 9 0 4 4 9 0 6 8 10 6 1 2 0 5 0 3 8 2 0 12 5 6 12 8 7 3 13 8 0 2 6 6 5 4 9 2 6 14 7 2 14 11 15 9 2 3 0 7 7 6 0 3 0 17 8 5 17 13 4 17 11 3 8 9 0 6 8 3 8 20 10 20 16 5 24 15 5 0 12 9 0 5 0 27 14 27 20 6 29 22 6 0 15 11 6 0 33 19 33 25 8 25 8 5 15 8 5 47 24 47 35 10 32 11 20 11 60 29 60 46 12 41 13 25 13 73 37 73 57 14 16 16 86 45 86 66 16 18 ...

Страница 167: ...0 5 Elbow welded 90 0 5 0 5 Reduced coupling 0 4 0 4 Open return bend 1 0 1 0 Angle radiator valve 2 0 3 0 Radiator or convector 3 0 4 0 Boiler or heater 3 0 4 0 Open gate valve 0 5 0 7 Open globe valve 12 0 17 0 Source Giesecke 1926 and Giesecke and Badgett 1931 1932a a See Table 6 for equivalent length of one elbow Notes 1 Chart is based on straight tees e branches A B and C are the same size 2 ...

Страница 168: ...Appendix 8 Appendix 8 ...

Страница 169: ...Appendix 8 1 ...

Страница 170: ...Appendix 8 2 ...

Страница 171: ...Appendix 8 3 ...

Страница 172: ...Appendix 8 4 ...

Страница 173: ...Appendix 8 5 Appendix 8 5 ...

Страница 174: ...Appendix 8 6 Appendix 8 6 ...

Страница 175: ...Appendix 8 7 Appendix 8 7 ...

Страница 176: ...Appendix 9 ...

Страница 177: ... bottom connection in an open tank 7 c Vortex plate for side exit from tank 8 d Slotted pipe in vortex breaker 9 a Suction elbow in open tank Figure 6 8 Vortexing in HVAC pumps From James H Ingram Suction side problems Gas entrainment Pump and System Magazine September 1994 p 34 Appendix 10 ...

Страница 178: ...Appendix 11 1 Appendix 11 1 ...

Страница 179: ...Appendix 11 2 Appendix 11 2 ...

Страница 180: ...Appendix 13 ...

Страница 181: ...Appendix 13 1 ...

Страница 182: ...Appendix 14 Appendix 14 ...

Страница 183: ...Appendix 15 1 Appendix 15 1 ...

Страница 184: ...Fig 13 Density of Aqueous Solutions of Industrially Inhabited Propylene Glycol vol Fig 10 Specific Heat of Aqueous Solutions of Industrially Inhibited Ethylene Glycol vol Fig 14 Specific Heat of Aqueous Solutions of Industrially Inhibited Ethylene Glycol vol Fig 11 Thermal Conductivity of Aqueous Solutions of Industrially Inhibited Ethylene Glycol vol Appendix 15 2 ...

Страница 185: ...Fig 29 Example of Effect of Aqueous Ethylene Glycol Solutions on Heat Exchanger Output Fig 31 Pressure Drop Correction for Glycol Solutions Fig 30 Effect of Viscosity on Pump Characteristics Appendix 16 ...

Страница 186: ...Appendix 17 Appendix 17 ...

Страница 187: ...Appendix 18 ...

Страница 188: ...CE20DW CE25DW Note PRESSURE DROP CORRECTION FACTOR 1 2947 0 0021 EWTºF Appendix 19 ...

Страница 189: ... 2003 McQuay International 603 55194922 www mcquayup com ISO 9002 REGISTERED ...

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