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Bosch FHP RT-20, Installation, Operation And Maintenance Manual, Page: 13 / 52

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Bosch FHP RT-20 Installation, Operation And Maintenance Manual Download Page 13

13

Model RT Energy Recovery Unit

Curb Outside Dimensions and Weights

Roof Curb Mounting

Rooftop units require curbs to be mounted first. The 
duct connections must be located so they will be 
clear of structural members of the building.

1  Factory Supplied Roof Curbs: 

Roof curbs are 

Model GKD, which are shipped in a knockdown kit 
(includes duct adapter) and require field assembly (by 
others). Assembly instructions are included with the 
curb.

2  Install Curb: 

Locate curb over roof opening 

and fasten in place. (Refer to Recommended Roof 
Openings). Check that the diagonal dimensions 
are within ±1/8 inch of each other and adjust 
as necessary. For proper coil drainage and unit 
operation, it is important that the installation be level. 
Shim as required to level.

3  Install Ductwork: 

Installation of all ducts should 

be done in accordance with SMACNA and AMCA 
guidelines. Duct adapter provided to support ducts 
prior to setting the unit.

4  Set the Unit: 

Lift unit to a point directly above the 

curb and duct openings. Guide unit while lowering to 
align with duct openings. Roof curbs fit inside the unit 
base. Make sure the unit is properly seated on the 
curb and is level.

Curb Outside Dimensions

Curb Cap Dimensions

Unit Size

A

B

C

D

E

RT-20

2.00

2.00

1.00

0.88

0.75

RT-45

2.00

4.25

2.00

1.31

0.50

RT-55

2.00

4.25

2.00

1.31

0.50

RT-90

2.00

4.25

2.00

1.31

0.50

All dimensions are in inches. 

Rail Mounting

Unit Size

A

B

RT-20

5.0

41.0

RT-45

7.0

41.9

RT-55

5.5

53.0

RT-90

6.0

59.0

All dimensions are in inches. 

Curb Outside Dimensions and Curb Weights (lbs)

Unit Size

L

W

Weight

RT-20

104.88

51.00

310

RT-45

115.75

60.63

400

RT-55

129.88

71.50

510

RT-90

148.13

90.75

720

All dimensions are in inches. Weights are for 12 inch 

high curbs. Roof curb details, including duct locations 

dimensions are available on RT roof curb assembly 

instructions, part #468280

ROOF CURB

SIDE OF UNIT

BASE

1 INCH INSULATION

E

D

C

A

B

Curb Cap Details for Factory Supplied Roof Curbs

Rail Mounting / Layout

  •  Rails designed to handle the weight of the RT 

should be positioned as shown on the diagram 
(rails by others).

  •  Make sure that rail positioning does not interfere 

with the supply air discharge opening or the 
exhaust air intake opening on the RT unit. Avoid 
area dimensioned “B” below.

  •  Rails should run the width 

of the unit and extend 
beyond the unit a 
minimum of 12 inches 
on each side.

  •  Set unit on rails.

B

A

Supply/Exhaust

Outdoor Air Intake Hood

Opening

Isometric view 
of unit on rails

B

A

Supply/Exhaust

Outdoor Air Intake Hood

Opening

Side view of unit on rails

Summary of Contents for FHP RT-20

Page 1: ...da 2 All moving parts must be free to rotate without striking or rubbing any stationary objects 3 Unit must be securely and adequately grounded 4 Do not spin fan wheel faster than maximum cataloged fan RPM Adjustments to fan speed significantly effects motor load If the fan RPM is changed the motor current should be checked to make sure it is not exceeding the motor nameplate amps 5 Do not allow t...

Page 2: ...ny items are missing report shortages to your local representative to arrange for obtaining missing parts Sometimes it is not possible that all items for the unit be shipped together due to availability of transportation and truck space Confirmation of shipment s must be limited to only items on the bill of lading See also Installation Lifting Handling Units are to be rigged and moved by the lifti...

Page 3: ...Connection 17 Control Center Components 18 Optional Preheater 19 Optional Post Heater 19 Post Heater Control Panel 19 Electric Heater Application Operation 19 Optional Service Outlet 19 Optional Vapor Tight Lights 19 Typical Wiring Diagram 20 Microprocessor Controller Sequence of Operation 21 22 Energy Wheel Sequence of Operation 23 Electrical Controls Frost Control Application Operation 24 Timed ...

Page 4: ...n fresh outdoor air and removes stale exhaust air from the building The intake and exhaust airstreams move through the RT in opposite directions in separate passages and each airstream passes through an energy wheel In cooling mode the energy wheel removes both heat and moisture from the incoming airstream and rejects it into the exhaust airstream In heating mode the energy wheel removes heat and ...

Page 5: ...and then delivering the dehumidified air at a neutral temperature to the space A hot water coil is available as an option and is used for supplementary heat for the building If present this coil will be installed in the supply airstream mounted vertically on the interior wall that separates the supply air blower and motor from the airside coil compartment Owner s Information Motorized Recirculatin...

Page 6: ...al Refrigerant Flow Schematic in this IOM In normal use the heat pump module requires only periodic inspection and cleaning Any servicing or repairs must be performed by an EPA Certified Technician Unit Protection Module UPM Refrigerant Reversing Valves Water Intake and Discharge Connections Coaxial Refrigerant to Water Heat Exchangers High Efficiency Scroll Type Compressors RT Heat Pump Module Wh...

Page 7: ...g with access to burners vest plate and circuitry Optional Electric Heater Location Model PVF Indirect Gas Furnace Optional Electric Preheater Location Supply Air Motor and Blower Assembly RT Optional Indirect Gas Furnace An optional Indirect Gas furnace may be installed in the RT and its function is to provide supplementary emergency heat to the building The Model PVF Indirect Gas Furnace is inst...

Page 8: ...duction in airflow can cause the airside coils to get too cold As this happens ice buildup on the face of the coil is possible further reducing airflow The result of the airside coil operating at temperatures below design limits is that excessive liquid refrigerant will be returned to the compressor s The liquid refrigerant buildup in the compressor s will displace the necessary oil needed for pro...

Page 9: ...t air and return air ducts may be accomplished either by cutting individual duct openings or by opening the entire space within the roof curb unit If the entire space within the curb is opened higher radiated sound levels may result Whenever supply or warm air ducts pass through a combustible roof clearance of at least one inch 25 mm must be maintained between the outside surfaces of the ductwork ...

Page 10: ...al Frost control sensors optional Economizer sensors optional Electric preheater optional 7 Airside coil access Drain pan 8 Outdoor air blower motor if equipped with optional IG furnace 9 Outdoor air blower motor electric post heater if equipped with optional electric post heater Model RT with Heat Pump Model Overall Exterior Dimensions Width including Lifting Lugs Overall Width with Exhaust Hood ...

Page 11: ...20 RT 45 RT 55 RT 90 Clearances for service and component removal on RT 20 and RT 45 Clearance for energy wheel removal on RT 20 Clearance for energy wheel removal on RT 45 Clearances for service and component removal on RT 55 and RT 90 WHEEL CASSETTE COIL SECTION ACCESS PANEL ACCESS PANEL ACCESS PANEL ACCESS PANEL ACCESS PANEL ACCESS PANEL ACCESS PANEL EXHAUST HOOD OUTDOOR AIR HOOD INTAKE EXHAUST...

Page 12: ...ns section for more details Lifting 1 Before lifting be sure that all shipping material has been removed from unit 2 To assist in determining rigging requirements weights are shown below 3 Unit must be lifted by all lifting lugs provided on base structure 4 Rigger to use suitable mating hardware to attach to unit lifting lugs 5 Spreader bar s must span the unit to prevent damage to the cabinet by ...

Page 13: ...Outside Dimensions Curb Cap Dimensions Unit Size A B C D E RT 20 2 00 2 00 1 00 0 88 0 75 RT 45 2 00 4 25 2 00 1 31 0 50 RT 55 2 00 4 25 2 00 1 31 0 50 RT 90 2 00 4 25 2 00 1 31 0 50 All dimensions are in inches Rail Mounting Unit Size A B RT 20 5 0 41 0 RT 45 7 0 41 9 RT 55 5 5 53 0 RT 90 6 0 59 0 All dimensions are in inches Curb Outside Dimensions and Curb Weights lbs Unit Size L W Weight RT 20...

Page 14: ...el Dia 1 Fan Wheel Dia Rot a t i o n Rot a t i o n R o tation R o tation Length of Straight Duct GOOD POOR GOOD POOR GOOD POOR Turning Vanes Turning Vanes SYSTEM EFFECT FACTOR CURVES FPM X 100 OUTLET VELOCITY 0 5 10 15 20 25 30 35 40 45 1 2 1 0 0 8 0 6 0 4 0 2 0 0 STATIC PRESSURE LOSS CURVE 1 CURVE 2 CURVE 3 CURVE 4 Recommended Discharge Duct Size and Length Model Blower Size Duct Size Straight Du...

Page 15: ... P trap If local and area building codes permit the condensate may be drained from the P trap onto the roof but a drip pad should be provided beneath the outlet If local and area codes require a permanent drain line it should be fabricated and installed in accordance with Best Practices and all codes In some climates it will be necessary to provide freeze protection for the P trap and drain line T...

Page 16: ...ure to replace grommets will result in water leakage into the unit and altered performance 3 The air vent at the uppermost point should be temporarily opened during system start up to release all of the air from the coil To maintain heat transfer capacity periodically vent any air in coil Hot water coil connections Coil access door 4 Water coils are not normally recommended for use with entering a...

Page 17: ... the unit preferably in the area of the Control Center Carefully select a location that does not interfere with other controls or assemblies such as the motorized dampers Seal penetration in cabinet bottom to prevent leakage The electric supply to the unit must meet stringent requirements for the system to operate properly Voltage supply and voltage imbalance between phases should be within the fo...

Page 18: ...l 5 24 Vac Control Transformer 6 24 Vac Terminal strip 7 Fuses for blower motors 8 Grounding lug 9 Distributor block 10 Compressor fuse blocks 11 Compressor contactors 12 Condensing fan contactors 13 Compressor cycle timers 14 Compressor relay 15 Terminal block Optional Control Center Components 16 DDC controller 17 Dirty filter pressure switches 18 Economizer module 19 Thermostats for Economizer ...

Page 19: ...turn on If the first stage does not satisfy the set point the second stage will also turn on See also Subassemblies Electric Heaters Post heaters Post heaters are standard as SCR control see unit specific wiring diagram A temperature sensor with field adjustable set point is mounted in the outdoor airstream after the post heater to turn the post heater on A SCR heater provides an infinitely modula...

Page 20: ...ing and field wiring are also indicated This particular example includes 1 variable frequency drives on the blowers requiring a modulating input 2 modulating energy recovery wheel with factory controls for economizer 3 energy wheel rotation sensor 4 outdoor air and exhaust air dirty filter switches 5 motorized outdoor air and exhaust air intake dampers and 6 timed exhaust frost control Many other ...

Page 21: ...d mode when there is a recirculation damper and a room temperature sensor wired to unit 1 Exhaust fan off 2 Supply fan off 3 Recirculation air damper open 4 OA Damper Closed 5 On a call for heating room temp set point differential 65 F 5 F 60 F supply fan cycles on and the heating increases the room temperature Unit cycles off when room temperature reaches the unoccupied set point 65 F adjustable ...

Page 22: ...g set point of 70 F Supply Set Point Reset Function Either a room temperature sensor or the outdoor air reset function if no room temperature sensor wired to controller will determine the supply temperature of the unit Outdoor Air Reset Function With no room temperature sensor available the controller will default to discharge temperature control based on outdoor air temperature The controller wil...

Page 23: ...n that signals the DDC to activate an alarm Supply and Exhaust Air Alarm DDC monitors proving switch on each blower and displays an alarm in case of blower failure Dirty Wheel Alarm DDC monitors pressure across the wheel and sends an alarm in the case of an increased pressure drop DX Alarm DDC monitors the refrigerant pressure and shuts off refrigeration circuit in the case of high or low refriger...

Page 24: ... the temperature sensor up as high as possible The supply blower should cycle on for one minute then turn off for one minute After testing set the Timer Scale as follows T1 10 minutes T2 1 hour Set the Timer Settings as follows T1 0 5 T2 0 5 The timer is now set for 5 minutes off and 30 minutes on Remember to remove the jumper Electric preheat frost control includes an electric heater at outdoor a...

Page 25: ... Disconnect C7400 solid state enthalpy sensor from terminal So on the enthalpy controller Also disconnect the 620 ohm resistor from terminal Sr on the enthalpy controller Turn unit power on The LED on the enthalpy controller should light and the energy recovery wheel should not rotate Turn unit power off Reconnect 620 ohm resistor to terminal Sr on the enthalpy controller Turn unit power on The LE...

Page 26: ...y to any connected motor thus changing the speed of rotation The VFD is preset at the factory to respond to conditions specified by the owner In some cases the VFD will be controlled by owner installed sensors and controlling devices such as CO2 sensors dehumidistats or pressure sensors The VFD is sometimes an element of the frost control process for the energy wheel Refer to the VFD manufacturer ...

Page 27: ...e remote panel is a series of junction boxes ganged together and includes a stainless steel faceplate The remote panel is available with a number of different alarm lights and switches to control the unit The remote panel ships loose and requires mounting and wiring in the field The remote panel is available with the following options Unit on off switch Unit on off light 7 day time clock Hand off ...

Page 28: ...if there is power at the alert signal leads refer to electrical diagram Whether there is power or not turn the adjustment screw on the dirty filter gauge clockwise if you did not have power counterclockwise if you did have power until the power comes on or just before the power goes off Open the filter compartment and remove the obstructing material Replace the door and check to make sure that you...

Page 29: ...s Terminal Strip Labels OAF A Supply Fan Amps EF A Exhaust Fan Amps Sensors Mounted by Factory Factory mounted temperature pressure and current sensors are available in the locations indicated on the unit diagram below A list of available sensors is shown below The specific sensors provided on a given unit are labeled in the unit control center on the terminal strip Sensors are wired to the termin...

Page 30: ...sition and the two wires found on the back of the sensor are to be connected to terminals B5 and BC5 on the Microprocessor Controller See also unit specific wiring diagram Microprocessor DDC Remote Interface The optional Remote Interface Panel permits viewing of settings that are present on the microprocessor controller DDC and also permits inputting of new settings It is to be field installed and...

Page 31: ...Overload each compressor is equipped with an auto reset thermal overload High Temp Protection internal devices within the compressor protect it against excessively high discharge gas temperatures only on compressors above 6 hp Crankcase Heater liquid refrigerant is incompressible Therefore a crankcase heater is installed around the base of each compressor in the unit to boil off any liquid refrige...

Page 32: ...ls below 18 VAC The unit will remain off until a minimal incoming power of 18 VAC is detected Once proper power is restored the unit will start up within the random start time period Malfunction Output The controller has a set of wet contacts for remote fault indication or dry contacts for communication with a DDC controller or BMS The fault output will depend on the dip switch setting for ALARM I...

Page 33: ...ltage to R and C terminals below 18 VAC Intelligent Reset If a fault condition is initiated the five minute delay on break time period and the random start timer is initiated and the unit will restart after these delays expire During this period the fault LED will indicate the cause of the fault If the fault condition occurs 2 or 4 times depending on 2 or 4 setting for Lockout dip switch before 60...

Page 34: ...pulley and over the wheel rim Air Seals Check that the air seals located around the outside of the wheel and across the center both sides of wheel are secure and in good condition Air seal clearance is determined by placing a sheet of paper to act as a feeler gauge against the wheel face To access seals enter unit for RT 55 and RT 90 or pull out the cassette for RT 20 and RT 45 following the instr...

Page 35: ... 55 F 145 psig 10 F Superheat Water entering the coaxial heat exchanger is warmed by the heat it absorbs from the refrigerant and leaves about 10 F warmer Location Refrigerant State Temperature Pressure Superheat Subcool Heating Mode Refrigerant Properties Before Airside Coil Hot Vapor 130 F 250 psig 50 F Superheat After Airside Coil Warm Liquid 65 F 250 psig 15 F Subcool After Thermostatic Expans...

Page 36: ...t As part of that process the following checklist must be completed and information recorded Starting up the unit in accordance with this checklist will not only ensure proper operation but will also provide valuable information to personnel performing future maintenance Should an issue arise which requires factory assistance this completed document will allow unit experts to provide quicker resol...

Page 37: ... measuring pipe temperature 1 Restore or install thermostat or controller connections at terminals R and G on the terminal strip 2 Set thermostat to the highest setting 3 Set the thermostat mode switch to cool and the fan switch to the auto position Reversing valve solenoid should energize Compressor should not run 4 Reduce the thermostat setting to approximately five degrees below room temperatur...

Page 38: ...______ RH Superheat ________ Deg F Should be between 8 and 12 F Subcooling ________ Deg F Should be between 12 and 17 F Discharge Pressure ________ PSIG Should be between 300 and 500 PSIG for R 410A Suction Line Pressure ________ PSIG Should be between 100 and 135 PSIG for R 410A Liquid Line Temperature ________ Deg F Suction Line Temperature ________ Deg F Hot Gas Bypass Operational ________ Yes ...

Page 39: ... Yes No EA Dirty Filter Sensor Yes No N A Yes No CO2 Sensor Yes No N A Yes No Service Outlet Yes No N A Yes No Vapor Tight Lights Yes No N A Yes No Remote Control Panel Yes No N A Variable Frequency Drives section Operational Yes No Blower VFDs Yes No N A Yes No Wheel VFD Yes No N A Damper section Operational Yes No Outdoor Air Damper Yes No N A Yes No Exhaust Air Damper Yes No N A Yes No Night Se...

Page 40: ...B report indicates that the airflow on a unit is low prior to contacting the factory please determine the following information Airflow problems can often be tied back to improper ductwork installation Be sure to install ductwork in accordance with SMACNA and AMCA guidelines Unit 1 Unit 2 Unit 3 Unit 4 Model Number Serial Number Nameplate Information Voltage Hertz Phase Outdoor Air Fan Amps Outdoo...

Page 41: ...heck cfm and adjust drives if needed Static pressures are higher or lower than design If higher ductwork should be improved If lower fan rpm should be lower Blower rotation is incorrect Check rotation and reverse if necessary Motor voltage incorrect Check motor nameplate versus supplied voltage Motor horsepower too low See specifications and catalog for fan curves to determine if horsepower is suf...

Page 42: ...rs Wheel out of balance Replace or rebalance Loose wheel on shaft Tighten wheel setscrew Loose motor or blower sheave Tighten sheave setscrew Belts too loose Adjust belt tension after 24 hours of operation Belts too tight Loosen to maintain a 3 8 inch deflection per foot of span between sheaves Worn belt Replace Motor base or blower loose Tighten mounting bolts Buildup of material on wheel Clean w...

Page 43: ...or thermostat to close Loose wiring Check all wire terminals and tighten as necessary Compressor starts but cuts out on low pressure Low pressure switch activates at 50 psig for R 410A Low refrigerant charge Check refrigerant pressures If refrigerant pressure is low check for leaks Airflow restricted Check for dirty evaporator coil dirty filters dampers closed iced evaporator coil improper belt ch...

Page 44: ... discharge pressure Check running amperage and conditions described under Low suction pressure symptoms High suction and discharge pressures Check thermal expansion valve setting check for air in system Defective compressor overload If compressor is hot allow compressor to cool for two hours Recheck for open circuit Improper refrigerant charge Check subcooling Improperly wired Review wiring schema...

Page 45: ...nsion valve not secured to suction line Check the thermal expansion valve ensure bulb is insulated Check superheat If superheat is high then valve is out of control and pegged wide open Check bulb for contact Adjust valve for superheat Replace valve powerhead or valve Thermostatic expansion valve pressure limit feature incorrect or inoperative Overfeeding Check bulb location and clamping Adjust su...

Page 46: ...ressure Insufficient refrigerant charge Check subcooling check for leak Repair leak and add refrigerant Defective or improperly adjusted expansion valve Check superheating and adjust thermal expansion valve Low suction pressure See Low suction pressure Faulty condenser temperature controls Check condenser controls and reset to obtain desired condensing temperature Compressor short cycles Thermosta...

Page 47: ...fective compressor See High suction pressure Restriction in suction and liquid line Check for restrictions in refrigerant circuit Control contacts stuck Check wiring Excessive load Add more equipment or reduce room load Too low of a system thermostat setting or defective thermostat Adjust or replace thermostat Liquid line is too hot Refrigerant undercharge Adjust the charge by subcooling High disc...

Page 48: ...omponents can be heavy and serious injury may occur 3 Motors Check for cleanliness 4 Fan Belts Check for wear tension alignment 5 Blower Wheel Fasteners Check for cleanliness Check all fasteners for tightness Check for fatigue corrosion wear 6 Bearings Lubricate per the schedule in the Fan Bearings section 7 Door Seal Check if intact and pliable 8 Wiring Connections Check all connections for tight...

Page 49: ...n Bearings Most bearings are permanently lubricated and require no further lubrication under normal use Normal use being considered 20ºF to 120ºF and in a relatively clean environment Some bearings are relubricatable and will need to be re greased depending on fan use Check your bearings for grease zerk fittings to find out what type of bearing you have If your fan is not being operated under norm...

Page 50: ...vailable Many coil cleaners contain harsh chemicals so they must be used with caution by qualified personnel only Care must be taken not to damage the coils including the fins while cleaning Caution Fin edges are sharp Drain pans in any air conditioning unit will have some moisture in them therefore algae and other organisms will grow due to airborne spores and bacteria Periodic cleaning is necess...

Page 51: ..._________________________ _________________________________________________ _________________________________________________ Date___________________ Time______________ AM PM Notes ___________________________________________ _________________________________________________ _________________________________________________ _________________________________________________ _________________________...

Page 52: ...service station FHP will not be responsible for any removal or installation costs As a result of our commitment to continuous improvement FHP reserves the right to change specifications without notice AMCA Publication 410 96 Safety Practices for Users and Installers of Industrial and Commercial Fans provides additional safety information This publication can be obtained from AMCA International Inc...

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