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4.4

Head Pressure Is Too High

POSSIBLE CAUSE

Insufficient system airflow

Excessive refrigerant charge
Non-condensables in system
Defective refrigeration valves

Restriction in refrigeration piping

REMEDY

1) Evaluate system airflow

(See Section 5.3.1.1)

2) Check for dirty air filters or

restricted ductwork.

3) Verify that coils are clean.
Re-evaluate system charge.
Evacuate or purge system.
Check 3-way, flooding, solenoid and

check valves for sticking.
1) Check coil and tubing for kinks.

2) Replace dirty drier filter.
1) Reduce entering air temperature or

relative humidity.

2) Check register locations for short

cycling of air.

REMOTE CONDENSER PROBLEMS WHICH CAUSE EXCESSIVE PRESSURES:

Lack of airflow

Remote condenser fan does not run.

Refrigeration system is overloaded

NOTE: LW SERIES DEHUMIDIFIERS

ARE DESIGNED FOR A MAXIMUM

RETURN AIR TEMPERATURE OF 70°F.

Assure remote condenser coil is

clean and no airflow restrictions exist

around unit.

A) Overload is a thermo protector.

Allow to cool to reset. If multiple

trips occur, verify amp draw and

replace motor if necessary.

A) Overload tripped

B) Contactor faulty
C) Blower cycling on internal protection

D) Controller settings

B) Replace contactor.

C) Reduce blower speed.

D) On models with a remote

condenser installed, verify that the

condenser is enabled.

A) Fully open service valves.

B) Re-evaluate remote condenser

installation.

Excessive pressure drop in line sets

NOTE: When the remote condenser is active and the outdoor temperature is
above 95°F, normal head pressure can be as high as 300 psig.

Desert Aire - LW Manual

Содержание LW

Страница 1: ...t temperatures 35 to 80 F Defrost cycle uses hot gas defrost to quickly eliminate frost from evaporator coils Timed defrost cycle initiated automatically only when required Heat of rejection can be delivered to the space or optional remote condenser LW System ...

Страница 2: ...2 ...

Страница 3: ...th each unit and or other documentation provided 2 The Start Up Report must be completed and returned to Desert Aire Service for evaluation If no deficiencies are identified a Warranty Validation Letter will be issued that provides all warranty dates and coverage If installation or start up deficiencies are present these must be corrected and communicated to Desert Aire in order to activate warran...

Страница 4: ...nty Some states do not allow the exclusion of incidental or consequential damages for personal injury so the above limitations may not apply to you for certain damages This warranty gives you specific legal rights and you may also have other rights which vary from state to state No person or representative is authorized to make any warranty or assume any liability not strictly in accordance with t...

Страница 5: ...low this symbol to avoid possible death or injury Indicates an imminently hazardous situation which if not avoided will result in death or serious injury Indicates a potentially hazardous situation which if not avoided could result in death or serious injury Indicates a potentially hazardous situation which if not avoided could result in minor or moderate injury Caution used without the safety ale...

Страница 6: ...6 Desert Aire LW Manual ...

Страница 7: ...eration Modes 20 3 2 1 Dehumidification Air Reheat Optional Outdoor Air 21 3 2 2 Dehumidification Air Cooling Remote Ready Units Only 21 3 2 3 Evaporator Defrost Mode 22 3 2 3 1 Defrost Cycle Settings 22 3 2 4 Pump Down Cycle 22 3 2 5 Blower Operation 22 3 3 Refrigeration Testing 23 3 4 General Testing 24 3 5 Routine Maintenance Schedule 25 3 5 1 Service Every Month 25 3 5 2 Service Every Six Mont...

Страница 8: ... Airflow 38 5 3 1 2 Blower Adjustment Procedure 38 5 3 2 Unit Operation 40 5 3 2 1 Controller Set Points 40 5 3 2 2 Refrigeration System Pressures 40 5 4 Component Replacement Charge Evacuation Leak Instructions 41 5 5 Rating Plate 45 5 6 System Start Up Report 45 Service Bulletin 027 46 LW Series Start Up Report 48 LW Series Compressor Replacement Form 52 Desert Aire LW Manual ...

Страница 9: ... have not filled out within a week of delivery Notify Desert Aire of any damage 1 3 Rigging 1 Failure to observe rigging instructions may lead to equipment damage personal injury or death 2 Lifting method and procedure must comply with all local and national codes and regulations 3 The use of safety slings in addition to lifting lugs is required 4 Do not lift the dehumidifier in high winds or abov...

Страница 10: ... on its side 2 Avoid dropping the unit down stairways or subjecting it to severe mechanical shock 1 3 2 Rigging the Remote Condenser Refer to separate Remote Condenser Manual for specifications regarding rigging Desert Aire LW Manual ...

Страница 11: ... Never install the dehumidifier on a wooden platform without consulting the design engineer for spring isolation requirements and sound control materials Do not install the unit near occupied rooms such as offices or guestrooms Do not attempt to conserve installation space by fabricating restrictive ductwork with abrupt bends You may reduce the operating efficiency and the moisture removal capacit...

Страница 12: ...ately 12 feet above the ice surface and be equipped with a small section of discharge duct see Figure 3 for layout If you must install the dehumidifier outside you must use an outdoor rated dehumidifier Desert Aire seals and weatherproofs outdoor dehumidifiers to help prevent water infiltration You can determine whether your dehumidifier is outdoor rated by inspecting the unit rating plate see sec...

Страница 13: ...on and noise Figure 4 Standard Unit Airflow Specifications Install the return air grilles or openings as high as possible in the room In most cases one centrally located return air grille will be adequate To prevent air short cycling do not install the return air grille too close to a supply grille Grille sizing is also important Select the grilles registers and diffusers for low static pressure l...

Страница 14: ...e condensate drain pipe to prevent condensate from being drawn into the cabinet of the dehumidifier which may lead to premature corrosion and property damage 2 Condensate drain lines installed in an unconditioned space must be heat taped to prevent freezing Check the heat tape yearly before winter operation You must raise the dehumidifier at least 12 inches above the floor to provide clearance for...

Страница 15: ...consult Desert Aire for help in resizing the P trap You may also need to install a cleanout tee or plug near the trap Note that the drain opening in the drain pan is off center to simplify its cleaning and servicing Once you have designed and installed the trap follow this sequence 1 Connect the trap to a main drain line with 1 4 of downward pitch per linear foot of run 2 Support the drain pipe ev...

Страница 16: ...le phase units mounted on the electrical panel Test the phasing of the three phase unit by bumping the blower contactor Verify that the blower rotates in the proper direction If it rotates the wrong direction Three phase wiring Switch any two of the three wires at the power block Single phase wiring The motor must be re wired according to wiring diagrams included with the motor 2 4 1 High Voltage ...

Страница 17: ...anual for controller and sensor specifications operation and options You will need to run low voltage wires from the controller to the humidity sensor and to the dehumidifier The low voltage wiring diagram located on the inside of the dehumidifier s electric box door shows where to make wiring connections to the system 2 6 Remote Condenser Optional Important Refer to the separate Air Cooled Conden...

Страница 18: ...5 100 0 25 25 50 50 75 75 100 0 25 25 50 50 75 75 100 0 25 25 50 50 75 75 100 0 25 25 50 50 75 75 100 0 25 25 50 51 75 75 100 5 8 5 8 3 4 3 4 3 4 7 8 7 8 7 8 7 8 7 8 1 1 8 1 1 8 7 8 1 1 8 1 1 8 1 1 8 7 8 1 1 8 1 1 8 1 1 8 1 1 8 1 1 8 1 3 8 1 3 8 1 2 1 2 1 2 1 2 1 2 5 8 5 8 5 8 1 2 5 8 5 8 3 4 5 8 5 8 3 4 3 4 5 8 3 4 3 4 3 4 5 8 3 4 7 8 7 8 Standard Remote Condenser Line Sizes and Additional Charge...

Страница 19: ...voltage printed on the rating plate With the power supply disconnected and locked tighten all field and factory electrical connections Check and adjust the belt tension for proper deflection at the mid point of the blower belt s See Figure 10 The deflection is based on the belt length The belt length can be found on the belt itself Determine the force using the Belt Deflection table in Figure 11 I...

Страница 20: ...2 Belts 5 6 8 9 New Belt Force lbs Used Belt Force lbs 1 Belt 2 2 5 5 6 9 10 3 Belts 8 9 Figure 11 Belt Deflection Force Table 3 2 System Operation Modes OPTIONAL O A Box with 2 Position Damper F I L T E R F I L T E R F I L T E R COMPRESSOR Hot Gas Reheat Coil Condensate Drain Evaporator Coil OPTIONAL Temperature Sensor Humidity Sensor OPTIONAL Remote Condenser Figure 12 LW Options that Impact Sys...

Страница 21: ...be introduced if the unit is equipped with an optional outdoor air box In the occupied mode the outdoor air damper opens and the evaporator bypass damper closes to keep a constant airflow An exhaust fan dry contact then turns on the external exhaust fan In unoccupied times the outdoor air damper closes and the evaporator bypass damper opens to maintain constant airflow Exhaust fan and damper dry c...

Страница 22: ... determine an optimal setting for your application Do not deviate from factory settings unless you monitor the system closely 3 2 4 Pump Down Cycle LW series dehumidifiers are factory wired for pump down This effectively reduces the likelihood of liquid refrigeration build up in the low side of the system during the off cycle Whenever there is power to the unit the compressor will become energized...

Страница 23: ... commissioned The design and processing of the field piping is just as important as the factory piping in ensuring the longevity of the system Selection of quality components quality procedures and full testing help to ensure the sealed system failures are minimized wherever possible Nonetheless the mechanical nature of many components creates some unforeseen wear and failure in certain instances ...

Страница 24: ...hart Temp F 45 1 50 0 13 14 14 15 15 50 1 55 0 14 15 15 15 16 60 1 65 0 15 16 18 18 19 55 1 60 0 15 15 16 16 18 65 1 70 0 16 18 18 19 20 Relative Air Humidity RH Relative Air Temperature F Figure 14 Superheat Minimum Values Chart 3 4 General Testing After you balance the airflow and test the refrigeration circuits verify that the other equipment and accessories connected to the dehumidifier work p...

Страница 25: ...hould energize 3 5 Routine Maintenance Schedule 3 5 1 Service Every Month Check the air filters and replace them if necessary Check the coils in the dehumidifier and the remote condenser Use compressed air or a commercial coil cleaner if they are dirty or plugged Verify that the air flow around the remote condenser remains unobstructed 3 5 2 Service Every Six Months Check the blower belts for wear...

Страница 26: ...26 Desert Aire LW Manual ...

Страница 27: ... to consult with other contractors who have worked on different portions of this project The following list will help you diagnose some of the most obvious symptoms of a system which does not work properly 4 1 Supply Blower will Not Run POSSIBLE CAUSE System terminal switch in open position Loss of main power Blower overload relay or thermal overload has tripped Blown fuse in electrical circuit De...

Страница 28: ...pressor from activating Operation below 32 F will accelerate system wear and tear and void the warranty REMEDY A Adjust controller set points B On models with a remote condenser installed verify that the condenser is enabled Check for tripped circuit breaker or blown fuses Check for loose or faulty wiring on system and controller Inspect the following A elevated head pressure B lack of oil to the ...

Страница 29: ...1 Evaluate system airflow See Section 5 3 1 1 2 Check for dirty filters or restricted ductwork 3 Assure coils are clean Re evaluate system charge Evaluate filter pressure drop and replace if necessary Evaluate expansion valve performance and replace if necessary 1 Check coil for kinks in tubing 2 Evaluate debris in distributor NOTE The LW series dehumidifier is NOT intended for use below 32 F ambi...

Страница 30: ...ES Lack of airflow Remote condenser fan does not run Refrigeration system is overloaded NOTE LW SERIES DEHUMIDIFIERS ARE DESIGNED FOR A MAXIMUM RETURN AIR TEMPERATURE OF 70 F Assure remote condenser coil is clean and no airflow restrictions exist around unit A Overload is a thermo protector Allow to cool to reset If multiple trips occur verify amp draw and replace motor if necessary A Overload tri...

Страница 31: ... supply registers windows heaters saunas etc 2 Consider continuous blower operation Evaluate charge 4 6 Frost Build up on the Compressor or Suction Line NOTE Thermal expansion valves on LW series dehumidifiers must be set to maintain a proper superheat at the evaporator Frost build up on the suction lines or the compressor can indicate lack of superheat Lack of superheat will create the damaging p...

Страница 32: ...32 Desert Aire LW Manual ...

Страница 33: ...ompressors are known for operating more reliably than other compressors in air conditioning and dehumidification applications due to their ability to cope with occasional periods of liquid refrigerant return There are fewer moving parts in a scroll compressor subject to wear compared to alternative compressor designs Nonetheless there are still many mechanical and electrical parts with close toler...

Страница 34: ...ts of the system before completing the compressor replacement Compressor Replacement Refrigeration oil must be tested for acid and particulate during any compressor replacement For the initial testing the compressor sump should be used to sample the oil Oil can be recovered through the Schrader port on the low point compressor shell or through the suction line connection after the compressor has b...

Страница 35: ... connect to Schrader fittings Ensure there are access fittings directly upstream and downstream of the suction filter There is typically one fitting installed on the suction filter There may be a bulkhead fitting attached to the compressor suction side Do not use acid neutralizing additives or other chemicals for acid removal The refrigeration system must contain only oil and refrigerant Precipita...

Страница 36: ...ce cores with standard filter elements Remove outlet screens if they were required by filter manufacturer If the pressure differential across the liquid line filter is 5 PSI or greater replace cores and secondary filter with new components and test at 24 hour intervals until pressure drop is at acceptable levels Once pressure differential is less than 5 PSI remove secondary filter and replace core...

Страница 37: ...erates effectively and without problems Undersized or restrictive ducts reduce the system airflow which can cause premature compressor failure Use the following diagrams as a guide when you design the duct system Figure 15 Recommended Duct Designs for Desert Aire Dehumidifiers Desert Aire LW Manual ...

Страница 38: ...ntial gauge determine the static pressure drop in inches water column across the unit s condenser coil Units are equipped with pressure tap holes on the side panels just for this purpose See Figure 4 for proper pressure drop range for your unit A low static pressure drop indicates low airflow you must speed up the blower A high pressure drop indicates high airflow you must slow down the blower NOT...

Страница 39: ...Aire Dehumidifier is designed to operate at a specified airflow rate Airflow must be set prior to starting the refrigeration circuit to assure that problems are not caused by improper unit airflow Using a manometer or Magnehelic pressure differential gauge determine the pressure drop in inches water column in WC across the unit s condenser coil Units are equipped with pressure tap holes on the sid...

Страница 40: ...t to establish equilibrium at a given set point Therefore continued set point adjustments will lead to high energy consumption and user discomfort SPACE PRESSURIZATION Assure that doors and windows are sealed adequately to prevent infiltration of warm humid air A positive pressure in the controlled environment is strongly recommended Only introduce required amounts of outdoor air when mandated by ...

Страница 41: ...ecover independently to avoid refrigerant contamination Uncontaminated refrigerant can be reused in the refrigeration system it was recovered from Recovery of Systems without a Leak Systems that do not have leaks but still require refrigeration system service may have charge isolated in receivers and condensers if these particular components do not require direct service Desert Aire dehumidifiers ...

Страница 42: ...that phosphorous bearing alloys be considered for copper to copper connections due to their self fluxing on copper to copper joints Refer to alloy manufacturer s guidelines to details on compatibility Flow nitrogen into tubing to prevent the formation of copper oxides Copper oxides form rapidly when copper is heated to temperatures required by the brazing process and exposed to oxygen in the air C...

Страница 43: ... can be held for a minimum of 10 minutes Alternative Evacuation Specified by Process After components have been repaired or replaced evacuation procedure should take place Very small amounts of refrigerant may still be mixed with the oil in the system Out gassing of this refrigerant may interfere with the evacuation and vacuum decay testing IF AND ONLY IF a unit has been previously charged with re...

Страница 44: ...e unit should not be used for charge addition Monitor superheat at the compressor suction inlet using the bulkhead fitting and a temperature sensor on the suction line near the compressor Superheat should not drop below 10 degrees during the process of adding charge Testing and Final Diagnosis Check the oil level in the compressor after the system has been running for 24 hours Oil may have been co...

Страница 45: ...ut thoroughly by a qualified service technician and returned to Desert Aire for warranty validation Please ensure that the model and serial number of the unit are noted on this form The model and serial number can be found on the system s rating plate located on or near the electrical compartment service door Failure to complete and return this form will void the unit s warranty These reports are ...

Страница 46: ...rt Up Equipped service vehicle and service technician Technician will be trained Refrigerant manifold gauges 2 sets Air balancing equipment Magnehelic or manometer differential pressure gauge Volt Amp OHM meters in working order Digital thermometer w clamp on sensors OR laser type temperature probe 50 of refrigerant see order specs for refrigerant types weigh in scale Hand pump for adding oil to c...

Страница 47: ...___________ Phone _____________________________________ Jobsite Information Jobsite Address __________________________________________________________________________________ __________________________________________________________________________________ Jobsite Contact ______________________________________ Cell ______________________________________ Jobsite Phone _____________________________...

Страница 48: ...ical components and refrigeration under pressure are present Before continuing read the Installation and Operations manual If you do not fully understand the manual contact the Desert Aire Service Department Please be prepared with the model and serial numbers located on the rating plate of the unit Use one start up report per unit Print or type all information If there is not enough space availab...

Страница 49: ...Additional Oil Added OZS Flush Cycle Enabled Yes No Fan Cycle Controller Settings Refer to Air Cooled Condenser manual for instructions SENS SN 1 SN 2 SN 3 OUTR1 ON 1 OFF 1 ONT 1 OFT 1 SNF 1 SENS 1 OUTR2 ON 2 OFF 2 ONT 2 OFT 2 SNF 2 SENS 2 OUTR3 ON 3 OFF 3 ONT 3 OFT 3 SNF 3 SENS 3 OUTR4 ON 4 OFF 4 ONT 4 OFT 4 SNF 4 SENS 4 Proper Installation Checklist Installation manual read and understood Tighte...

Страница 50: ...s Actual L1 L2 L3 Blower Control Set to Continuous Operation or Automatic Operation Continuous Auto Temperature Readings Room Air Temperature F Room Relative Humidity F Outdoor Air Temperature F Outdoor Relative Humidity F Compressors and Refrigeration in Reheat Mode Motor Compressor RLA off nameplate amps amps Amperage L1 L1 L2 L2 L3 L3 Head Pressure Psig Suction Pressure Psig Refrigerant Sight G...

Страница 51: ...s Discharge Air Temp Electric Heater F Auxiliary Water Steam Coil Information Signal Inlet Temp Outlet Temp Discharge Air Temp Water Coil F F F Compressors and Refrigeration in Cooling Mode Remote or Tower Water Condenser Head Pressure Psig Suction Pressure Psig Refrigerant Sight Glass Clear Yes No Superheat F Subcooling F Compressor Oil Level Sight Glass level should be at least 3 4 full at compl...

Страница 52: ... more legs Compressor drawing higher current than design Continuity 0 resistance between two or more legs 3 phase units Compressor drawing locked rotor current Other describe Runs without pumping Pressures _____ _____ Final Determination of Failure Liquid Floodback Low Superheat Debris Defective Expansion Valve Low Sump Oil Insufficient Motor Cooling Other Describe Diagnostic Corrective Action Sum...

Страница 53: ...Circuit B Use both sides for tandem set Motor See wiring schematic for details Discharge Pressure PSIG PSIG PSIG PSIG Liquid Line Pressure At access fitting nearest TXV PSIG PSIG PSIG PSIG Suction Pressure At compressor PSIG PSIG PSIG PSIG Liquid Line Temperature At access fitting nearest TXV F F F F Suction Temperature At Compressor F F F F Refrigerant Sight Glass Condition Clear Intermittent Vap...

Страница 54: ...2017 09 Optimizing Solutions Through Superior Dehumidification Technology N120 W18485 Freistadt Road Germantown WI 53022 E mail info desert aire com Ph 262 946 7400 Fax 262 946 7401 Website www desert aire com ...

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