Desert Aire LW Operating instructions

Installation and Operation Manual

• Designed for low

ambient temperatures,

32° to 70°F

• Defrost cycle uses hot

gas bypass to quickly

eliminate frost from

evaporator coils

• Timed defrost cycle

initiated if suction line

temperatures drop

below 30°F

• Heat of rejection can

be delivered directly to

the space or optional

remote condenser

• Units use R-407C

refrigerant

LT System

2

3

Desert Aire - LT Manual

DANGER

ONLY TRAINED, QUALIFIED PERSONNEL SHOULD INSTALL AND/OR SERVICE

DESERT AIRE EQUIPMENT. SERIOUS INJURY, DEATH AND PROPERTY DAMAGE CAN

RESULT FROM IMPROPER INSTALLATION/SERVICE OF THIS EQUIPMENT. HIGH VOLTAGE

ELECTRICAL COMPONENTS AND REFRIGERANT UNDER PRESSURE ARE PRESENT.

Desert Aire Dehumidication Equipment

Standard Limited Warranty

Desert Aire warrants the dehumidifying unit to be free from defects in materials and workmanship subject to the terms,

conditions and limitations stated herein.

TERMS

Desert Aire warrants all components (except as noted) for a period of two (2) years from the date of shipment. This

warranty shall be limited to the supply of new or rebuilt parts for the part which has failed because of defects in

workmanship or material, and does not include the cost for labor, transportation or other costs not herein provided for.

Replaced parts are warranted only for the remaining portion of the original warranty period.

CONDITIONS

The warranty is subject to the following conditions:

1. The unit must be properly installed and maintained in accordance with the Desert Aire

“Installation and Operation Manual” provided with 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

  decienciesareidentiedaWarrantyValidationLetterwillbeissuedthatprovidesallwarranty

  datesandcoverage.Ifinstallationorstart-updecienciesarepresent,thesemustbecorrected

and communicated to Desert Aire in order to activate warranty.

3. This warranty shall not apply to any part that has been tampered with, or has been subject to

misuse, negligence or accident. A warranty can be obtained for altered equipment but only with

written consent from Desert Aire.

4. The following parts and components are excluded from the warranty: belts, lters, driers, fuses and

refrigerant.

5. Refrigerant coils or other components that corrode due to improperly balanced pool chemistry or

corrosive air quality will not be warranted.

6. All replacements or repairs will be FOB Germantown, WI.

7. This warranty shall be null and void if defects or damages result from unauthorized opening of the

refrigerant circuit, tampering with factory set controls, or operating outside the original design

conditions.

8. Desert Aire shall not be liable for labor costs incurred in diagnosing the problem, or the removal

or replacement of the part or parts being repaired.

9. Desert Aire must preauthorize all warranty coverage described herein.

4Desert Aire - LT Manual

ExtendedWarranty:

Your Desert Aire unit may have extended warrantees beyond this Standard Limited Warranty document.

Extended warrantees are only available at the time of the purchase of the original equipment. These extended

warrantees are covered under a separate document and their terms and conditions are separate from this

document. It is mentioned in this document for informational purposes only. Any Extended Warranties will be

identied on the Warranty Validation Letter.

Any and all incidental or consequential damages are expressly excluded from this warranty. 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 specic 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 the aforementioned.

Inquiries regarding warranty matters should be addressed to:

Desert Aire Corp

c/o Service Manager

N120 W18485 Freistadt Road

Germantown, WI 53022

PH: (262) 946-7400

TOLL FREE: (800) 443-5276

FAX: (262) 946-7401

E-MAIL: [email protected]

Additional copies of this manual can be purchased for a nominal fee from Desert Aire. Submit requests to the contact

information listed above.

5

Desert Aire - LT Manual

SafetyLabelsareusedthroughoutthismanual.TheycomplywiththeANSIZ535.4Standard.

Pleasebefamiliarwiththefollowinglabelsandtheirdenitions.

This is the safety alert symbol. It is used to alert you to potential

personal injury hazards. Obey all safety messages that follow 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 alert symbol indicates a

potentially hazardous situation which, if not avoided, could

result in property damage.

6Desert Aire - LT Manual

7

TABLEOFCONTENTS

1. Introduction ...................................................................................................................... 9

1.1 Inspection

............................................................................................

.................... 9

1.2 Freight Damage Claims .......................................................................................... 9

1.3 Rigging ....................................................................................................................... 9

1.3.1 Rigging the Dehumidier ............................................................................. 9

1.3.2 Rigging the Remote Condenser .................................................................. 10

2. Installation ........................................................................................................................ 11

2.1 Location of Dehumidier

.........................................................................................

11

2.2 Duct Installation ...................................................................................................... 13

2.3 Condensate Drain Piping ........................................................................................ 14

2.4 High Voltage Wiring ................................................................................................ 16

2.4.1 High Voltage Connections ......................................................................... 16

2.4.2 Wire and Fuse Sizing ................................................................................. 17

2.5 Controls and Wiring ................................................................................................ 17

2.6 Remote Condenser (Optional) ................................................................................ 17

3. Start-Up Procedures ..................................................................................................... 19

3.1 Preliminary Inspection ............................................................................................ 19

3.2 System Operation Modes ....................................................................................... 21

  3.2.1 Dehumidication/AirReheat/OptionalOutdoorAir................................. 21

  3.2.2 Dehumidication/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 Months .......................................................................... 25

4. Troubleshooting .............................................................................................................. 27

 4.1 SupplyBlowerWillNotRun.................................................................................... 27

 4.2 CompressorWillNotRun...................................................................................... 28

 4.3 EvaporatorCoilDoesNotFullyDefrost................................................................. 29

 4.4 HeadPressureisTooHigh.................................................................................... 30

 4.5 UnitRunsbutExcessCondensateForms............................................................ 31

 4.6 FrostBuild-upontheCompressororSuctionLine............................................... 31

Desert Aire - LT Manual

8

5 Appendix ............................................

...............................................................................

33

 5.1 CompressorFailure...........................

...............................................................

....... 33

  5.1.1CompressorReplacement............................................................................ 33

 5.2 RecommendedDuctDesign.................................................................................. 37

 5.3 SystemGuidelines.................................................................................................. 38

  5.3.1UnitAirow................................................................................................... 38

   5.3.1.1DeterminingSystemAirow......................................................... 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................................................... 41

 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

  LTSeriesStart-UpReport..................................................................................... 48

  LTSeriesCompressorReplacementForm............................................................ 52

Desert Aire - LT Manual

9

1. Introduction

Desert Aire dehumidiers are designed to provide years of reliable service when installed

properly. Read these instructions carefully before you install the dehumidier.

1.1 Inspection

Desert Aire inspects and tests each dehumidier before it leaves the factory so that you receive a

quality piece of equipment. Unfortunately, equipment may become damaged in transit. Inspect

the dehumidier carefully before signing the receiving papers. Check for both visible and

concealed damage. Remove crating and inspect the exterior cabinet for damage. Dented panels,

broken crating or any uids leaking from the unit should be documented upon delivery.

 1.2 FreightDamageClaims

If the dehumidier has been damaged, document the extent of the damage. Take pictures if

possible. Next, obtain a claim form from the carrier. Promptly ll it out and return the form.

Carriers may deny claims that you have not lled 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 above people.

Desert Aire dehumidiers are solidly built and can be very heavy. Avoid personal injury and

damaging the equipment by planning the installation carefully. Use moving equipment whenever

possible.

  1.3.1 RiggingtheDehumidier

Depending upon the unit type, various rigging methods are used to best t the equipment.

Personnel should avoid stepping on the top of the unit. Desert Aire dehumidiers are not

designed to support the weight of a person on all portions of the roof. Damage incurred

through caved or distorted top panels will not be covered under warranty. If you must walk

on the top panels, carefully walk on the edges where structural integrity is greatest.

Desert Aire - LT Manual

10

1. Do not tip the dehumidifier 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 specications regarding

rigging.

Desert Aire - LT Manual

11

2 Installation

 Manualappliestostandardunitcongurationsonly.

 2.1 LocationofDehumidier

Allow a minimum of 36 inches of clearance around all sides of the dehumidier for piping,

duct connections, and service access. Install the unit on a sturdy, level mounting base or a

platform that will prevent vibration and sound transmission. Never install the dehumidier 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 ofces or

guestrooms. Do not attempt to conserve installation space by fabricating restrictive ductwork

with abrupt bends. You may reduce the operating efciency and the moisture removal

capacity of the dehumidier. See section 5.2 for detailed duct installation instructions.

Figure 1 - Typical Floor Installation

Desert Aire - LT Manual

12

Figure 2 - Typical Suspended Installation

For ice rink applications it is recommended that two dehumidiers be installed facing in

opposite directions with the supply airow direction along the rink perimeter. Both units

should be approximately 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 dehumidier outside, you must use an outdoor-rated dehumidier.

Desert Aire seals and weatherproofs outdoor dehumidiers to help prevent water

inltration. You can determine whether your dehumidier is outdoor-rated by inspecting

the unit rating plate (see section 5.5 for details).

Desert Aire - LT Manual

13

Desert Aire - LT Manual

Figure 3 - Typical Ice Rink Installation

2.2 Duct Installation

Duct design and installations should conform to the latest ASHRAE and SMACNA low

velocity duct standards (see section 5.2 for details). Undersized, restrictive ductwork with

abrupt turns or transition can decrease the efciency and the moisture removal capacity of

your dehumidier. Size the ductwork for an acceptable air pressure drop at the airow

volume of your dehumidier. Use neoprene ex connectors when you attach ductwork to the

dehumidier to prevent transmission of excess vibration and noise.

Figure 4 - Standard Unit Airow Specications

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 loss, required throw distance

and the specied CFM rating. You can nd this information in most grille manufacturers’

catalogs. If you are installing the grilles in a corrosive environment, such as an indoor

03

05

08

10 / 12 / 15

1700

2750

4300

6900

External Static Pressure

(Resistance of Ductwork

and Grilles)

0.0” - 1.0” W.C.

LT Model Size Airflow Rate

(CFM)

14

swimming pool, choose components made from anodized aluminum or other

non-corrosive materials.

If you must install ductwork in an unconditioned area, use berglass duct wrap with

vapor barrier facing. You must install the outdoor air intake away from all sources of

airborne contamination such as exhaust fans or plumbing vents. You can use galvanized

sheet metal ducts for most applications. However, you should use aluminum or stainless

steel ducts for extreme applications such as chemical-laden environments.

 2.3 CondensateDrainPiping

1. While the supply blower runs, the inside of the dehumidifier operates

at a negative pressure. Your unit requires a p-trap in the 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 dehumidier at least 12 inches above the oor to provide clearance

for the condensate drain connection. You must supply and install a p-trap on the 1-inch

MPT drain line. Pitch the condensate drain line a minimum of 1/4 inch per linear foot,

and support the pipe with code-approved hangers at least every 5 feet. A cleanout tee

or plug may also be required near the trap to facilitate cleanout. When gravity disposal

is not possible, you may use a condensate pump. Follow the pump manufacturer’s

installation instructions.

Desert Aire - LT Manual

15

Min. 12”

P-Trap (By Others)

Vibration

Isolator

Base /Support

(By Others)

1/4” Slope

Per Foot

Figure 5 - Condensate Piping

4”

Figure 6 - Sectional View of Condensate Trap Requirements

Trap the condensate as shown in Figure 6. The P-trap dimensions in Figure 6 are sized for

a maximum return air static of 2.0” of water. If your return air static exceeds this

specication, 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 every ve feet to prevent sagging.

3. After you install the drain piping, prime the trap by pouring water into the drain pan of

the dehumidier.

Desert Aire - LT Manual

16

 2.4 HighVoltageWiring

1. Disconnect power before servicing. The unit contains high voltage wiring and

moving parts which may cause serious injury or death.

2. Failure to properly wire the dehumidifier may create the possibility of shock and

can lead to premature system failure.

Electrical wiring must comply with all national, state, and local codes. Refer to the

wiring diagram located inside the electrical section for all wiring connections.

To connect main power, attach the supply wires to the three-pole power block for three

phase or two-pole power block for single 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, switch any

two of the three wires at the power block. For a single phase unit the motors must be

re-wired according to the wiring diagrams included with the motor.

  2.4.1 HighVoltageConnections

On single phase units the power supply must have 3 connections

(2 power, 1 ground). On three phase units the power supply must have 4

connections (3 power, 1 ground). Connect the power supply wires to the main

power block located in the upper section of the electrical compartment.

Figure 7 - Single-Phase and Three-Phase System Power Connection

Desert Aire - LT Manual

17

  2.4.2 WireandFuseSizing

The eld-installed power supply wires and overcurrent devices must be sized to

handle the minimum ampacity of the dehumidier without exceeding the maximum

fuse size rating. Both the minimum ampacity and the maximum fuse size are printed

on the unit rating plate.

 2.5 ControlsandWiring

The standard Desert Aire LT Series dehumidiers are controlled by the CM3540

microprocessor controller. This controller is designed for precise monitoring and control of

air temperature and relative humidity (RH) within a conditioned environment. A separate

controls manual has been provided. Refer to this separate manual for controller and sensor

specications, operation, and options.

You will need to run low voltage wires from the controller to the humidity sensor and to the

dehumidier. The low voltage wiring diagram located on the inside of the dehumidier’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 Condensers Installation and Operation manual

for additional details on line design, traps, clamping, and other condenser installation

requirements.

LT dehumidiers installed with remote condensers may require additional oil and refrigerant

charge at the time of eld installation. Refer to the submittal documentation or label adjacent

to the remote condenser connections to conrm the charge and connection tube sizes.

System

Size

Line Size Required (In.)

5/8

7/8

1 1/8

Refrigerant (Lbs.)

Additional refrigerant charge (R-407C) and line size required

(includes condenser charge)

LT03

LT05

LT08

LT10

LT12

LT15

1/2

5/8

15

23

36

30

17

26

40

38

40

Supply (A)Return (B) Up To 25’ 25’ To 50’

Air cooled remote condenser maximum

operating pressure is 375 psi.

Figure 8 - Additional Refrigerant Charge (R-407C) and Line Size Required

Desert Aire - LT Manual

18 Desert Aire - LT Manual

19

3 Start-UpProcedures

Read this section thoroughly before attempting to commission the Desert Aire dehumidier.

A complete start-up will minimize operational problems and expensive callbacks. The start-up

will be quicker and easier if there is a heat and humidity load present in the space. Energize

any auxiliary heaters before start-up so that the air is at the design temperature.

 3.1 PreliminaryInspection

Verify that all contractors have completed their work. Find the Desert Aire “LT Start-Up Report,”

which is normally placed inside this manual within the electrical compartment of the dehumidier.

You must ll out the start-up report to validate the dehumidier warranty. Check the following items:

• Before starting unit, remove wooden shipping blocks found beneath compressor(s).

• Before starting unit, remove shipping restraining brackets on supply blower equipped

with a spring isolation base, if applicable.

• Make sure that the unit is level and securely mounted so that it cannot shift or

transmit vibration to the building.

• Verify that the incoming power supply matches the rating plate of the dehumidier.

The available power supply voltage must be within ±5% of the voltage printed on the

rating plate.

• With the power supply disconnected and locked, tighten all eld and factory electrical

connections.

• Check and adjust the belt tension for proper deection at the mid-point of the blower

belt(s).

• The deection is based on the belt length. The belt length can be found on the belt

itself. Determine the force using the Belt Deection Force table below.

Belt Length

25” to 50”

51” to 70”

71” to 110”

Deflection

0.25”

0.375”

0.625”

Specified Belt Deflection

Figure 9 - Specied Belt Deection Table

Desert Aire - LT Manual

20

HP

0.5

1

1.5

2

3

5

7.5

10

15

20

25

30

40

1 Belt

3

7

12

Belt Deflection Force

2 Belts

7

12

3 Belts

12

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 10 - Belt Deection Force Table

• Inspect the air lters and coils to assure they are clean. If necessary, clean

the coils and install new lters.

• Check the eld and factory piping for leaks. The internal piping may have

been damaged during shipping.

• Purge any air, dirt, or debris from water lines (if used) to avoid clogging the

internal passages of optional heating coils or water side heat exchangers.

• Check the drain pan and the condensate piping. Test the drain and prime the

p-trap by pouring water into the drain pan.

• Verify that all service valves in the refrigeration lines are fully open.

• If you installed a supplemental air heater, make sure you installed it in the air

discharge (or “supply”) duct and not the return duct.

• If your dehumidier has a water heating condenser, turn on the circulating

pump to run water through the system. Inspect the piping and repair any

water leaks you nd.

• After the remote condenser has been installed, enable its operation through

the CM3540 Controller.

Desert Aire - LT Manual

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