Quest Engineering 335 Manual

INSTALLATION, OPERATION AND
MAINTENANCE INSTRUCTIONS
QUEST
335
QUESTCLIMATE.COM / [phone]
Patents: thermastor.com/patents
Serial Number
Install Date
Sold By
TS-1196 05/22 REV A
Digital controls
Long-life impeller
230V & 277V units
Industry-leading efficiency
Superior MERV-13 air filtration
Filter Compensation Technology
Auto-restart after power outages

2
QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
TABLE OF CONTENTS
Safety Precautions............................................................3
1. Intended Application....................................................4
2. Registrations .................................................................4
3. Specifications................................................................4
4. Installation .....................................................................5
4.1 Location...................................................................5
4.2 Electrical Requirements .....................................5
4.3 Condensate Water Removal ...............................6
4.4 Hanging Diagram .................................................7
4.5 Hard-Wiring Instructions ....................................8
4.6 Supply & Return Duct Kit ................................. 11
5. Control Options........................................................... 12
5.1A On Board Dehumidistat ............................ 12
5.2B External Control Options......................... 13
5.2 External Control.................................................. 14
6. Maintenance ................................................................ 14
6.1 Standard Air Filter............................................... 14
6.2 Impeller Fan Oiling ............................................. 14
7. Service.......................................................................... 15
7.1 Warranty................................................................. 15
7.2 Technical Description......................................... 15
7.3 Troubleshooting................................................... 15
7.4 Refrigerant Charging.......................................... 17
7.5 Impeller Fan Replacement................................. 17
7.6 Compressor/Capacitor Replacement .............. 17
7.6A Checking Compressor Motor Circuits ... 17
7.6B External Control Options ......................... 18
7.6C Replacing Compressor-Nonburn Out..... 19
7.7 Remote Controls.................................................. 19
7.7A Humidity Control ....................................... 17
7.8 Defrost Thermostat ............................................. 19
7.9 Condensate Pump Kit......................................... 19
8. Error Codes................................................................. 20
Wiring Diagram................................................................. 21
Service Parts List ........................................................... 22
Optional Parts List ......................................................... 22
Warranty......... .................................................................. 24
4201 Lien Rd. Madison, WI 53704
1-800-533-7533
Thermastor.com | QuestClimate.com
© 2016 Therma-Stor LLC

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
SAFETY PRECAUTIONS
Read the installation, operation and maintenance instructions carefully before installing and
operating this device. Proper adherence to these instructions is essential to obtain maximum benefit
from your Quest Dehumidifier.
READ AND SAVE THESE INSTRUCTIONS
• The device is designed to be installed INDOORS IN A SPACE THAT IS
PROTECTED FROM RAIN AND FLOODING.
• Install the unit with space to access the back or side panels for
maintenance and service. DO NOT INSTALL UNIT WITH THE SERVICE
PANELS INACCESSIBLE.
• Avoid directing the discharge air at people, or over the water in pool
areas.
• If used near a pool, spa or water; be certain there is NO chance the unit
could fall into the water, be splashed and that it is plugged into an outlet
that is a GROUND FAULT INTERRUPT protected circuit.
• DO NOT use the device as a bench or table.
• DO NOT place the device directly on structural members. Provide vibration
isolation in order to minimize operational vibration and/or noise.
• A drain pan MUST be placed under the unit if installed above a living area
or above an area where water leakage could cause damage
• Never operate a unit with a damaged power cord. If the power cord is
damaged it must be replaced by the manufacturer, its service agent, or
similarly qualified person in order to avoid a hazard.
• Make all electrical connections in accordance with the current edition of
the NEC ANSI/NFPA 70 and any national and local codes or ordinances
that may apply.
• Maintain a minimum 1ft. (.3m) clearance to avoid obstructing the air return
and supply.
• This appliance is not intended for use by persons (including children) with
reduced physical, sensory or mental capabilities, or lack of experience
and knowledge, unless they have been given supervision or instruction
concerning use of the appliance by a person responsible for their safety.
Children should be supervised to ensure that they do not play with the
appliance.
• Not intended for use at altitudes over 6500 ft (2000M).

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
1. INTENDED APPLICATION FOR QUEST 335
The Quest 335 Dehumidifier is designed to operate in temperatures between 56° and 95°F.
In order to efficiently control humidity levels, the area in which the dehumidifier is to be operated must
be free of water intrusion or excessive fresh (outside) air infiltration. Before installing the Quest 335
Dehumidifier, water intrusion and air infiltration problems should be addressed or noted in calculations.
2. REGISTRATIONS
The Quest 335 Dehumidifier units conform to unified standard UL 60335-2-40, CSA C22,2#60335-2-40.
US Patents: D570,988 / 8,069,681 / 9,052,132.
3. SPECIFICATIONS @ 80°F/60% RH
UNIT QUEST 335
4042500 QUEST 335 277V 4042600
BLOWER:
(TESTED WITH DUCT
COLLARS ON)
900 CFM @ 0.6” WG 900 CFM @ 0.6” WG
POWER: 1565 Watts 1789 Watts
SUPPLY VOLTAGE: 208V and 230V -
1 Phase - 60 Hz
277V -
1 Phase - 60 Hz
CURRENT DRAW: 6.9A @ 230V
7.9A @ 208V 6.8A @ 277V
ENERGY FACTOR: 4.4 L/kWh 4.0 L/kWh
OPERATING TEMP: 56 F Min–95 F Max 56 F Min–95 F Max
WATER REMOVAL:
EFFICIENCY:
350 Pints/Day
9.3 Pints/kWh
350 Pints/Day
8.5 Pints/kWh
AIR FILTER: MERV-13 Size: 22” x 20” x 2” MERV-13 Size: 22” x 20” x 2”
POWER CORD:
10’ 14/3 SJTW
NEMA 6-15P NEMA L7-15P
DRAIN
CONNECTION: 3/4” Threaded NPT 3/4” Threaded NPT
REFRIGERANT TYPE:
REFRIGERANT
AMOUNT:
R410A
4 lb 12 oz
R410A
4 lb 12 oz
DIMENSIONS:
WIDTH:
HEIGHT:
LENGTH:
WEIGHT:
Unit Shipping
32.88” 36”
24.38” 30”
23.5” 28”
215 lb 255 lb
Unit Shipping
32.88” 36”
24.38” 30”
23.5” 28”
215 lb 255 lb

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
4. INSTALLATION
4.1 LOCATION
The Quest 335 Dehumidifier can be installed in a variety of locations to meet the owner’s needs as
listed below. In all cases keep the following cautions in mind:
• Place the Quest 335 Dehumidifier on supports that raise the base of the unit 6” above the
secondary drain pan so a P-trap can be installed. See Section 4.3.
• The Quest 335 Dehumidifier may be suspended with steel hanger, straps, or a suitable alternative
from structural members, unit must be supported from underneath. Don’t hang from sides or
ends. See section 4.4
• If installing on ground, use included plugs to cover hanging locations on top of the machine.
• If hanging machine in air, use included plugs to cover holes in base pan for leveling feet.
4.2 NO DUCTING (FIG. 1)
The Quest 335 Dehumidifier plugs into NEMA rated receptacles. The amp draws for each unit under
normal operating conditions are listed on page 4. A ground fault interrupter protected circuit is
required.
Install the remote hygrostat in a central area of the structure where it will sense the relative
humidity of the structure accurately. Do not install the hygrostat where it may not accurately sense
the relative humidity such as near HVAC supply registers, near exterior doors, or near a pool or spa.
The installer must supply the wiring between the Quest 335 Dehumidifier and the hygrostat. Be sure
to safely route the control wiring to prevent damage during installation. Be careful not to cross the
wires when connecting the Quest 335 Dehumidifier and the remote hygrostat.
The remote controls of the Quest 335 Dehumidifier are powered by a low voltage circuit (24 VAC)
and must NEVER contact or be connected to a high voltage circuit. The control terminals and remote
control are labeled and numbered to prevent confusion. Be sure to consult the electrical schematic
in this manual or inside the access panel of the Quest 335 Dehumidifier before making the control
connections.
CAUTION! Always disconnect the Quest 335 from a power source when
working with the high voltage control wires.
UNIT QUEST 335
4042500 QUEST 335 277V 4042600
BLOWER:
(TESTED WITH DUCT
COLLARS ON)
900 CFM @ 0.6” WG 900 CFM @ 0.6” WG
POWER: 1565 Watts 1789 Watts
SUPPLY VOLTAGE: 208V and 230V -
1 Phase - 60 Hz
277V -
1 Phase - 60 Hz
CURRENT DRAW: 6.9A @ 230V
7.9A @ 208V 6.8A @ 277V
ENERGY FACTOR: 4.4 L/kWh 4.0 L/kWh
OPERATING TEMP: 56 F Min–95 F Max 56 F Min–95 F Max
WATER REMOVAL:
EFFICIENCY:
350 Pints/Day
9.3 Pints/kWh
350 Pints/Day
8.5 Pints/kWh
AIR FILTER: MERV-13 Size: 22” x 20” x 2” MERV-13 Size: 22” x 20” x 2”
POWER CORD:
10’ 14/3 SJTW
NEMA 6-15P NEMA L7-15P
DRAIN
CONNECTION: 3/4” Threaded NPT 3/4” Threaded NPT
REFRIGERANT TYPE:
REFRIGERANT
AMOUNT:
R410A
4 lb 12 oz
R410A
4 lb 12 oz
DIMENSIONS:
WIDTH:
HEIGHT:
LENGTH:
WEIGHT:
Unit Shipping
32.88” 36”
24.38” 30”
23.5” 28”
215 lb 255 lb
Unit Shipping
32.88” 36”
24.38” 30”
23.5” 28”
215 lb 255 lb

6
QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
CAUTION! For proper drainage, the unit must be mounted so the drain outlet
is at least 6.75” above the floor drain, and must be fully supported under the base.
4.3 CONDENSATE WATER REMOVAL
Condensate drains by gravity via the drain port. Use 3/4” male NPT PVC pipe. An optional condensate
pump kit may be installed if a lift is required to dispose of the condensate. Optional parts list for
information on the kit.
FOLLOW DIAGRAM:
QUEST 335
H = 4”
J = 2”
L = 6.75”
Vent:
• Place vent after the trap.
• Vent should be open.
• Height of vent should be higher than drain outlet.
Cap:
• A clean out can be placed before trap but must be sealed with a cap.
Drain Line:
• Drain line should go in a downward slope to the drain.
• 1/4” drop per foot.
L
H
J
Drain Trap Configuration
VENT OPEN
CAP

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
4.3 HANGING DIAGRAM
QUEST 335
Parts Needed: 4 pieces 3/8” threaded rod (not included)
4 - 3/8” threaded jam nuts (not included)
22.216.6
3/8” threaded rod
Intake Air
Treated Air
3/8” Jam Nuts
Threaded rods should be engaged
no less than 2” into machine.

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
4.5 HARD-WIRING INSTRUCTIONS
WARNING! Servicing the Quest 335 Dehumidifier, with its high pressure
refrigerant system and high voltage circuitry presents a health hazard which could
result in death, serious bodily injury, and/or property damage. Only qualified service
people should service this unit.
TOOLS REQUIRED:
• T25 Torx Driver
• 11/32” Driver
Following all local and national electrical codes and standards, route electrical service to the location
that the dehumidifier will be installed.
Remove 7 screws on access panel using T25 Torx driver, remove panel.

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
Disconnect POWER CORD BLACK wire from terminal
Disconnect POWER CORD WHITE wire from terminal.
Use 11/32” driver to remove nut from ground stud and disconnect POWER CORD GREEN wire from
ground stud.
Remove the 2 screws holding the cord retention bracket using T25 Torx driver and remove retention
bracket.
Remove power cord and black bushing.
Route incoming power service wires through 7/8” hole and secure using clamps intended for the
conduit or cable.
Disconnect
power cord
black wire
Wire harness
black wire
Wire harness
white wire
Disconnect
power cord
white wire
Disconnect
power cord green wire
from ground stud
Remove cord
retention
bracket
Remove
bushing from
7/8” hole

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QUEST 335 INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
QUESTCLIMATE.COM(877) 420-1330
Hardwire kit with jumper wires can be found in the pack part kit.
Connect BLACK and WHITE jumper wires to terminal block as shown.
Place GREEN jumper wire ring terminal on ground stud and use 11/32” driver to secure nut to stud.
Attach incoming service LINE 1 wire to BLACK jumper wire with the provided wirenut.
Attach incoming service LINE 2 wire to WHITE jumper wire with the provided wirenut.
Attach incoming service GROUND wire to GREEN jumper wire with the provided wirenut.
Connect black
jumper wire
Wire harness
Black wire
Wire harness
white wire
Connect white
jumper wire
Green jumper wire to
ground stud