Quest dehumidifiers (often shortened to "Quest dehu") are commercial machines from Quest Climate. They are rated at the AHAM condition of 80F and 60% RH and published with an efficiency figure in pints per kWh, which makes them easy to compare with each other. They are not comparable with a home dehumidifier's DOE rating at 65F.
Most Quest models are sold through hydroponics stores and HVAC suppliers rather than big-box retailers. The Quest 155 and 225 are overhead "Dual" units designed to hang from a ceiling; the 335 and 506 are larger; the Hi-E Dry 195 is a portable unit on wheels.
| Model | Pints/day (80F, 60% RH) | Efficiency | Power | Type |
|---|---|---|---|---|
| Quest 155 | 155 | 8.5 pints/kWh | Not listed here | Overhead |
| Quest 225 | 225 | 6.3 to 8.2 pints/kWh (varies by version and source) | 208 to 230 V, about 5.5 to 6.1 A | Overhead |
| Quest 335 | 335 (some listings say about 350) | 9.3 pints/kWh | Not listed here | Large |
| Quest 506 | 506 | 8.1 pints/kWh | 220 to 240 V, 11 A, 2,700 W | Large |
| Quest Hi-E Dry 195 | 195 | 6.1 pints/kWh (A2L version) | 115 V, about 12 A | Portable |
Sources: Quest brochure and spec sheets; Sylvane and Hydrobuilder listings. Quest has updated several models for newer A2L refrigerants, which changed some figures; check the sheet for the version you buy.
Quest models compared
| Pick | Capacity | Coverage | Pump | Noise | ENERGY STAR | Price tier | |
|---|---|---|---|---|---|---|---|
| Quest 225 Quest 225 | 225 pints/day (AHAM 80F) | Not stated | Not stated | Not published | Not stated | $$$$$ | Check price |
| Quest 506 Quest 506 | 506 pints/day (AHAM 80F) | Not stated | Not stated | Not published | Not stated | $$$$$ | Check price |
| Quest 335 Quest 335 | 335 pints/day (AHAM 80F) | Not stated | Not stated | Not published | Not stated | $$$$$ | Check price |
| Quest 155 Quest 155 | 155 pints/day (AHAM 80F) | Not stated | Not stated | Not published | Not stated | $$$$$ | Check price |
| Quest Hi-E Dry 195 Quest Hi-E Dry 195 | 195 pints/day (AHAM 80F) | Not stated | Not stated | Not published | Not stated | $$$$$ | Check price |
Quest 225
The Quest 225 dehumidifier removes 225 pints a day at 80F and 60% RH. It is an overhead unit, so it hangs above a grow room canopy or in a ceiling space, and it runs on 208 to 230 V, so it needs a dedicated circuit. Published efficiency varies by version: one listing gives 6.3 pints per kWh at AHAM conditions, another 7.6, and a Quest-linked retailer says the newer high-efficiency 225 reaches 8.2. If you are comparing quotes, ask which version and refrigerant you are getting.
Heads up: Sold mainly through hydroponics and HVAC suppliers; the Amazon link searches for it.
| Model number | 225 |
|---|---|
| Type | Commercial compressor (high capacity) |
| Capacity (AHAM test, 80F, 60% RH) | 225 pints/day |
| Coverage | Not stated by maker |
| Built-in pump | Not stated |
| Wi-Fi / app | Not stated |
| ENERGY STAR | Not stated |
| Noise | Not published |
| Efficiency | Sources differ: 6.3 to 8.2 pints/kWh depending on version |
| Power | 208 to 230 V, about 5.5 to 6.1 A (Hydrobuilder listing) |
| Mounting | Overhead (Quest Dual series) |
| Price tier | Pro (about $900 and up) |
Pros
- High capacity in a compact overhead unit
- Efficient for its class
Cons
- Needs 208 to 230 V
- Efficiency varies by version
Spec sources (checked 2026-11-12): Quest Indoor Farming brochure; Sylvane: Quest 225 high-efficiency dehumidifier; Hydrobuilder: Quest 225 listing.
Quest 506
Quest 506 Dehumidifier
The Quest 506 dehumidifier is the big one: 506 pints a day at 80F and 60% RH and 8.1 pints per kWh. Its installation manual lists 220 to 240 V, 11 A and 2,700 W. It suits large flowering rooms and warehouses where one 506 replaces several smaller units.
Heads up: Sold mainly through hydroponics and HVAC suppliers; the Amazon link searches for it.
| Model number | 506 |
|---|---|
| Type | Commercial compressor (high capacity) |
| Capacity (AHAM test, 80F, 60% RH) | 506 pints/day |
| Coverage | Not stated by maker |
| Built-in pump | Not stated |
| Wi-Fi / app | Not stated |
| ENERGY STAR | Not stated |
| Noise | Not published |
| Efficiency | 8.1 pints/kWh at 80F, 60% RH |
| Power | 220 to 240 V, 11 A, 2,700 W (installation manual) |
| Price tier | Pro (about $900 and up) |
Pros
- Very high capacity
- One unit instead of several
Cons
- 2,700 W
- Needs a 240 V circuit
Spec sources (checked 2026-11-12): Quest Indoor Farming brochure; Sylvane: Quest 225 high-efficiency dehumidifier; Hydrobuilder: Quest 225 listing.
Quest 335
Quest 335 Dehumidifier
The Quest 335 dehumidifier is rated at 335 pints a day at 80F and 60% RH and 9.3 pints per kWh in Quest's brochure, the highest efficiency figure in this group. Some listings give about 350 pints, likely a version difference.
Heads up: Sold mainly through hydroponics and HVAC suppliers; the Amazon link searches for it.
| Model number | 335 |
|---|---|
| Type | Commercial compressor (high capacity) |
| Capacity (AHAM test, 80F, 60% RH) | 335 pints/day |
| Coverage | Not stated by maker |
| Built-in pump | Not stated |
| Wi-Fi / app | Not stated |
| ENERGY STAR | Not stated |
| Noise | Not published |
| Efficiency | 9.3 pints/kWh at 80F, 60% RH (Quest brochure) |
| Note | Some listings give about 350 pints/day |
| Price tier | Pro (about $900 and up) |
Pros
- Highest published efficiency here
Cons
- Large and heavy
- Pro install
Spec sources (checked 2026-11-12): Quest Indoor Farming brochure; Sylvane: Quest 225 high-efficiency dehumidifier; Hydrobuilder: Quest 225 listing.
Quest 155
Quest 155 Dehumidifier
The Quest 155 dehumidifier is the smallest overhead model: 155 pints a day at 80F and 60% RH and 8.5 pints per kWh, per its listing. It fits smaller rooms where a 225 would cycle on and off too often.
Heads up: Sold mainly through hydroponics and HVAC suppliers; the Amazon link searches for it.
| Model number | 155 |
|---|---|
| Type | Commercial compressor (high capacity) |
| Capacity (AHAM test, 80F, 60% RH) | 155 pints/day |
| Coverage | Not stated by maker |
| Built-in pump | Not stated |
| Wi-Fi / app | Not stated |
| ENERGY STAR | Not stated |
| Noise | Not published |
| Efficiency | 8.5 pints/kWh at 80F, 60% RH (Sylvane listing) |
| Mounting | Overhead (Quest Dual series) |
| Price tier | Pro (about $900 and up) |
Pros
- Efficient
- Overhead
Cons
- Smaller capacity
Spec sources (checked 2026-11-12): Quest Indoor Farming brochure; Sylvane: Quest 225 high-efficiency dehumidifier; Hydrobuilder: Quest 225 listing.
Quest Hi-E Dry 195
Quest Hi-E Dry 195 Portable Dehumidifier
The Hi-E Dry 195 is Quest's portable unit on wheels, rated at 195 pints a day at 80F and 60% RH, with 610 CFM of airflow. Its spec sheets also give lower figures at cooler conditions: 160 pints at 70F and 60% RH and 120 pints at 70F and 50% RH, which is a useful reminder of how much capacity drops as conditions get drier. It runs on 115 V.
Heads up: Sold mainly through hydroponics and HVAC suppliers; the Amazon link searches for it.
| Model number | Hi-E Dry 195 (4046400 A2L version) |
|---|---|
| Type | Commercial compressor (high capacity) |
| Capacity (AHAM test, 80F, 60% RH) | 195 pints/day |
| Coverage | Not stated by maker |
| Built-in pump | Not stated |
| Wi-Fi / app | Not stated |
| ENERGY STAR | Not stated |
| Noise | Not published |
| Capacity at other conditions | 160 pints at 70F, 60% RH; 120 pints at 70F, 50% RH (older spec sheet) |
| Efficiency | 6.1 pints/kWh (A2L version spec sheet); older version 4.9 to 5.4 |
| Power | 115 V, about 12 A (A2L version) |
| Airflow | 610 CFM |
| Price tier | Pro (about $900 and up) |
Pros
- Portable
- 115 V
- Published capacity at several conditions
Cons
- About 12 A draw
- Lower efficiency than the overhead units
Spec sources (checked 2026-11-12): Quest Hi-E Dry 195 spec sheet (A2L, 4046400); Quest Climate: Hi-E Dry 195.
Quest 225 vs 506
| Quest 225 | Quest 506 | |
|---|---|---|
| Capacity (80F, 60% RH) | 225 pints/day | 506 pints/day |
| Efficiency | 6.3 to 8.2 pints/kWh | 8.1 pints/kWh |
| Voltage | 208 to 230 V | 220 to 240 V |
| Best for | One mid-size room | Large rooms and warehouses |
Two 225s give you redundancy and can be placed at opposite ends of a room; one 506 is simpler to install and maintain. Growers often size from the room's water load (how much the plants transpire per day) rather than square footage.
Pros and cons of Quest
| Pros | Cons |
|---|---|
| High capacity and published efficiency | Not sold at most retailers; Amazon links search for them |
| Overhead models save floor space | Most need 208 to 240 V circuits |
| Used widely in grow rooms | Pro price tier; specs vary between versions |
Verdict
For a commercial grow room, Quest units are a standard choice, and the 225 is the middle of the range. For a home basement, they are usually overkill: a heavy duty unit like those in our commercial dehumidifier guide runs on a normal 115 V outlet. See our grow room guide for tent-sized options.
Frequently asked questions
Are Quest dehumidifiers worth it?
Quest 225 vs 506?
Where are Quest dehumidifiers made?
Sources
- Quest Indoor Farming brochure
- Quest Hi-E Dry 195 spec sheet (A2L)