Operator's guide to Quest dehumidifiers by Therma-Stor: model capacities, ratings at 75°F and 80°F, power and heat load, and checks for used units.
Quest is a line of commercial refrigerant dehumidifiers made by Therma-Stor LLC, which engineers and assembles the units in Madison, Wisconsin. Quest's own literature dates the brand to 2006, and Therma-Stor, founded in Madison in 1977, sells Quest alongside its Santa Fe, Ultra-Aire and Phoenix lines.
Quest sells into agriculture, food and beverage, storage and industrial sites, and publishes a separate indoor farming catalog for growers. Urth & Fyre sources and quotes Quest dehumidifiers on request and does not currently stock them, so this page is a buyer's guide to the lineup.
Quest's January 2025 catalog lists these units, rated at 80°F and 60 percent relative humidity, and describes them as using reclaimed, low GWP refrigerant.
Small veg and mother rooms often run on 120 volt circuits, which is where the Compact 100, 155 and 205 fit. Flower rooms in a commercial build usually step up to the 335 or 506 on 208 to 230 volt or 277 volt circuits, and large rooms with three phase service can use the 746.
The portable Hi-E Dry units suit dry rooms, temporary setups and backup capacity during a repair. Quest's earlier 506 could hang overhead on 3/8 inch threaded rod, which keeps floor space open between benches.
Size on the condition your room actually runs, not the headline rating. The current Quest 506 208/230V spec page lists 500 pints per day at 80°F and 60 percent relative humidity, but 320 pints per day at 75°F and 50 percent. A late flower room held near 75°F and 50 percent gets the lower figure.
Count the water you put in. Most irrigation water leaves the plants as transpiration, so the daily irrigation volume in a sealed room sets the moisture load. Divide that load by the unit's capacity at your setpoint and add a spare unit so one failure does not cost a crop.
Then add the dehumidifier's heat to your cooling load. Quest lists the 506 at 30,500 BTU total at rated conditions, of which 22,800 is heat of condensation and 7,700 is motor load. Our Cannabis HVAC Design Guide shows how to fold that into a room's cooling and airflow plan.
The closest comparison in our inventory is the Anden A710V3 grow optimized dehumidifier, which Urth & Fyre recently sold and can source again on request. On the two spec sheets, the Quest 506 (208/230V) removes 500 pints per day at 80°F and 60 percent at 9.2 pints per kWh, draws 9.9 amps at 230 volts, moves 1,150 CFM and weighs 275 lb.
The Anden A710V3 removes 710 pints per day at the same condition at 6.35 pints per kWh, runs on 277 volts at 17.4 amps, moves 1,760 CFM and weighs 360 lb. The Quest uses less power per pint, while one Anden covers more load per unit, so compare total units, circuits and hanging points for your room.
Quest's 746 is the step up for three phase rooms at 730 pints per day on 480 volts. For drying rooms or overflow, the portable Hi-E Dry units avoid a hard install.
Send us your room size, setpoints, irrigation volume and available voltage, and we will quote the Quest models that fit along with lead time. If you have Quest units you are retiring, list them through Sell Equipment.
To get started, request a Quest quote, or ask us to source an Anden A710V3.
Who makes Quest dehumidifiers?
Therma-Stor LLC makes Quest dehumidifiers and engineers and assembles them in Madison, Wisconsin. Therma-Stor was established in Madison in 1977 and lists Quest with its Santa Fe, Ultra-Aire and Phoenix brands. Therma-Stor is a sister company within Madison Industries, a privately held industrial group. Quest's own brochure dates the Quest brand to 2006.
How many pints per day does a Quest 506 remove?
The current Quest 506 208/230V removes 500 pints per day at 80°F and 60 percent relative humidity and 320 pints per day at 75°F and 50 percent, per Quest's spec page. The discontinued R410A version was rated at 506 pints per day at 80°F and 60 percent. Size on the lower figure if your flower room runs near 75°F.
What refrigerant do Quest dehumidifiers use?
Current Quest models such as the 506 208/230V (model 4046300) use R454B, and Quest's 2025 catalog describes the lineup as using reclaimed, low GWP refrigerant. Earlier units such as the discontinued 506 (model 4036600) and the Quest Dual 205 used R410A. Check the data plate on any used unit so your HVAC contractor brings the right refrigerant and tools.
Should I buy a Quest 506 or an Anden A710V3?
It depends on circuits and room load. The Quest 506 208/230V removes 500 pints per day at 9.2 pints per kWh on about 10 amps. The Anden A710V3 removes 710 pints per day at 6.35 pints per kWh on 17.4 amps at 277 volts. Compare total units, power and hanging points for your room before you choose.
What power does a Quest 506 need?
The current Quest 506 208/230V needs 208 to 230 volt single phase power and draws 9.9 amps at 230 volts or 10.9 amps at 208 volts, with a NEMA 6-20P plug. Quest also builds a separate 277 volt version of the 506. The larger Quest 746 runs on 480 volt, three phase service.
What warranty and listings do Quest dehumidifiers carry?
Quest lists a 5 year limited warranty on the current 506 and states that the unit is UL rated, ETL listed and compliant with California Title 24. Warranty claims, parts orders and product registration run through Quest's support site. On a used unit, ask the seller for the purchase date and registration record before relying on coverage.