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Quest

Quest builds commercial-grade refrigerant dehumidifiers for grow rooms, drying rooms, basements, crawl spaces, and water-damage restoration. Made by Therma-Stor in Madison, Wisconsin, the line-up spans entry units like the Quest 100 and Hi-E Dry 140 at 100 to 140 pints per day, mid-capacity workhorses including the Quest 155, Next-Gen 225, and Quest 335, and industrial systems such as the Quest 506 and Quest 746 that move up to 746 pints per day. Models run on 115V, 208 to 230V, 277V, and 480V three-phase, so the decision that matters most: matching pint-per-day capacity to room load and matching the unit voltage to the available circuit.

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Buyer's Guide

Quest: Complete Guide

How Do I Choose the Right Quest Dehumidifier?

Pick by pint-per-day capacity first, then voltage. Small sealed rooms and basements up to about 1,500 sq ft run well on the 100 to 155 pint class. Flowering rooms in the 1,500 to 3,000 sq ft range usually land on the Next-Gen 225 or the 335. Anything above that, or a multi-room facility, belongs on the 506 or 746. For the underlying physics of plant transpiration and room load see the pillar on humidity control fundamentals, and for the in-depth model walkthrough read our complete buying guide to Quest dehumidifiers.

Quest Dehumidifier Model Comparison

Model Capacity Voltage Best Use Mount
Quest 100 100 pints/day 115V 4x8 tents, small sealed rooms Stand or overhead hanging
Hi-E Dry 140 140 pints/day 115V Restoration, mobile drying, small grows Portable, wheeled
Quest 155 155 pints/day 208-230V 8x10 to 10x10 sealed flower rooms Ducted, hangable
Hi-E Dry 195 195 pints/day 115V Mobile commercial drying, multi-room restoration Portable, wheeled
Quest Next-Gen 225 225 pints/day 208-230V 10x10 to 12x16 sealed flower Ducted, hangable
Quest 335 335 pints/day 208-230V or 277V 15x20 commercial flower Ducted, fixed install
Quest 506 506 pints/day 208-230V or 277V 20x30 commercial flower, drying facility Ducted, fixed install
Quest 746 746 pints/day 480V 3-phase Multi-room facility, large commercial Ducted, fixed install

Capacity ratings are at AHAM conditions (80°F / 60% RH). Real-world grow-room throughput drops 10 to 20% in cooler dry rooms and rises slightly in hotter flower rooms.

Sizing Quest by Room Footprint

The simplest way to size is to match the dehumidifier to the room and to total lighting wattage. More light means more transpiration, which means more moisture load.

  • 4x4 to 4x8 tent or closet grow (under 600W): The Quest 100 on a standard 115V outlet handles this without overshooting. If the room ceiling is low, the Quest 100 hanging kit frees up floor space.
  • 8x10 to 10x10 sealed room (1 to 2 lights, 600 to 1,200W): The Quest 155 is the right size. It moves enough pints to keep up with peak irrigation and runs on the 208-230V service most sealed rooms already have.
  • 12x16 to 15x20 commercial flower (4 to 8 lights, 2,400 to 5,000W): The Next-Gen 225 or the Quest 335 depending on plant density. The 225 wins on pints-per-kWh efficiency; the 335 wins on absolute capacity for high-density rooms.
  • 20x30 dedicated flower or two-room facility (8+ lights): The Quest 506, sized to handle continuous duty with margin to spare. Step up to 277V if your service supports it for a smaller wire run.
  • Multi-room commercial cultivation or restoration: The Quest 746 on 480V three-phase, or run multiple 506 units with zoned ducting tied into an environmental controller.

Portable vs Ducted Quest Dehumidifiers

Quest splits the lineup into two install philosophies: portables that roll between rooms and ducted units that stay fixed.

  • Portables (Hi-E Dry 140, Hi-E Dry 195): Wheels, top handle, integrated condensate pump, and 115V plug. These are the right call for restoration crews, multi-room drying setups, or smaller grows where the unit needs to move. They run on a standard wall outlet, which simplifies the electrical plan.
  • Ducted, fixed install (Quest 155, 225, 335, 506, 746): Engineered for continuous duty inside a sealed flower or drying room. Return and supply plenums let you condition multiple zones from one unit. Voltage scales up with capacity, so larger models require dedicated 208-230V, 277V, or 480V service.
  • Quest 100: The exception. It is a single-zone 115V unit that runs on standard power but can be hung overhead with the Quest 100 hanging kit. Treat it as the smallest fixed install rather than a true portable.

Quest vs Anden vs Other Commercial Brands

Quest and Anden are both built by Therma-Stor in Wisconsin, so warranty paths, parts support, and build philosophy carry across the two lines. The split: Anden tends to lead on tight-fit ducted installs sized for boutique flower rooms (A70 through A210), while Quest covers the widest pint-per-day range from 100 up to 746 and dominates the commercial restoration market. For a head-to-head, see our Quest vs Anden Dehumidifiers review.

Buyers cross-shopping multiple manufacturers can browse the full commercial dehumidifiers category for side-by-side capacity comparisons with Ideal-Air, Cannadri, Dri-Eaz, and other high-capacity brands. For tent-sized applications, grow-tent dehumidifiers include the AC Infinity Hydrone and Ideal-Air alternatives that sit below the Quest 100.

Frequently Asked Questions

Are Quest dehumidifiers worth it?
For commercial grow rooms, drying rooms, and restoration work, yes. Quest uses MERV-rated filtration, ducted airflow, and refrigerant systems sized for continuous duty, which is what separates them from consumer dehumidifiers that fail under 24-hour cycling. The break-even point against cheaper portables shows up inside the first year on a full-time flowering room because Quest pulls more pints per kWh and rarely needs replacement.
Who makes Quest dehumidifiers?
Quest is built by Therma-Stor in Madison, Wisconsin. Therma-Stor also makes Anden, Phoenix, Santa Fe, and Ultra-Aire, so Quest shares an engineering and parts ecosystem with several of the other major commercial dehumidifier brands sold in the US.
What size Quest dehumidifier do I need for my grow room?
Use plant count and watts of lighting as the anchor. A 4x8 tent under 600W usually only needs the Quest 100. A sealed 10x10 flower room under 1,200W lands on the Quest 155 or Next-Gen 225. A 20x20 commercial flower room generally needs the Quest 335 or 506. Multi-room facilities almost always run the 746 or pair multiple 506 units.
How long do Quest dehumidifiers last?
Ten years of continuous-duty service is typical when the air filter is replaced on schedule and the unit is kept inside its rated operating envelope (around 33F to 100F ambient). Therma-Stor backs the line with a 6-year warranty on the sealed refrigeration system and 1 year on parts and labor, which is longer than most consumer-grade units carry.
Are Quest and Anden the same?
Same parent company, different product lines. Both are made by Therma-Stor, which means warranty support and dealer networks overlap. Quest covers a wider capacity range, from 100 to 746 pints per day, while Anden focuses on tightly ducted units sized for sealed flower rooms. If you already run an Anden A95 or A100 and want to scale up past 200 pints, Quest is the natural step. Full breakdown: Quest vs Anden Dehumidifiers.
Do Quest dehumidifiers work in cold rooms?
Quest units operate down to about 33F ambient, which covers most drying rooms but not freezer or cold-storage applications. Performance drops as temperature falls because refrigerant dehumidifiers rely on a warm coil for condensation. For curing rooms held in the 50F to 65F range, Quest holds its rated pints-per-day. Below that, capacity falls off sharply. For dry-room sizing specifically, see our drying-room dehumidifier guide.
Does Quest make portable dehumidifiers?
Yes. The Quest Hi-E Dry 140 and Hi-E Dry 195 are the wheeled portables in the lineup, sized for restoration crews and small-to-mid grow operations that need to move the unit between rooms. The Quest 100 hangs from a ceiling using the 100 hanging kit. Everything from the 155 up is engineered for fixed install with ducted return and supply.
What is the most efficient Quest dehumidifier?
The Quest Next-Gen 225 leads the residential-voltage line on pints per kWh thanks to its redesigned chassis and updated refrigerant circuit. For larger commercial rooms the Quest 506 holds the top efficiency spot in the 208 to 230V class. The 746 is the highest absolute capacity but trades some efficiency for the three-phase power and continuous-duty design. For a deeper Quest 225 walkthrough, read our Quest 225 Dehumidifier Review.

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