Best Dehumidifiers for Grow Rooms & How To Calculate Dehumidification Needs
What to Consider When Purchasing a Dehumidifier for Grow Rooms and Hydroponic Facilities
Selecting the right dehumidifier for a hydroponic or soil-based grow room is one of the most impactful decisions you can make for crop health, disease prevention, and stable yields. With so many brands, capacities, and technologies on the market, it can be difficult to determine which grow room dehumidifier will actually match your crop load and environmental setpoints.
To simplify the selection process, it helps to focus on seven vital dehumidifier parameters. Once you understand these seven points and how they relate to crop transpiration rate and room conditions, choosing a commercial grow room dehumidifier becomes less guesswork and more applied science.
7 Vital Dehumidifier Parameters for Ideal Model Selection
1. Pints Per Day (PPD): Sizing Your Dehumidifier to Crop Load
The single most important parameter for any grow room dehumidifier is its moisture removal rate, usually expressed as pints per day (PPD). This value indicates how much water the unit can pull from the air over 24 hours under its rated test conditions.
In a controlled grow room, nearly all irrigation water that is not stored in plant biomass or drained away will eventually enter the air as water vapor. That means your dehumidifier capacity must closely match total daily plant transpiration plus evaporation from any open-water surfaces such as reservoirs, trays, and sumps.
The higher the PPD rating, the larger the facility and canopy load that the grow room dehumidifier can support while still maintaining stable relative humidity.
Estimating Required Pints Per Day from Crop Count
You can estimate the required grow room dehumidifier capacity in PPD using a simple, crop-based relationship:
(Number of crops) × (daily water use per crop in pints) = required dehumidifier PPD
This turns dehumidifier sizing for hydroponic growers from a rough guess into a calculation based on real irrigation volumes and total plant count.
Pints Per Day Calculation Example
(100 crops) × (8 pints per day per crop) = 800 PPD dehumidifier required
In this example, a model such as the Quest Dehumidifier 876 Pint (220–240 V) would comfortably handle the moisture load, with extra capacity available to absorb environmental spikes or slightly higher plant uptake. For a commercial or high-density grow room, that margin is often what keeps RH% in the target range instead of drifting into disease risk.
2. BTUs: Heat Energy and Power Relationship
BTU (British Thermal Unit) is a measure of heat energy. One BTU is the amount of energy required to raise one pound of water by 1 °F in temperature.
When we divide BTU by time, we get a measure of power:
BTU/hr = unit of thermal power
Dehumidifier specification sheets often list BTU or BTU/hr alongside electrical power in watts or amps. These are simply different ways of describing how much energy the unit consumes and rejects into the grow room as heat. Understanding this helps you integrate dehumidification with cooling when designing a complete grow room HVAC strategy.
Key Energy Conversions
1 BTU/hr ≈ 0.293 W ≈ 3.93 × 10-4 horsepower ≈ 1055 J/hr
On dehumidifier spec sheets, electrical ratings are usually given as watts (W) or amps (A). These values represent the total power draw required to operate the unit and remove moisture, which becomes a key piece of data when you are planning electrical infrastructure for a commercial grow room dehumidifier layout.
3. Power Use: Watts and Amps
You can convert between watts and amps using basic electrical relationships:
Watts (W) = Amps (A) × Voltage (V)
Amps (A) = Watts (W) ÷ Voltage (V)
These equations are essential when designing electrical layouts, choosing breaker sizes, and calculating total load in a commercial grow room or when integrating dehumidification with an HVAC system. Oversizing circuits or underestimating combined load can both create costly headaches, so it pays to run the numbers early.
4. Dehumidifier Energy Efficiency (Pints/kWh)
Every grow room dehumidifier releases some of its input energy as heat while removing moisture from the air. High-quality components and well-designed refrigeration circuits convert more of that electrical energy into effective water removal, which lowers operating cost over the life of the equipment.
Because moisture removal (PPD) is the critical function in a grow room dehumidifier, efficiency is best expressed as:
Efficiency = pints removed per kilowatt-hour (pints/kWh)
Mathematically:
(Pints per hour) ÷ (kW) = pints/kWh
Efficiency Calculation Example (Quest 506-Pint Model)
For the Quest Dehumidifier 506-Pint model:
[(506 pints/day) ÷ (24 h/day)] ÷ (2.7 kW) = 7.81 pints/kWh
An efficiency of 7.81 pints/kWh is considered very strong in a commercial grow environment, especially when units run many hours per day over the full crop cycle. For hydroponic growers, this directly affects operating expenses and long-term return on investment for each grow room dehumidifier.
5. Facility Scale: Matching Dehumidifiers to Grow Room Size
Beyond raw PPD, it is useful to think about dehumidifier selection in terms of grow area (square feet) and facility type. The following breakdown is commonly used for hydroponic and controlled-environment facilities to match the scale of the grow room dehumidifier to the production footprint.
Large-Scale Commercial Facilities
Definition: total grow area ≥ 2,000 ft².
At this scale, dehumidification is usually centralized and integrated into a full environmental control strategy. Dehumidifier brands frequently used for large commercial spaces include:
Mounted, high-capacity units are typically preferred because crop production schedules are consistent and rooms are in continuous use, making a robust commercial grow room dehumidifier system essential.
Small-Scale Commercial Facilities
Definition: total grow area between 500–1,999 ft².
Brands suitable for this scale include:
These sites often have multiple flower rooms, veg rooms, and dry/cure rooms. Mounted grow room dehumidifiers are generally recommended for reliable, repeatable humidity control and easier integration with ducting and other air-handling equipment.
Small Business Grow Rooms
Definition: total grow area between 100–499 ft².
Dehumidifier brands commonly used at this size include:
Quest | Ideal Air | Dri-Eaz | Active Air | Surna | Aura Systems
These facilities are often fully indoors, so hybrid conditioning strategies—cooling plus dehumidification plus circulation—are very effective. At the upper end of this range (over ~400 ft²), Surna’s indoor-engineered units become especially appropriate because they are designed specifically for precision environmental and humidity control in grow rooms.
Tiny Business & Hobby Grow Rooms
Definition: total grow area between 0–99 ft² (closets, small tents, micro-grows, and personal gardens).
Common brands in this category include:
Quest | Ideal Air | Dri-Eaz | Active Air | Integra Boost
At this scale, a portable dehumidifier for grow rooms is usually preferred because crop mixes change frequently, equipment is moved often, and the grower may repurpose units for drying or curing harvested product.
6. Dehumidifier Style: Portable vs Mounted
Portable Dehumidifiers
Many dehumidifiers designed for small grow rooms are built with caster wheels and grab handles, making it easy to position them wherever humidity is highest. This flexibility is especially useful when rotating equipment between veg, flower, and dry/cure spaces or between multiple hobby grow tents.
Portable dehumidifier brands include:
Quest | Dri-Eaz | Ideal Air | Active Air | Aura Systems
Mounted Dehumidifiers
Commercial-scale grow room dehumidifiers are usually larger and heavier and are often designed to be mounted to ceilings, floors, or shelves. These units can be ducted to condition multiple rooms from a central location and are typically integrated into the overall airflow and HVAC design.
Mounted dehumidifier brands include:
Quest | Dri-Eaz | SubCooled | Surna
Mounting Accessory Options
Overhead mounting: the dehumidifier is suspended from the ceiling using brackets or frames. This keeps equipment off the floor, improves airflow distribution, and helps maintain ideal intake and discharge positions.
Roof mount: equipment is mounted directly on or into the roof structure of the facility. This can be done from above the roof or within the grow space, depending on structural constraints and service-access requirements.
7. Eco-Friendly Features and Warranty Considerations
Eco-Friendly Dehumidifier Features
Many modern grow room dehumidifier lines now integrate eco-focused features that conserve both energy and water, including high-efficiency refrigeration circuits and condensate collection or recycling. Where regulations allow, condensate can often be captured and repurposed, reducing fresh water demand in hydroponic systems.
Brands that offer eco-friendly features include:
Quest | Dri-Eaz | Active Air | Surna
Warranty Ranges and What They Cover
A dehumidifier warranty defines the guaranteed service life of the equipment, assuming proper installation and standard operating conditions. Overall warranty coverage can vary significantly between manufacturers—from roughly one year up to six years—depending on the component.
More robust brands, such as Quest, typically offer:
5–6 year coverage on the compressor and refrigerant system
Across most major dehumidifier brands, it is common to see:
1-year warranty for labor and other parts
For growers, strong compressor and refrigerant warranties are particularly important because these are some of the most expensive components to replace and they are central to long-term performance of any grow room dehumidifier.
Overview of GrowersHouse Dehumidifier Brands
GrowersHouse offers multiple dehumidifier brands to cover a broad range of commercial and small-scale cultivation spaces, from indoor hydroponic grow rooms to greenhouse environments. Each brand has distinct strengths depending on room size, budget, and how tightly you need to control humidity.
The sections below summarize eight dehumidifier brands in order of how many models are available per brand, from highest to lowest.
Quest Dehumidifiers
Quest is a top-tier grow room dehumidifier brand with over 20 models ranging from compact units to large commercial systems. All models are engineered for high efficiency and long service life in demanding cultivation environments.
Quest units use a patented refrigeration system designed to withstand heavy use, paired with long-life impeller fans for durability. They feature robust air filtration and environmentally conscious R410A refrigerant. Many models include low-voltage control options for seamless integration with a variety of environmental controllers.
The Quest 70 Pint Per Day model is a mountable unit that can be installed on multiple surfaces or suspended using mounting accessories. It is a highly efficient hydroponic dehumidifier for small grow rooms, with each unit able to dehumidify roughly 75 ft² of crop area, depending on plant density and irrigation rates.
The Quest 506 Commercial 500 Pint Per Day dehumidifier is a commercial-scale, mountable model that can use ducting to service multiple rooms. It is well suited to large indoor grow facilities, with each unit typically supporting around 550 ft² of canopy area.
For portable applications, the Quest CDG174 Dehumidifier is one of the highest-efficiency portable dehumidifiers at GrowersHouse, capable of dehumidifying approximately 200 ft² of crop area. It is a strong option for flexible spaces, temporary setups, or dedicated drying rooms.
Ideal Air Dehumidifiers
Ideal Air dehumidifiers offer compact, streamlined, portable solutions at a lower price point than some premium commercial brands while remaining effective for small grow rooms and curing spaces.
The Ideal Air 30–50 Pint Per Day dehumidifier is a portable unit suitable for very small grow operations, including backyard or personal gardens. It can handle roughly 30 ft² of crop area under moderate conditions and is also effective for drying and curing harvested material.
Ideal Air units meet AHAM standards and are well suited for small grow rooms or dry/cure spaces requiring between 30–180 PPD of moisture removal. They offer quick relative humidity control with easy-access, washable filters and removable water tanks.
SubCooled Dehumidifiers
SubCooled systems are engineered as large-scale, commercial grow room dehumidifiers for the biggest cultivation facilities with very high moisture loads.
SubCooled models can remove between approximately 705–3000 pints per day, making them ideal for facilities larger than 1,000 ft². A single 3000 PPD SubCooled dehumidifier can support a grow area of up to about 3,375 ft², depending on crop type and watering intensity.
Each unit features an all-steel, commercial-grade build with humidistat-controlled cooling and heating. Units can be mounted on ceilings, floors, or shelves and are designed to be technician-friendly for easier maintenance. SubCooled systems are manufactured in the USA and commonly carry a one-year limited warranty on defective parts.
The SubCooled Air Grow 30 Dehumidifier – 3000 PPD (15-ton) air conditioner is the largest dehumidifier offered at GrowersHouse and is well matched to the largest commercial cultivation facilities, capable of dehumidifying around 3,300 ft² per unit.
Active Air Dehumidifiers
Active Air provides small-scale, portable dehumidifiers that typically remove between 60–190 PPD. These are ideal for smaller cultivation spaces or for use in harvested product drying and curing rooms.
Active Air units are designed for performance and reliability, with precise digital controls, robust metal housings, and powerful compressors. Filters are removable for easy cleaning.
The Active Air Dehumidifier 190 Pint Per Day model is a portable unit ideally suited for flexible grow environments of around 210 ft², making it a solid match for small flower rooms, veg tents, or dedicated curing spaces.
Surna Dehumidifiers
Surna focuses on dehumidifiers engineered specifically for commercial indoor cultivation. Their systems are designed to provide fine-grain control of environmental variables, which is particularly useful for research grows and tightly dialed hydroponic systems.
The Surna 250 PPD Dehumidifier (Air Cooled, 2-Ton) is a 250 PPD unit suited to indoor grow environments, with each unit supporting an estimated 275 ft² of crop production. This model features commercial-grade construction and components, plus a long list of advanced features.
Surna dehumidifiers perform best between 75–85 °F. They include water reclamation dehumidification to reduce water use, as well as a remote dehumidistat for full control from almost anywhere. The systems are highly engineered yet plug-and-play, making them straightforward to integrate into existing grow room humidity control strategies.
Aura Systems Dehumidifiers
Aura Systems offers smaller-scale, portable dehumidifiers with capacities around 180 PPD. These units are more suitable for small cultivation spaces or curing rooms rather than very large commercial environments.
The Aura Systems 180 Pint Portable Dehumidifier includes auto-restart, control-ready features, an easy-to-use digital display (showing both humidity and temperature), and a removable, washable filter. Powder-coated metal casings improve durability. Rolling caster wheels make these units easier to move than many other portable grow room dehumidifiers, and they are typically well matched to grow spaces of around 200 ft².
Integra Boost Desiccant Solutions
Integra Boost is not a powered dehumidifier but a desiccant-based drying and curing solution, ideal for small-scale or home growers.
The Integra Boost 5-Gallon Bucket with 30 Desiccant Packs is designed for curing harvested plant material. The packs help protect against pathogens such as fungi while greatly accelerating the drying period and contributing to a more uniform final moisture content throughout the product.
Each desiccant pack can absorb up to 158% of its weight over 50+ days and, in total, can be used to store and dry up to approximately 4 lbs of plant material. This makes it a simple, low-cost option for small-scale growers who want more consistent curing without investing in additional powered dehumidification.
After Selection: Using Your Dehumidifier with Environmental Data
Once you have selected the appropriate dehumidifier size and brand for your grow room, the next step is to operate it based on real environmental data rather than intuition. That means understanding basic controlled-environment terminology and using psychrometrics to interpret temperature and humidity measurements in terms of actual moisture content in the air.
Basic Controlled Environment Terminology
| Environment | Temperature | Humidity | Relative Humidity (%) |
|---|---|---|---|
|
The environment includes all of the air surrounding the crops within the grow room. For growers, this is the air volume in which plants transpire, lights heat the space, and conditioning equipment operates. By combining temperature and relative humidity, we can use a psychrometric chart to determine key parameters related to the moisture content of the air around the canopy. The mixture of air and suspended water vapor in a grow facility is known as the gas–vapor mixture. |
The air temperature in the grow room strongly influences how much moisture it can hold. Warmer air can hold more water vapor; cooler air can hold less. Higher temperatures → higher moisture capacity Temperature swings can cause dramatic shifts in relative humidity. At night, when temperature drops, RH% rises; in the morning, as temperature increases, RH% falls. |
Humidity describes the moisture content of the air surrounding the crops. Higher humidity means a higher concentration of water in the air. Humidity can be defined in three ways: Specific humidity | Absolute humidity | Relative humidity The first two definitions involve mass ratios of water vapor to dry air. Relative humidity, however, is easier to measure continuously with digital sensors, which is why growers rely on it most often. |
Relative humidity (RH%) is expressed as a percentage of the maximum amount of moisture the air can hold at a particular temperature before condensation occurs. More precisely, RH% is the ratio of the actual vapor pressure of moisture in a sample of air to the saturation vapor pressure of that same sample at the dry-bulb temperature. |
Using Psychrometrics to Optimize Dehumidification
What Is Psychrometrics?
Psychrometrics is the field of engineering that deals with the physical and thermodynamic properties of gas–vapor mixtures—exactly what we are dealing with in a grow room full of warm, moist air.
With just temperature and RH%, a psychrometric chart allows you to calculate several important parameters describing the air in your grow environment and how much moisture your dehumidifier needs to remove.
A standard psychrometric chart can provide any of these seven parameters as long as you know at least two of them (the underlined are typically measured directly):
Measuring Temperature and RH% in the Grow Room
To use a psychrometric chart effectively, you must measure temperature and RH% with electronic sensors. A high-quality combination probe (temperature + RH) is ideal, especially for commercial facilities where accuracy, longevity, and durability are critical.
The probe should be shaded from direct sun or artificial light and located where there is continuous air movement of roughly 1 m/s. Poor probe placement is one of the easiest ways to generate misleading environmental data.
Two major factors that can distort sensor readings are:
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Radiation: direct light or radiant heat warms the probe, causing the measured temperature to read higher than actual and the RH% to read lower.
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Stale air: if the probe sits in a dead zone with poor airflow, it samples a very small volume of air that may not be representative of the room as a whole.
Building a Probe Shielding Module
A simple way to reduce both radiation and stale-air issues is to enclose the sensing probe in a small “probe shielding module” with shade and forced airflow. One DIY approach uses:
6" L × 3" D PVC pipe with cap (modified to hold the probe) + 3" D computer fan
The PVC body shields the probe from light, while the fan pulls air across the sensor at a controlled speed. This provides more accurate and stable readings that you can trust when sizing and operating your grow room dehumidifier or tuning humidity setpoints.
Wet-Bulb and Dry-Bulb Temperatures
Wet-Bulb Temperature
Wet-bulb temperature is the temperature that air would reach if water were allowed to evaporate into it until saturation (100% RH%) is achieved at constant pressure. It is commonly measured by wrapping a wet cloth around a thermometer and moving air rapidly across it.
Key relationships:
When RH% = 100%, wet-bulb temperature = dry-bulb temperature.
When RH% < 100%, wet-bulb temperature < dry-bulb temperature.
Dry-Bulb Temperature
Dry-bulb temperature is simply the temperature indicated by a thermometer exposed to air that is shaded from direct solar or lamp radiation. In practice, this is what growers usually mean by “room temperature” and it is the standard temperature used alongside RH% on psychrometric charts.
Dew Point and Its Role in Grow Rooms
Dew Point Temperature
Dew point is the temperature at which the water vapor in air begins to condense into liquid at a constant pressure. It is effectively the saturation temperature of the moisture present in the air.
On plants, dew point conditions are met when the leaf or bud surface temperature reaches the dew point. At that point, condensation forms on plant surfaces—a situation that can drastically increase disease risk in dense canopies, even if the grow room dehumidifier is sized correctly.
Dew Point vs Wet-Bulb Temperature
Both dew point and wet-bulb temperature are related to moisture content, but they are not measured the same way:
- Dew point: the actual temperature required for air to reach 100% saturation (condensation begins).
- Wet bulb: the temperature after evaporative cooling of a wet surface exposed to a strong air current.
In grow room design, dew point is generally more useful for determining how far you can cool the air using evaporative methods (such as high-pressure fogging or wet pads) before hitting condensation and disease risk on plant surfaces.
Humidity Ratio and Specific Volume
Humidity Ratio (Moisture Content)
Humidity ratio is the mass of moisture per unit mass of dry air. On a psychrometric chart, it is usually expressed in kilograms of moisture per kilogram of dry air, ranging from 0 (absolutely dry air) up to around 0.03 kg/kg for fully saturated air.
As relative humidity increases at a given temperature, the humidity ratio increases as well, meaning the total mass of water in the air is higher. This is exactly what your grow room dehumidifier must remove over time.
Specific Volume
Specific volume quantifies the total volume of both dry air and water vapor per unit mass of dry air. In other words, it describes how much space a kilogram (or pound) of the air–vapor mixture occupies.
The concept is similar to humidity ratio, but based on volume rather than mass. For dehumidifier sizing, specific volume is especially useful because all grow room dehumidifiers are working on a certain volume of air per unit time, and their performance is rated by PPD moisture removal.
For example, at a temperature of 75 °F and RH% = 60%, the specific volume might be around 14 ft³/lb. This helps translate square footage and ceiling height into the actual air volume that your dehumidifier is conditioning.
Specific Enthalpy and Energy in the Grow Room
Specific enthalpy represents the total energy content of both the dry air and water vapor per unit mass of dry air, typically expressed in kilojoules per kilogram. In a grow room, it reflects how much heat energy is stored in the air–vapor mixture.
While enthalpy is not usually the primary variable for choosing a dehumidifier model, it does provide insight into how much energy the unit must move or remove to achieve a target condition. That, in turn, connects directly to real-world power consumption for your grow room dehumidifier.
Water has a very high specific heat, meaning it can absorb large amounts of energy with only small changes in temperature. This is why strategies such as evaporative cooling (misting, fogging, wet pads) can be so effective at reducing air temperature in a grow room: as water vapor absorbs energy during evaporation, air temperature drops while RH% increases.
Key Takeaways for Hydroponic Growers
When you view dehumidifier selection and operation through the lens of psychrometrics and real crop water use, humidity control stops being a guessing game. By focusing on:
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Accurate estimation of plant transpiration and irrigation (to determine PPD)
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Correct facility scale (ft²) and total air volume
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Dehumidifier efficiency in pints/kWh over the full crop cycle
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Smart placement of sensors and strong, uniform airflow around the canopy
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Matching portable or mounted dehumidifier styles to room layout and workflow
you can choose and operate a grow room dehumidifier that reliably protects plant health, reduces disease pressure, and stabilizes yields across successive harvests.