Best Dehumidifiers for Grow Rooms & How To Calculate Dehumidification Needs

Dehumidifier for Grow Rooms


The (7) Vital Dehumifier Parameters for Ideal Model Selection  +  Using Psychrometrics to Determine Moisture Content Parameters of the Air in a Grow Environment

IMAGE ABOVE (#1): Images of the (4) Most Popular Dehumidifer Brands  Shown in Order from Greatest to Least Powerful in terms of Moisture Removal (Pints Per Day | PpD) (Left to Right)

SubCooled (3000 PpD) | Quest (500 PpD) | Ideal Air (180 PpD) | Dri-Eaz (60 PpD)  

A large assortment of different dehumidifier based brands made avaliable at a variety of scales as well as with varying capabilities makes selecting the correct model for a particular crop cultivation facility and production plan difficult.

To simplify the dehumidifier selection process we have created an effective stratedgy that focuses on just (7) Vital Dehimidifier Parameters that, when used properly, makes the purchase of these complicated, yetcritical, products for maintaining the ideal facility environment almost stress-free!



A Dehumidifier’s Most Important Parameter is the Magnitude of it's Moisture Removal Rate.

The Greater the (Pints Per Day) Removed by the Dehumidifier the Larger the Facility & (#) of Crops that can be Housed.

Estimating the Required Moisture Removal Rate in (Pints Per Day) is Accomplished with the Equation Below Using Crop Capacity and Watering Rate:

(# Crops)  *  (Daily Water Rate Per Crop)  =  (Dehumidifer's Pints Per Day Water Removal)


(100 Crops)  *  (8 Pints Per Day)  =  (800 Pint Per Day) Dehumidifer

BEST DEHUMIDIFIER OPTION | "Quest Dehumidifier 876 Pint" (220-240 V)


British Thermal Unit is a measurement of thermal (heat) energy where each unit is the amount of energy it takes to raise (1) pound of water (1) degree Fahrenheit in temperature.

Unit of Power is Calculated by Dividing BTU by Time  (BTUs/hr)


(1) BTU/hr  =  (0.293) Watt  =  (3.93 x 10-4) Horsepower  =  (1055) Joules/hr

Expressed in terms of (Watts) or (Amps) on dehumidifier specifications and is a Measurement of the Total Power Required to Make the Product Function and remove moisture.

Calculate for Either (Watts) or (Amps) by Using the Equations Below:


(Watts)  =  (Amps)  *  (Voltage)

- OR -

(Amps)  =  (Watts)  /  (Voltage)


Every Dehumidifier Dissipates at Least Some of the Energy used to power the removal of moisture from the air. This energy usually Dissipates from the Dehumidifers in the Form of Heat.

However, top of the line electrical components have the ability to use the power provided more efficiently thereby reducing the cost of running over time. 

Since the (Pints Per Day) Moisture Removal Rate is the Critical Function of a Dehumidifier the Efficiency can be Expressed in the Following Terms  -  (Pints/kWh)


(Pints Per Hour)  /  (Kilo-Watts)  =  (Pints/kWh)


"Quest Dehumidifier (506-Pint) Model"

[(506 Pints/Day) / (24 Hrs/Day)] / (2.7 kW)  =  (7.81)(Pints/kWh)


There are (2) Scales of Commercial Facility:

Large Scale Commercial Facility: Defined as having a Total Grow Area  =  (2,000 ft2) or More

Dehumidifier Brands Include:


Small Scale Commercial Facility: Defined as having a Total Grow Area  =  (500 – 1,999 ft2).  

Dehumidifier Brands Include:

Quest | SubCooled

Commercial facilities generally have multiple rooms to condition. A Mounted Dehumidifier is Generally Recommended for Commercial Facilities since crop production is more consistent over time.


Defined as having a Total Grow Area  =  (100 - 499 ft2)  

Dehumidifer Brands Incude:

Quest | Ideal Air | Dri-Eaz | Active Air | Surna | Aura Systems

Generally Located Indoors at this scale which makes the Surna Particularly Effective as it's Designed for Indoor Use, however it's size makes it more ideal for Facilities Over (400 ft2)


This Category Includes Only the Smallest of Crop Production Facilities with a Total Grow Area  =  (0 – 99 ft2)

Dehumidifer Brands Include:

Quest | Ideal Air | Dri-Eaz | Active Air | Integra Boost

Portable Dehumidifiers are Preferential in this case since small scale facilities grow the greatest variety of crops and undergo change regualrly.


Many of the brands with dehumidifiers build for small scale grow rooms have wheels which make them very easy to transport. Particularly useful if you need to move the dehumidifier often.

Portable Dehumidifer Brands Include:

Quest | Dri-Eaz | Ideal Air | Active Air | Aura Systems


The brands that have dehumidifiers build for commercial scale crop production are generally not portable because of their large size and heavy weight. These dehumidifiers can be mounted to the ceiling, floor or shelf and often supply multiple grow rooms with conditioned air.

Mounted Dehumidifier Brands Include:

Quest | Dri-Eaz | SubCooled | Surna


A type of mounting where the dehumidifier is installed by hanging it from the ceiling. This can be used to ensure the dehumidifier is Mounted in an Ideal Position for Both Installation and Air Conditioning purposes.


Equipment used to mount a dehumidifier directly to the ceiling of the facility. The dehumidifier can be mounted on top of the roof or from within the grow facility itself.


Many dehumidifier brands include eco-friendly features to Conserve Energy & Water Including Highly Efficient Refrigerant Systems and Condensate Recycling.

Brands that Include an Eco-Friendly Feature Include:

Quest | Dri-Eaz | Active Air | Surna

A guaranteed life-span of a specific dehumidifier where the product is replaced at no extra charge to the customer assuming not fault on their part.

Overall the Warrenty alloted to the dehumidifers varies sigificantly from (1-Yr) to (6-Yrs)

Warrenty also Varies between Parts Utilized by the Dehumidifiers with the more competant brands like Quest & Dri-Eaz providing:

(5-Yrs) & (6-Yrs) Warrenty Protection for the Compressor & Refigerant Systems

All Dehumidifer Brands provide:

(1-Yr) Warrenty for Labor & Other Parts

GrowersHouse provides several different brands of dehumidifer to cover a broad range of commerical and small scale crop cultivation facilities with both indoor or greenhouse based environments; as such each brand provides growers with it's own set of advantages and disadvantages. 

Below is a Table of All GrowersHouse's Dehumidifier Brands with Each Tab Containing Detailed Information on the Brand Highlighted; the table is labeled in order of total number of avaliable models per brand with the highest first (Quest) and lowest last (Integra-Boost)

GROWERSHOUSE (8) DEHUMIDIFER                              BRANDS

IMAGE BELOW"Quest 70 Pint Per Day" Dehumidifier Model. Mountable on mutiple surfaces or by hanging with the addition of specific Mounting Accesories. Most efficient dehumidifier option for small scale grow rooms with each unit able to dehumidify around (75 ft2) crop area. 

Consider GrowersHouse’s top of the line brand for high capacity dehumidification with the greatest results as well as actual lab tested proof that the system has the ability to maintain a very high efficiency over time for both small scale and commercial scale crop production that requires between (70 – 876) pints per day moisture removal. Both mountable and portable option are avalaible with a variety of avaliable accesories.

With over (20) individual Dehumidifier models Quest is GrowersHouse's number one dehumidifer based product. Every model maintains industry leading efficiency thanks to the specially patented refrigeration system built to withstand heavy use with a long-life impeller fan installed for added durability.

Superior air filtration that’s more environmentally friendly because the units utilize R410A rated refrigerant. Low voltage control mean units can be powered by a greater variety of power inputs. 

IMAGE ABOVE: "Quest 506 Commerical 500 Pint Per Day" Dehumidifer Model. Mountable on mutiple surfaces or by hanging with the addition of specific Mounting Accesories. Can utilize ducting to supply multiple grow rooms and is ideal choice for commerical crop cultivation with each unit able to dehumidify around (550 ft2) each. 

IMAGE ABOVE: "Quest CDG174 Dehumidifier" Model which is the Highest Efficiency Portable Dehumidifer at GrowersHouse. Can dehumidify around (200 ft2) of crop production area. 

BELOW IMAGE: The "Dri-Eaz "LGR 7000XLi Dehumidifier - (130 pints/day)is a Portable Dehumidifier Ideally Suited for the Flexible Cultivation of Crops within an Area Around (140 ft2) Per Unit

Compact & Portable Dehumidifiers Ideal for Smaller Grow Rooms that Require up to (64 – 170) Pints Per Day Moisture Removal Rate

Delivers growers better information than other dehumidifiers with inlet and outlet temperature, relative humidity and built in humidistats all portrayed on an LED screen. The refrigerant system and components are well engineered and highly efficient as well as durable.

Several different varieties of dehumidifer exsist within the Dri-Eaz brand that vary in complexity and avaliability of features making it a great brand to choose from for smaller scale growers. 

Includes a Lifetime Warranty on Housing and (6-Years) for the Refrigeration System Providing Assurances of the Dehumidifier's High Reliability & Durability.

This Brand has the Best Warrenty Avaliable Out of All Other Dehumidifiers!

ABOVE IMAGE: The Dri-Eaz "Enviroboss EB140 (80 Pint Per Day) Commercial Dehumidifier" is a Compact Moutable Unit that is Ideally Suited for Small, Consistent, Crop Production Spaces Around (87.5 ft2) Per Unit

IMAGE BELOW: "Ideal-Air 30-50 Pint Per Day" Dehumidifier Model. Portable option for very small scale grow opteration, even backyard or personal gardening based with the ability to dehumidify around (30 ft2) of crop prodution area. Also well suited for drying or curing harvested crop product. 

Highly compact, streamline and portable the ideal-air dehumidifiers are perfect for those that want to utilize a cheaper alternative to the more expensive dehumidifier brands but still maintains highly effective.

Meets all AHAM standards and is Ideally suited for small scale grows or curing rooms that require (30 – 180) pints per day moisture removal.

Relative Humidity quick maintenance with easy filter access, which is also washable, as well as a removable from the water tank of the dehumidifier.

Best Application is Acting as a Large Commercial Scale Dehumidifier for the biggest of crop production facilities with up to (705 – 3000) pints per day.

The Best Choice for Crop Production Facilities Larger than (1000 ft2). A Single One of the (3000 Pint Per Day) Dehumidifiers can Support a Grow Area Up To (3,375 ft2)

Every Model has an all steel commercial grade build with humidistat controlled cooling and heating that can be mounted on ceilings, floors or shelves. HVAC technician friendly for easier maintenance. Made in the USA.

One year limited warranty on any defective parts.

ABOVE IMAGE: The Subcooled "Air Grow 30 Dehumidifier - (3000 pints per day) (15-ton) air conditioner" is the Largest Dehumidifier Offered at GrowersHouse and is Ideally Suited for the Largest Scale Commerical Cultivation Facilities with the Ability to Dehumdify Around (3,300 ft2) Per Unit.

Small scale, portable, dehumidifiers that can remove between (60) -or- (190) pints per day and is ideal for smaller scale crop production facilities or harvested product curing. 

Provides high performance, reliability and precise digital control. Built heavy duty to last with coated metal casing and powerful compressors. Removable filter for easy cleaning.

IMAGE ABOVE: The "Active-Air Dehumidifier, (190 Pint Per Day)" is a Portable Unit Ideally Suited for Flexible Crop Production Facilites Around (210 ft2)

The "Surna 250 PPD Dehumidifer" is an air cooled (2) ton – (250) pints per day dehumidifier that is ideally suited and finely engineered for commerical indoor crop cultivation with Each Unit Suppporting an Estimated (275 ft2) of Crop Production.

Commercial grade construction & components in combination with a long list of features makes the Surna Dehumidifier the best option for growers who want the most control over their grow environment (particularly useful for cultivation based research).

Most efficient when utilized between the temperatures (75 – 85 F). System includes water reclamation dehumidification which saves on water use as well as a remote dehimidistat for complete control from anywhere. Intelligent and highly engineered design that’s plug and play.

IMAGE ABOVE: The "Surna 250 PPD Dehumidifier Air Cooled 2 Ton - (250 Pints Per Day)is a Mountable, High Efficiency Unit, Ideally Suited for Indoor Grow Environments Cultivating Around (275 ft2) of Crops. 

Smaller scale, portable, dehumidifier with (180) pint per day moisture removal rate that's more ideally suited for small scale crop cultivation or harvested product curing.

Auto-restart that’s control ready. Easy to use digital display with temperature and humidity readings. Removable and washable filter for easy cleaning. Powder-coated metal casing for long life. Easier to move than other portable dehumidifiers with rolling caster molded wheels.

ABOVE IMAGE: The "Aura Systems 180 Pint Portable Dehumidifier" is a Portable Dehumidifier Ideally Suited for Grow Environments Around (200 ft2)

Pack of (30) Dehumidifer Dessicant Packs with 5-gallon bucket ideally suited for drying and curing harvested product. Keeps pathogens, like fungus, from infecting the plant material being cured as well as greatly accelerates the drying period resulting in a harvested product that has a greater final moisture consistancy throughout.

Dessicant packs can bsorb up to (158%) of their weight over the course of (50) or more days and can store + dry up to (4 LBS) of plant material

ABOVE IMAGE: The "Integra Boost 5 Gallon Bucket with 30 Desiccant Packs Curing Solution" is a Great Inexpensive Alternative for Curing Crops Harvested from Small Scale or Backyard Based Cultivation. 

After making the ideal dehumidifier model selection it's time to begin using your dehumidifier to the greatest advantage of the crops being cultivated possible by taking steps to ensure you understand the important parameters that influence the dehumidifier including:

Basic Controlled Environmental Terminology  +  Psychrometrics


Includes All the Air Available to the Crops being Cultivated within a Grow Room.

To understand more complex environmental values Temperature and Relative Humidity can be Apllied to a Psychrometrics Chart, to Determine Important Parameters Related to the Moisture Content of the Air surrounding the crops being produced.

The mixture of air and suspended moisture within the grow facility is known as the Gas-Vapor Mixture.

The temperature of the air within a grow room greatly influences the amount of moisture (water) that can be dispersed into the air.

Higher Temperatures  =  Higher Moisture Capacity

Lower Temperatures  =  Lower Moisture Capacity

Temperature Fluctuation can Lead to Dramatic Increases or Decreases in (RH%):

During Evenings | Temperature Drops & (RH%) Similtaneously Increases

During Mornings | Temperature Rises & (RH%) Similtaneously Decreases

Moisture Content of in the Air Surround the Crops being Grown. Greater facility Humidity results in High Concentrations of water in the Air.

Humidity Can Be Defined in (3) Ways:

Specific Humidity | Absolute Humidity | *Relative Humidity*

The First (2) Deal with Ratios of Water Vapor (Moisture) Mass.

Relative Humidity (RH%) on the other hand can be measured using a digital sensor, which is why it’s so commonly utilized over the first (2)

*Realtive Humidity* (RH%) is Expressed as a Percentage of the Max Moisture the Air can Hold Before Condensation Occurs at a Particular Temperature

More Specifically it is Measured as the Ratio of the Vapor Pressure of Moisture in a Sample to the Saturation Vapor Pressure of the same Sample at the Dry Bulb Temperature


Field of Engineering that is Concerned with the Physical and Thermodynamic Properties of Gas-Vapor Mixtures

Enables the Calculation of Various Gas-Air (Moisture-Air) Mixture Parameters Vital to the Health & Growth of Crops

The Temperature and Relative Humidity (RH%) can be Used to Determine Important Gas-Vapor Parameters with the Help of a Special Tool Called a "Psychrometrics Chart". This Chart Enables You to Determine the Value of Any of the (7) Parameters Below so Long as You have (2) Out of (7) Measured (Underlined):

Enthalpy | Dry Bulb Temperature | Wet Bulb Temperature | Dew Point | Humidity Ratio (Moisture Content)  | Specific Volume | Percentage Saturation (RH%)

ABOVE IMAGE | Example of how each of the (7) parameters are determined at a specific Dry-Bulb Temperature (Standard Temperature) and Percentage Saturation (RH%) using this chart. The values of each of the (5) Remaining Parameters are Determined based upon the "Point of Intersection" between Any (2) Measured/Known Variables. Dry-Bulb Temperature and Percentage Saturation (RH%) are use over the other (5) parameters because they are by far the easiest and least expensive to measure on a continuous basis. 

Must Measure Temperature & Relative Humidity (%) Using Electronic Sensor(s) in Order to Use a Psychometrics Chart

Best to Utilize a Combination Sensor that Utilizes Both Temperature and Realative Humidity in One Probe as Shown Below:

ABOVE IMAGE: Shows a high-end, weather resistant, temperature and relative humidity (RD%) combination sensor that is the best option for use in a commerical facility which generally requires a probe with high longevity and durability as well as accuracy. This style of sensor is connected directly to a sensor relay and datalogger which is programmed to precisely control probe's measurement parameters as well as gather data generated. 

The probe should be placed in an area that is completely Shaded from Direct Sun or Lamp Light and incorperates Continuous Air Movement Around (1)(Meter/Sec) in order to accurately measure the temperature & (RH%) within nearly any grow facility. These (2) critical factors effect temperature and (RH%) sensors in the following ways:

  1.  Radiation Heats the Probe causing Temperature to Appear Higher than Actuallity | Similtaneously (RH%) is also Lowered
  2.  Stale Air Keeps the Probe from Sampling the Larger Volume of Air Needed to More Accurately Determine (RH%) and Temperature

  Combatting the (2) factors above is actually a fairly simple process and involves encasing the sensing probe in a "Probe Shielding Module" that's made from (2) Basic Components  -  A light shield to block the sensor from radiation and a fan which generates the optimal (1 m/sec) air movement velocity. Below are the Recommended Specifications for Each Component if building the probe housing module:

(6"L)(3"D) PVC Pipe w/ Cap Modified to Hold Probe  +  (3"D) Computer CPU Fan

ABOVE IMAGE (#): (LEFT) - Schematic of a "Build-It-Yourself" probe shielding module made of modIfied PVC piping + cap and a (3"D) computer fan which draws fresh air across the sensor of the probe. (RIGHT) - Several different styles of probe shielding modules exist including this example of a commercially avaliable temperature and relative humidity (RH%) probe shield which includes a special design that allows air to flow freely through the shield horizontally with the assistance of a HAF fan instead of a computer fan.


Temperature of the Surrounding Environment Required to Reach (100%) Relative Humidity (RH%)

Determine the Wet-Bulb Temperature by Wrapping a Wet Cloth Around a Thermometer and Running Air Over It Rapidly


When Relative Humidity (RH%) is  =  (100%) then,

Wet Bulb Temperature  =  Dry Bulb Temperature 


When Relative Humidity (RH%) is  <  (100%) then,

Wet Bulb Temperature  <  DryBulb Temperature

IMAGE ABOVE: Example of How Wet-Bulb & Dry-Bulb Temperature are Measured


The Temperature Indicated by a Thermometer Exposed to Air that is Shaded from Direct Solar Radiation.

Generally Indicative of How Standard Temperature should be defined and Measured in a Grow Environment.

The Temperature at which the Liquid (Water) in the Air Begins to Condensate or Turn from a Vapor into a Liquid.

Occurs on the Surface of the Crops.

Also Defined as the Saturation Temperature of the Moisture Present in the Air.



Dew Point is the temperature required to achieve complete vapor saturation of (100%) where as Wet-Bulb is determined by wetting a thermometer that's then exposed to a strong air current.

While the results are generally close Dew Point is More Useful for Determining the Temperature the Air can be Cooled to when Utilizing Cooling Methods such as High Pressure Fog/Misting or Wet Pads. 

ABOVE IMAGE: Shows the Relationship Between Air Temperatures (16, 18 & 22 C), Relative Humidity and Dew Point Temperature. For Example if the Air Temp = (18 C) and (RH%) = (70%), then the Dew Point = (12 C). (12 C) is the Temperature Required to bring the (RH%) up to (100%) Saturation. 


Mass of Moisture per Mass of Dry Air with a Range on the Psychometrics Chart from (0) for Dry Air Up to (0.03)(Kg of Moisture per Kg of Dry Air) for Vapor Saturated Air.

IMAGE ABOVE: Shows How Changes in Relative Humidity at a Specific Temperature Effects the Humidity Ratio (Total Mass of Moisture in the Air). As the (RH%) Increases from (40F to 60F to 80F) so Does the Total Mass of Moisture in the Air.


Analogous to the specific volume of a pure substance. However, in psychrometrics, the term quantifies the total volume of both the dry air and water vapour per unit mass of dry air.


The Same Principle as Humidty Ratio except instead of using Mass as the Main Measurement Variable, Volume is Used Instead.


Of ALL the Psychrometric Variables this is the Most Useful for Determining a Dehumidifier's Moisture Removal Rate since it Deals Directly with Volume and All Dehumidifiers are Scaled Based upon Thier (Pints Per Day) Moisture Removal Rates!

IMAGE BELOW: Shows the Realtionship Between Specific Volume (Green) & Humidity Ratio (Specific Density)(Blue) of Moisture in the Air at a Specific Relative Humidity (Black) as Temperature (Red) Increases. 

CALCULATION EXAMPLE: At a Temperature = (75F) and (RH%) = (60%) the Specific Volume = (14 ft3/lbs)

A Quantification of the Total Energy Contained in Both the Dry Air and Water Vapor per Kilogram of Dry Air.

A Representation of the Stored Energy Contained within the Air & Moisture of a Grow Environment Measured in (Kilo-Joules).

Although not the most useful measurement in psychrometrics when it comes to determining the scale of a dehumidifier it does provide growers with an idea of how much energy (and in turn Power) will be required by the Dehumidifier Chosen. 

ABOVE IMAGE: The Temperature of the Water in the Container Increases at a Rate Dictated by it's Specific Heat which is Very High. Indicates Water has the Ability to Absorb Lots of Energy, in the Form of Heat, without Temperature being Significantly Effected. It is for this Reason Water Vapor is Used to Naturally Reduce the Temperature of a Grow Environment.

Cooling Pads/Fans or High Pressure Misting are Commonly Utilized to Release Vapor into the Air Absorbing Large Amounts of Energy Causing the Air Temperature to Decrease as the (RH%) Increases.