Different plants require different environmental conditions to grow. Indoor growing gives you all the power (and responsibility) to maintain these conditions for proper growth – this includes managing the temperature and humidity in your greenhouse.
High humidity and excessive moisture encourage the growth of mold and mildew. To prevent these problems before they damage your crops, commercial greenhouse or grow room dehumidifiers are often a worthwhile investment, depending on your climate.
Commercial greenhouse dehumidifiers come in various sizes and capacities depending on the size of your greenhouse or grow room and the types of plants you are cultivating.
The Best Commercial Dehumidifier for Greenhouse or Grow Room
Best Dehumidifier for Greenhouse: Quest Dual 105 Overhead Dehumidifier
Moisture Extraction: 105 PPD
Airflow Rate: 257 CFM
Drainage: Continuous via gravity with drain hose included
Current: 4.9 A
Voltage: 110-120 V
Dimensions: 21.75” H x 20.25” W x 38” D
Quest is a well known brand of dehumidifiers for indoor growing facilities and other commercial spaces. They come in a variety of designs and functions for your different needs. Some of the best selling commercial dehumidifiers among professional growers are the Quest Dual Series which are designed to operate at 56°F to 95°F.
The Quest 105 greenhouse dehumidifier removes up to 105 pints of water per day at AHAM conditions (80F, 60% RH). It is one of the most energy efficient commercial units with an energy factor of 4.2L/kWh. It has an onboard humidistat with a control knob where you can choose from three humidity levels – Dry at 20-30% RH, Normal at 50% RH, and Humid at 80-90% RH. The unit starts dehumidifying once the ambient humidity rises above the preset level. It shuts off when the humidity reaches 4-6% below the preset.
Overhead installation is highly recommended given the size of the unit, but you may operate it on the floor if there is enough space. Make sure to provide a 2.5” clearance between the unit and the drain pan underneath. The condensate is drained by gravity through the included drain hose attached to the port. The unit is also equipped with an auto defrost function. If it senses frost buildup, it automatically defrosts the evaporator. Supply and return ducting options are available as well. For larger spaces, you may opt for a higher capacity Quest Dual model – the highest can go up to 225 pints.
- High energy efficiency
- Built-in humidistat
- Optional remote control
- Heavy and takes up too much space
Best Desiccant Dehumidifier: Quest Dry 132D Desiccant Dehumidifier
Moisture Extraction: 132 PPD
Airflow Rate: 385 CFM
Current: 22 A
Voltage: 110-120 V
Dimensions: 36” H x 20” W x 20” D
Quest also offers commercial desiccant dehumidifiers for grow rooms. The Quest Dry 132D desiccant dehumidifier is the ideal solution for a wide range of temperatures, from 10°F and 120°F. This unit operates with 132 PPD capacity under AHAM conditions. Like most commercial desiccant units, you may duct the reactivation air inlet from the outside to get a supply of warmer air. This can increase the dehumidification performance in colder conditions.
The Quest 132D can be installed vertically or horizontally with multiple ducting options. It has a simple on/off button to manually start or stop operation. Since it is a desiccant model, there is no condensate formed at any stage. Thus, there is no need for draining. No compressors also means a lighter device.
The unit comes with a MERV 11 filter for the process air inlet and a MERV 8 filter for the reactivation air inlet. The process air enters at 385 CFM through an optional 8-inch duct. The reactivation air enters at 75 CFM and requires a 6-inch duct for the outlet. Ducting and the optional remote humidistat are sold separately. The two installed power cords plug into 115 V outlets.
Quest dehumidifiers are commonly used by indoor growers specifically during the flowering season. The Quest 132D desiccant is best used in combination with a compressor dehumidifier like the Quest Dual 105 Overhead Dehumidifier or another higher capacity commercial dehumidifier.
- Operates at lower temperatures
- Higher capacity than compressor models of the same size
- Energy efficient
- No humidistat
- Higher price than compressor models
Moisture Extraction: 55 PPD
Airflow Rate: 130 CFM
Drainage: Continuous via gravity
Current: 4.1 A
Voltage: 110-120 V
Dimensions: 13.3” H x 19.2” W x 12.2” D
AlorAir is another brand known for high efficiency commercial dehumidifiers. The Sentinel HD55 is one of the best commercial dehumidifiers at its compact size. As the model name suggests, it extracts up to 55 pints of moisture in 24 hours at AHAM condition, and a maximum of 120 PPD at saturation. With an airflow rate of 130 CFM, it covers an area of up to 1300 square feet.
This compact dehumidifier has an Energy Star certification, which ensures high energy efficiency at its affordable price. It has an onboard humidistat that monitors humidity from 35% to 90% RH. If the humidity level goes above the preferred setting, it automatically starts dehumidifying the room.
The unit is equipped with the hot gas defrosting system and operates in temperatures as low as 36F. Once it detects frost on the coils, the unit auto defrosts to avoid any damage that may be caused by frost buildup. AlorAir uses epoxy-coated coils to protect the device against corrosion and freon leakage. The unit is backed with a five-year warranty.
You also have the option to use a remote humidistat to control humidity levels, which makes this dehumidifier perfect for tight spaces or harder to reach areas. Due to its size and capacity, the Sentinel HD55 is also ideal for residential use in basements or crawl spaces. One downside is it doesn’t come with an automatic drain pump, which means you need to attach a pipe and place the unit above a drain.
- Energy Star certified
- Small and compact
- Most affordable model with its capacity
- No built-in pump
Best Dehumidifier for Cold Climates: Ecor Pro DryFan 50 pint Desiccant Dehumidifier
Capacity: 25 PPD
Airflow: 84 CFM
Current: 4.6 A
Voltage: 110-120 V
Dimensions: 8” H x 8” W x 11.8” D
The smallest unit in our list is the Ecor Pro DryFan desiccant dehumidifier. Desiccant dehumidifiers are known for low temperature and quiet operation. This light and compact dehumidifier removes up to 25 pints of water per day in temperatures between -4F and 104F. It operates with an airflow rate of 85 CFM and covers up to 1,000 square feet. It uses the three hole system – there is one inlet for the two air streams and two separate outlets. The process air outlet may be ducted into the controlled space.
Since the DryFan is a desiccant model, there is no need for draining. You may place the unit on the floor or even mount it on the wall or ceiling. With its compact design, one person can easily carry and install the unit. Built with stainless steel interior and exterior, it can handle harsh conditions and last for a long time.
It self-regulates to ensure efficiency at any temperature and humidity level. It also features auto restart in the event of a power interruption. There is an option to connect the Ecor Pro EPHUM220 humidistat for remote operation and control. Due to its capacity, you may need to operate multiple units or use it in combination with other models. For smaller areas, like a 6×4 feet greenhouse for example, the DryFan may be enough.
- Light and compact
- High durability
- Easy use and maintenance
- No humidistat
- Small capacity
Best Dehumidifier for Large Greenhouses: Aprilaire 1820 Pro Dehumidifier
Capacity: 70 PPD
Airflow: 200 CFM
Drainage: Continuous via gravity with drain hose included
Current: 5.8 A
Voltage: 110-120 V
Dimensions: 12.5” H x 12.5” W x 25” D
The Aprilaire 1820 Pro is a high efficiency dehumidifier with many uses both in commercial and residential areas. It has a 70 pint capacity and an airflow rate of 200 CFM. With a coverage area of up to 2,800 square feet, it is great for mid-sized greenhouses, commercial spaces, and even for whole-home dehumidification.
The unit features a simple, interactive display that is easy to set up and use. The control panel is mounted on the front of the unit for your convenience. Set it and forget – the 1820 Pro starts dehumidifying once it senses humidity above your desired level. Just attach the included hose to the outlet or place the dehumidifier over a drain and leave it to work.
Built with corrosion-resistant aluminum coils, it is guaranteed for long-term use. It is backed with a five-year warranty from the manufacturer. It also comes with a filter that only needs once a year cleaning or replacement. At 56 pounds, the unit shouldn’t be difficult to move and set up. One downside is it doesn’t come with an internal condensate pump, which limits your drainage options.
- High durability
- With built-in humidistat
- No condensate pump
What to Consider Before Buying Greenhouse or Grow Room Dehumidifiers
One of the most important factors you must consider before buying a commercial dehumidifier is the size of the greenhouse and the size of dehumidifier you need. Make sure the dehumidifier or chain of dehumidifiers can cover every corner of the area. If you’re low on space, some models are specially designed for overhead installation. Some may also be mounted on the wall or ceiling with hanging brackets. In any case, it’s essential to get the right size dehumidifier for your space.
Another important consideration to make when purchasing a dehumidifier is the amount of moisture present in the environment. The maximum capacity of a dehumidifier is the largest amount that it can extract per day at the ideal condition of 90°F and 90% RH. The AHAM capacity is the amount collected at the average condition of 80°F and 60% RH, as dictated by the Association of Home Appliance Manufacturers.
To know which pint capacity is best, consider the number of plants in your grow area and the amount of water they need. As a rule of thumb, each plant requires at least 4 pints of moisture removal per day. If you have 10 plants, for example, opt for at least a 40 pint capacity or get two smaller 25-pint units.
Most compressor models give you the option for continuous draining via gravity. Simply attach the appropriate hose onto the outlet, then place the device above a low-level drain or direct the hose into the drain or sink, and let gravity do the work for you. Some heavy duty industrial dehumidifiers like the Dri-Eaz Revolution also come with an internal condensate pump to automatically drain the water in any orientation. Desiccant dehumidifiers, on the other hand, do not pump out water. They extract moisture from the desiccant material through a warmer, second air stream which then exits the room through a duct.
Low Temperature Operation
Most refrigerant-based commercial dehumidifiers feature auto defrost to prevent ice buildup inside the machine when temperatures drop to 33F. They use different technologies to protect the internal components from frost and its potential damage. When it senses low temperature the unit shuts off automatically to defrost, then starts back up again. Desiccant models are especially known to have the ability to work in much colder conditions. Commercial desiccant dehumidifiers remain efficient even at 0F, depending on the model.
Built-in sensors make it extra convenient to keep track of the temperature and relative humidity in the greenhouse. You can set your desired humidity and the unit will shut off automatically once this level is reached, thus reducing your energy consumption. If you need to maintain a specific humidity setting in the area at all times, you may want to look for a dehumidifier with an onboard humidistat that operates continuously.
To save on costs, you need a versatile dehumidifier you can use on different occasions. For easy movement, you want a unit as light and compact as you can get. Most commercial dehumidifiers are built with rigid handles and wheels or leveling feet for added portability. Since they do not have big, heavy compressors, desiccant models are generally lighter and more compact. The smallest unit in our list, the Ecor Pro DryFan 50 pint, is as light as 14 pounds – which can easily be moved and installed by a single person.
If you opt to install your dehumidifier overhead with hanging brackets, it may be a hassle to operate manually. You have the option to integrate a remote humidistat for easy control and monitoring. Some models also offer optional ducting to maintain the temperature and humidity level in controlled environments.
Benefits of Using a Commercial Dehumidifier for Greenhouse
Humidity is absolutely essential in the growth and health of plants. The right temperature and humidity must be maintained depending on the type of plant and stage of growth. High humidity can be harmful to your crop. Excessive moisture may cause fungal infection which affects the plant’s ability to absorb water, light, air, and nutrients from the leaves or soil. If you see white fuzzy mold or powdery mildew on the leaves or stem, this is a sure indication of high humidity. Mold infestation also causes unpleasant smells in the environment.
Excessive moisture may also cause condensation on the roof or walls. Once the water drips back down, it can contaminate nearby crops and spread mold infections or other plant diseases. It could be more costly to have to treat an entire area of your greenhouse instead of preventing mold growth from the beginning.
Types of Commercial Dehumidifiers and How They Work
There are two main types of dehumidifiers that use different methods of collecting moisture from the air: refrigerant and desiccant. A refrigerant dehumidifier draws humid air from the environment and pumps out the moisture extracted. It uses the refrigeration cycle to reduce humidity. As the warmer, humid air passes through the cooling coils, moisture condenses into water. This water is then pushed out through a drain or pump. The dry air is reheated and exhausted to the room to collect more moisture.
Since this type of dehumidifier uses refrigeration to extract moisture from the air, its performance declines dramatically when the air becomes colder than the refrigerant coils. They cannot go below freezing point or the condensate will form ice. This can occur at about 65°F/18°C or below. For highly humid and warm environments, refrigerant types are the ideal choice.
Meanwhile, a desiccant dehumidifier uses a chemical which collects moisture from the air through adsorption. The first stream of humid ambient air passes through the desiccant rotor. The desiccant material takes more and more moisture until it is fully saturated and the now dry air reenters the room. A second air stream enters the dehumidifier and passes through a heater. This warm, dry air removes moisture from the saturated desiccant and exits the dehumidifier. Since they do not use condensation, desiccant dehumidifiers are efficient in cold conditions that a refrigerant model cannot handle.
How to Control Humidity in a Greenhouse
Installing a dehumidifier is the best way to lower humidity and keep optimum levels in your greenhouse but there are other easy ways that may help. First is by controlling the temperature to prevent moisture from condensing on the leaves or the greenhouse walls. Keep the area warm during nighttime and maintain consistent temperature.
It is also essential to have proper ventilation in order to lower the humidity. Flowing air removes excess heat and carries moisture away from your plants. Put enough space between the pots to allow for air circulation. Pair your dehumidifier with fans or air movers to maximize moisture removal. If it’s safe, open a vent or door to increase ventilation.
To prevent extra moisture from accumulating, avoid too much watering and always drain any stagnant water in the area. Puddles of water may also become a breeding ground for pests. It’s best to water in the early morning to allow water to reach the roots instead of evaporating. This also lets the plants dry before nightfall.
How do you prevent mold in a greenhouse?
The best way to prevent mold and mildew growth in a greenhouse is by maintaining inhospitable conditions, lowering the humidity, and removing excess moisture.
What is the ideal humidity for a greenhouse?
A good range is around 50% to 70% RH at 80F to 85F.
How do you dehumidify a greenhouse?
The easiest method is by providing enough air circulation and proper ventilation. Proper watering and adequate spacing between plants must also be observed.
Where should you place a dehumidifier in a greenhouse?
Ideally, a dehumidifier must be placed where it can cover the entire area and address your humidity problems at its main source. It is also best to place it as close to the power supply as possible, and at a distance from your crops.
Greenhouses provide a stable environment for certain crops to grow year round. A healthy crop needs just the right conditions in every stage of growth. It is important to control the temperature and humidity in the greenhouse for optimal plant growth. Before high humidity and excessive moisture can cause a variety of problems to your harvest, it is best to observe proper care and maintain your crops in healthy shape. Commercial dehumidifiers are best for constant humidity control. Depending on the size of your greenhouse, its current state, and the requirements of your plants, you can find a dehumidifier for your specific needs.