Indoor grow rooms give gardeners complete control over their climate. However, all of the equipment needed to regulate this temperature- and humidity-controlled environment can create excess heat, which can stress out plants and reduce their quality and yield.
If you want a cannabis grow room optimized for success, you are going to need a complete HVAC system. Our grow room HVAC guide breaks down the most important components of an indoor growing cooling system and how to find one that meets your needs.
Investing in an air conditioning system is a great step toward optimizing your cooling in your indoor garden, as long as you invest in the right unit. When shopping for an air conditioner, consider these common types of systems.
Portable Air Conditioner
Portable air conditioners are convenient and efficient and can be quickly and easily moved from one area to another. Their compact size makes them good for smaller grow rooms or grow tents.
Generally, there are two main portable unit types that include either one or two tubings. We recommend investing in the units with two tubes since it will not bring the exhausting heat back into the room.
Window-Mounted Air Conditioner
Window-mounted conditioners are more complex to install than portable units. This type of AC can be attached through the wall or window in which half of the unit is exposed. A window-mounted conditioner is perfect for small to medium-sized gardens.
Mini-Split Air Conditioner
Mini-split air conditioners are usually ductless units that come in two parts: one is the rectangular unit mounted on the wall and the other is connected outside to remove the heat and moisture during cooling.
Multi-zone systems enable you to keep multiple rooms or “zones” cool at different temperatures. It can be a great choice if you plan on maintaining several grow spaces in your home or facility.
Mini-split systems are more technically complex to install and may require professional installation. Only install these if you have a permanent grow room environment, not a portable or temporary one.
Ceiling Mount Air Conditioner
Ceiling mount air conditioners are good for rooms that don’t have a lot of storage. These units work similarly to mini-split air conditioners but are mounted on the ceiling. Using these units could maximize your garden space. However, they may require professional installation which can increase overall upfront costs.
Commercial Grade Air Conditioning Unit
Commercial grade air conditioning units are designed for large-scale facilities and can also work in greenhouses. Commercial systems are larger than other units and are typically mounted on top of a grow room facility. These will require professional installation and should be installed on buildings that can handle a commercial-grade air conditioner.
A quality ventilation system will remove hot air from your garden to keep your plants cool and healthy. Consider investing in industrial-grade inline and oscillating fans to improve your control over the climate and save on electricity.
- Inline fans are in the ducting and remove hot and humid air from your indoor garden.
- Oscillating fans can be clipped onto grow tent poles or stood on the floor for better air circulation.
Fans should create a gentle breeze around the canopy area, just above and below the plants. Pointing fans directly at a cannabis plant can increase the risk of damage.
Fans are affordable investments that can bring in fresh air and reduce excess heat and humidity in grow rooms. Fans can work with the HVAC system and lower your overall energy costs.
On top of the excess heat, grow rooms may experience excessive humidity which can make them feel hotter than they actually are. Dehumidification systems can help reduce the risks of mold or rot.
Always look for a large-space or whole-house unit. Smaller units do not offer the dehumidifying power needed for large grow rooms. In addition, invest in a hygrometer to check your grow room’s humidity levels.
Water Cooling System
Water cooling systems pass chilled water through most or all heat-producing equipment such as lights and dehumidifiers to reduce their total heat output.
By making a water cooling system a part of your HVAC system, the need for air conditioners is reduced. A water chiller can cool the water before it is circulated through a series of coils throughout your equipment.
Water cooling systems are reserved mainly for growers who live in warmer areas where it is hard to maintain a consistent temperature.
Factors to Consider When Shopping for Grow Room Air Conditioners
When looking for an air conditioning system for your indoor environment, consider these factors before making your final decision.
Stationary or Portable
Do you need a stationary air conditioning unit for a permanent and large-scale room? Can you work with a portable one for your small grow room environment or grow tent?
A compact and portable unit can be good if you have a temporary garden since you can move your unit whenever you need it.
Consider how much cooling power you need for your desired production and then add a buffer on top of your cooling requirements. Experienced growers know to add a buffer of about 20% more than they need so that they can be prepared for any variables that can change over time.
While investing in a high-quality air conditioning unit may have a higher upfront cost than buying a cheaper version, you will be better prepared for future growth.
Most indoor growers prefer air conditioning units with dual exhaust hoses over a single-exhaust hose.
A single exhaust hose can remove the cool air from inside the room and leave your room hotter.
If you live in an area that has very warm temperatures, a dual exhaust hose is critical in removing warm air while keeping the cold air in your grow room environment.
For streamlined growing, a self evaporative system, also called a no-drip unit, can eliminate the need to drain the AC’s water daily.
Instead, the self evaporative feature recycles about half of the condensed water and uses it to cool off the inner cooling coils for more efficient and powerful cooling. Then, it evaporates the leftover water into the outside air with the hot air from the back.
Investing in the most energy-efficient capabilities can optimize your energy usage and reduce your overhead costs in the long run. Look for units with the highest Seasonal Energy Efficiency Ratio (SEER) logo. Air conditioning energy consumption can be offset with fans.
Reputation and Reviews
Look for brands with a reputation for producing quality HVAC systems and check out the brand’s customer reviews to see how well the equipment has worked for other customers.
Warranty and Customer Service
When investing in cooling equipment, look for money-back guarantees or extended warranties. In addition, ensure your manufacturer can provide quality after-purchase services to answer installation or troubleshooting questions.
Some air conditioning systems have several capabilities rolled into one such as air conditioning, dehumidifier, and fan. Investing in these units can save you money and energy instead of buying and using several pieces of equipment.
Grow Room AC Sizing
When setting up an HVAC system, one of the most important things you need to do is calculate the right amount of British Thermal Units (BTUs) in your grow facility. Make sure to consider the amount of heat being produced by your entire lighting setup.
Choosing a unit that doesn’t provide enough cooling power will run more continuously which can waste energy and reduce the longevity of your unit.
However, a unit that has too much power can cause it to short cycle, which would get the room to the desired temperature and then turn itself off. Then, it turns back on to maintain the ideal temperature. The constant on and off cycling can waste energy and shorten the lifespan of your unit.
Air conditioners are rated by BTUs referring to the amount of heat they can remove from a grow space. Commonly, air conditioning units have the following BTUs:
12,000 BTUs represent about 1 ton of air conditioning capacity per hour. Generally, 1 watt of HPS light requires about 3 BTUs of cooling. However, having about 20% extra capacity is recommended for environmental variations.
For HPS lighting, follow the following formula to determine the total BTUs:
(3 BTUs) x (1.2) x (total watts of HPS light) = total BTUs needed.
HPS bulbs can create excessive heat and increase your overall energy needs and costs. Switching to LED lights can reduce the heat created by HID lighting systems such as ceramic metal halide lights.
When determining the total heat production in your grow operation, consider the heat output of the following equipment:
- Grow lights
- CO2 burner
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