Air conditioning is essential, expensive equipment when you have an indoor marijuana grow room.
But many cannabis growers have an incomplete understanding of grow-room air conditioning.
Their lack of knowledge may create higher grow room costs, degrade crop outcomes, and lead to fire or other dangers.
This is the first article in a series about marijuana grow-room air conditioning issues.
Not for Amateurs
Most marijuana growers want to keep their grow room a secret, for obvious reasons.
We network with each other on cultivation forums and elsewhere to figure out how to build, equip and run an indoor grow room.
But sometimes, amateur advice is dangerous.
And one of those times is when you’re considering what kind of air conditioning system, equipment and structure you need for your indoor marijuana grow room.
Even though there can be security risks involved in doing so, we suggest you use a licensed electrician and a licensed heating, ventilation and air conditioning (HVAC) contractor.
This seems like scary advice, especially if you need help with air conditioning issues and you have a grow room with plants in it.
We don’t want anyone to know we have a grow room.
We don’t want anyone to know we’re planning to have a marijuana grow room.
There are ways to deal with security issues that can occur when you call in professionals to help with your HVAC needs, and we’ll discuss these in a future article.
But the simple fact is that only a skilled, licensed HVAC professional fully understands the dynamic interactions between the entire building and the cannabis grow room.
Installing and upgrading air conditioning systems isn’t a job for amateurs.
For example, many growers install an exhaust fan to suck the hot air out of their grow room.
But it’s also sucking air out of the rest of the house, unless the grow room has a totally sealed door.
When you have a whole house air conditioner operating at the same time a marijuana grow room exhaust fan is operating, you could be sucking cooled air out of the house.
You could also be creating a backflow situation in which air, dust and disease vectors (such as mold spores) are sucked into the house through cracks in window frames, doors, door frames, or faulty roof and attic seams.
Your electricity bill might go up, because air-conditioned cool air is leaving your home via the grow-room exhaust fan!
When we as amateurs try to guess at air conditioning upgrades and installations, we often make mistakes.
Generic Calculations Aren’t Good Enough
Many growers use simple, generic grow-op folklore formulas to calculate how many tons of AC cooling power they need per 1000-watt high-intensity discharge (HID) grow light.
These formulas are based on estimated BTUs (heat units) associated with operation of each 1000-watt HID light.
Unfortunately, these generic formulas aren’t reliable.
A thousand watts of grow room lighting from LED grow lights won’t generate as much heat as a thousand watts from an HID grow light.
And a 1000-watt regular HID bulb doesn’t generate as much heat as a 1000-watt double-ended bulb.
There are even differences in bulb heat based on manufacturer, and on the type of bulb components and gases.
If you intend to use cooled grow lights, if your ballasts are in your grow room instead of outside it, if you use more or fewer aerating fans, if you use a dehumidifier and/or CO2 burner, if you install a wall air conditioner split unit — any or all of these factors change how many BTUs of heat need to be dealt with in your grow room.
Further, the size of the grow room, and the size of the rest of the building, impact air-conditioning capacity calculations.
Some growers deal with these issues by creating a totally sealed grow room and installing a split unit into the grow room wall.
This might simplify some aspects of the building’s air conditioning load, but could also add complications.
For example, if you have a whole house air conditioner, and then you install a room air conditioner, you increase electrical loading, and added another unit that sits outside your house.
Most air conditioning upgrades require changes to electrical infrastructure.
This explains why HVAC techs often require the homeowner to pay a licensed electrician to install new wiring, upgrade main panels, or otherwise alter the building’s electrical system as part of an HVAC new installation or retrofit.
Yes, I realize that getting involved with licensed electricians and HVAC contractors creates a security risk for cannabis growers.
There are ways to mitigate the risk, and we’ll get to that later in this series.
For now, the main thing to realize is that creating an air conditioning system that allows you to cool a marijuana grow room in your home requires more than just adding a half ton of AC capacity for every 1000-watt light you run.