On the contractor side, Tomarchio has overseen HVAC for projects ranging from a small 400-sq-ft room to, more recently, a 60,000-square-foot building.

Ask Tomarchio about grow facility particulars that HVAC contractors should know about, and he is ready with examples.

FROM SMALL THINGS: Angelo Tomarchio, owner of Americare Heating & Air in Norman, Oklahoma, has seen inexperienced clients start in small spaces, refine an approach that works, and pursue multiple expansions. (Courtesy of Cannabis Tours (CC-A 4.0))

O₂, CO₂, and You

Outside air is not a novel concept. It’s a building code staple. Nevertheless, a lot of growers don’t want any outside air, Tomarchio said. So that can mean a conversation about the benefits of fresh air.

Tomarchio then pursues the goals of cultivation, fresh air, and exhaust. In this environment, mechanically bringing in CO₂ is desirable while still “scrubbing” the room with fresh air.

“Within that realm, we were designing things a little differently,” he said.

“Carbon monoxide hangs low in the atmosphere. So if you are going to pull in fresh air, we recommend that you pull it in low,” he began. “Then you exhaust up high, so that literally your trunk run would run the full length of the building on one side. And supply holes, ported out, coming out underneath the canopy of the marijuana. And then it would exhaust on the opposite side, up high, at the roofline.”

That solution creates another problem: introducing CO₂ into the space necessitates an emergency setup for evacuation.

“So now, you're splitting your exhaust where you've got a point up high, and you're breaking that leg and putting a damper system and dropping another pipe down onto the ground,” Tomarchio said, “because you have to be at least 12 inches or lower on the ground for the intake for CO₂ evacuation.”

In one way, the system now entails three different systems — or maybe just two: one for occupancy and one for CO₂, if the owner is adamant in skipping outdoor air.

All-In One Advances

Equipment is evolving to meet the menu of demands for grow facilities, and contractors could do countless residential or commercial jobs without ever needing to see it.

These units can attack dehumidification, heat or air conditioning as the moment requires, and outside air needs. The high-end combo equipment is made more specifically for a horticultural or laboratory area.

Tomarchio explained that these units may include “fresh air intake loops that you can add, that are controlled by a damper to pull in fresh air to qualify for your occupancy” needs, while also offering higher filtration than a standard package unit.

The equipment can also compensate for one of a cannabis grow facility’s most unusual demands: needing to run the air conditioner when it’s 15°F outside.

“Now they have low ambient controls, so it will adjust the motors, the compressors, and the fans to cool that area as if it was a 90° day outside when it's 15° or lower. And still get a full capacity on your Btus.”

Water Cooling Meets the Laws of Nature

With that, a contractor has theoretically conquered ventilation needs, a CO₂ component, and how to cool a grow room in a blizzard. What could possibly be left to deal with?

“Now you’ve got a drain line,” Tomarchio observed, for a packaged unit outside, and when the system is cooling in subzero temps, it contains condensate that is waiting to freeze up.

A system might also have an inside condenser or inside air handlers that are draining outside, he noted.

“You have to add some kind of heating rope or heating element to the line.”

Tomarchio has seen drain lines freeze during severe cold despite the benefits of insulation and heater tape.

Defrost sticks like ones used in walk-in refrigeration can work, he said, but in order to wrap around the line, they require 220 V plugs outside. Not many facilities will have been designed with that capacity.

In that case, a contractor may be left trying to cut the drain line, put the brand new line on, wrap it with a 110 V heat strip, and/or insulate it with ¾-inch Armaflex, Tomarchio said.

In a pinch, cutting off the line right at the wall and then sticking a piece of string in the drain line has worked.

“That water will follow that string, creating a little drip-down with an icicle,” he explained. “But that, too, will only last so long.”

It might get a facility through a week of exceptionally steady cold, though, even if someone may need to occasionally go outside with a hammer and tap to try to knock some ice out.

It's a Jungle In There

Of course, this chain of grow-specific challenges and solutions is just the tip of the iceberg for proper HVAC installation and maintenance in these spaces.

Humidity control remains a critical task. Dehumidification may get more attention, but Tomarchio will walk a listener through the why’s and how’s of keeping both temperature and humidity a bit higher at stages than conventional wisdom might suggest.

“This is probably more of the grower in me talking, but good marijuana is usually a jungle-type plant,” he said. “It likes some high temperatures, and it likes humidity. It’s a weed. You know the grass that's growing in your sidewalk when it's wet, and hot and humid? It’s kind of the same thing, especially in the vegetative state.”

So where growers commonly set temperatures at 80°F, Tomarchio prefers 85 up toward 90. After all, he argues, there are 90° days outside, so as long as water and humidity are adequate “and you’re not killing them with your lights, you can replicate that into a controlled indoor environment.”

Contractors in this space would need familiarity with simple portable oxygen concentrator (POC) humidifiers, but also with the pros and cons of steam humidification, too, as the next step up.

Not content with available options, Tomarchio has designed a unit for some of Americare’s projects. It combines ultrasonic mist with disc technology like that used in humidors and settings with similar needs. He likes its ability to deliver superfine mist without getting “drippy” like some units and without other units’ occasional calcification or “burping” water on the floor.

Clients and Competition

In Americare’s market, Tomarchio sees the customer base for cannabis grow facilities getting larger these days. Potential clients are also better informed and more serious, on the whole, than some guy looking to “throw up quick garage setups.”

Some customers who may have started with little experience have done well in the business and gotten smarter along the way. Tomarchio has seen some of them start with a small room, then build out another 3,000-square-foot room. And then another 3,000 square feet, and then another.

But others can still roll in espousing what Tomarchio calls “‘Hey, bro’ science.”

That happens after the client has a conversation with someone whose bright idea is uninformed or lacks context. Maybe a client was talking about strategies in a shop or online community and someone told them, “Hey, bro, you should get your grow room’s humidity down to 40%.”

Tomarchio offers consulting services in addition to contracting, in part for situations like that. This is not only useful for some customers in achieving a better design, but for the sake of both Americare and the client, it can nip a variety of potential technical and contractual issues in the bud before installation gets going.

Tomarchio expects a market bubble to develop and work itself out. Those bubbles always attract some contractors looking to make a quick buck, too. Americare has benefited from a number of projects where a grower had a terrible experience and hires Tomarchio to come in and deal with the HVAC mess.

Looking beyond the quick buck has served Americare well so far.

“I want the contract,” said Tomarchio. “I tell them, ‘Hey, I want to see you every three months, want to come in here and maintain these machines and clean them all and test them all, and run them through diagnostics and make sure there's no issues going on.’”

“If there is an issue, what can we do? Nobody's perfect. I might put an extra bend in the pipe, which lowered my back pressure on the pipe, and now one part of the room was a little bit warmer or colder. You know, okay, how do we adjust that one little section there?”

In this sector, successful clients and knowledgeable HVAC contractors can still find room to grow.