HVAC professionals - Can I split the input/outputs of air exchange system (HRV)?

[weimer222]

I have an air exchange/heat recovery system in my house. I really would like to tap into the input and output of the duct used in this system for my grow room.

I am wondering if I can put y-fittings immediately at the input and outputs of the air exchange system duct work. I would then put dampers on both legs of the y-fittings so that the grow room and air exchange system air stay separate.

Is this doable? I don't want to unbalance my air exchange system, yet also don't want to add two more holes on the outside of my house to accommodate my grow room ventilation if I can avoid it.

If the y-fittings will work, do I have to oversize them to accommodate both systems using the same input/output? I wouldn't think oversizing is needed unless both system are on at the same time, which is certainly possible. Currently, the air exchange input/outputs are for 6" duct. Would I have to make the openings 8" along with the y-fittings? I'd then use 6" reducers on each leg of the y-fittings to accommodate the 6" duct for the air exchange system and grow room.

I would really like some professional advice before proceeding.

 

[smoke3]

Im not a pro but this is what works for me.

Im the room there two vents, the intake and the return. my carbon filter runs thru the lights and up the return, while the intake pumps air into the room.

I maintain a 78degree room while the rest of the house is 75, to counter act the hot air in the return vent i move the thermostat to the coldest part in the house, I set the thermostat fan to always on so there is always a constant flow of air in the room. I also rigged a carbon filter under my handler for added security. this stays on 24/7 and acts as a booster for the handler fan.

Because the carbon filter is using a higher cfm than the handle the room has negative pressure so all the air in the room gets sucks thru the filter and throw out the house and back into the handler.

I havent experience any issues with my ac except that i had to clean the fins because the previous house owners never did.

Im still trying to firgure out running co2 in that room with a air exchange im almost there just working out a few kinks. The plus said to the return system is during the colder months u can use the heat in ur room to warm the whole house. freeing up 4k from the ac unit

 

[weimer222]

I understand the basics of ventilation and am planning something similar, except I will have a separate intake for my air cooled lights.

What I want to be sure of is that I am not unbalancing my air exchange system or causing other issues by tapping into the HRV duct work.

 

[weimer222]

Anyone?

 

[growingcrazy]

You can tee the grow room off of the heat and return ducts for your whole house hvac. If you do this I would put an inline damper on the intake side. That way it is only open when the room needs heat. If you also do this with a thermostatically controlled damper you can open the vent and turn the heater on at the same time. It works very well. You are still going to need some source of exhaust fan though. Unless the heater is running your not going to be moving any air. Also unless you have seperate ducting all air brought in for ventilation or exhaust will be ran through the heater ducts. I would say 2 seperate forms of ducts...One from the heat run and the cold air return, and another that is vented to another room in the house for intake and exhaust with a fan running 24/7.

 

[weimer222]

You can tee the grow room off of the heat and return ducts for your whole house hvac. If you do this I would put an inline damper on the intake side. That way it is only open when the room needs heat. If you also do this with a thermostatically controlled damper you can open the vent and turn the heater on at the same time.

I want to tap into my air exchange unit. Air exchange units are used for bringing fresh air into homes that are well sealed and don't breath on their own very well. Thus, I am only going to bring in cold, outside air for the intent of cooling my lights. I will have a separate fan bringing in this cold air to the grow room, using separate duct work from the air exchange unit. This air will go through the lights and then back outside via a separate run of duct.


In the following image, which is overly detailed of an air exchange system, I've indicated where i want to tap into the air inputs/outputs with y fittings. Each y-fitting would have backdraft dampers so air from the air exchange system and my grow room will not mix.

[URL=http://img231.imageshack.us/i/ductwork.jpg/] [/URL]

So, getting back to my questions, will the y-fittings with backdraft dampers allow my grow room ventilation system and air exchange system to coexist efficiently? My only concern is if both systems are running at the same time will the 6" opening for the air inlet and outlet be sufficient? If 6" is needed for the air exchange system and I will be also using 6" duct for the grow room, do I need to oversize the inlets and outlets to accommodate both systems from intaking and outaking at the same time?