Air to air heat exchanger for lowering temps

[Tsitka]

Temps are too high, looking at using an air to air heat exchanger to lower the temperature in the lung room from the CO2 generator. AC currently 2 3 ton units and I'm not quite ready for a third 3 ton.
Has anybody gone this route? The air from the outside would basically come in and back out, the CO2 enriched air would pass through over the coil. Not a lot of ducting required and HRV's are cheap with low power requirements.
Thoughts?

 

[queequeg152]

hrv's are NOT cheap. they are insanely expensive.

you would be better off injecting co2 into your make up air.

consider an economizer module with an actuated damper on your return air ducting. when properly set up, it should be able to determine on its own when outside air temps warrant its use.

you could conceivably incorporate a more complicated system whereby a volume damper is used in conjunction with air stream temperature sensors + outdoor air temp sensors + humidity sensors to calculate so called 'air enthalapy'. the end result being that you could blend inside and outside air flexibly depending on outdoor temp and humidity.

i wouldn't recommend the latter however. a regular economizer setup should be more than enough to meet your needs, provided you size the equipment properly.

you should have a media air cleaner in front of the coil such that the make up air taken from outdoor is filtered properly. otherwise dust and shit kicking off of your roof or from lawn mowing will be brought inside.

 

[Tsitka]

I use mini splits and have access to an HRV for a grand. The plan is to route ducting over the top of the propane burning CO2 generator, have the air go through the HRV coil and into the room. The outside ambient air would come into the unit and back outside.

 

[queequeg152]

whats its volume though?

a grand is about what they cost. 2 grand for a larger 100+ cfm unit.

problem with these household units is that they are insanely small. you would need like 40 of them to cool something like a 64kbtuh heat load.

they are not meant to cool the house... only to cool or heat the make up air that you are required to ventilate to meet IAQ standards for tight home construction.