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kurtos

Winter vs Summer air exchange

kurtos
11 years ago

So I'm trying to figure all this exchange rate stuff out. I have a 10x12 self built poly carb greenhouse. Most calculators out there give me around 1400 cfm requirements. I know I need to exchange the air about once per minute in the summer. This I get and can apparantly be accomplished with a 12" exhaust fan and a 12" intake vent.

My problem is during the winter/colder months. From what I gather I need an exchange rate of 2-3 per hour. I'm not sure if a variable speed exhaust fan would do this or not. One I was looking at from littlegreenhouse.com will do a minimum of about 600 cfm. This has got to be way more than 2-3 per hour. Guess I just don't get how two different exchange rates are achieved with one system.

My biggest problem is I have a blue flame Mr Heater that always shuts off due to lack of oxygen. I would like to fix this problem as well as get the air exchange I need all at once if possible. Currently I have run a 4" pipe from the outside to directly under the heater as suggested on another post. This however hasn't solved the oxygen issue. Thinking of maybe using an inline duct fan from home depot to draw more oxygen in. Anyone had success with this?

I do have some circulation fans which I always keep on to help maintain even temperature. When it gets to hot I just blow air out the door. I would like to increase the effectiveness of this system with a normal exhaust fan setup.

Open to all criticism/ideas on this one. Thanks!