How do you decide what size fan to put in the greenhouse?

[Guest]

Mine is 12x14 or so. My fan went out. I need a new one and think the old fan was not the right size. In the winter the air is stagnant and plants stay wet too long. I am very careful not to have access water in the gh at all times.

I am wondering also about an isolating fan. It will be mounted on the ceiling unless any of you have better advice.

[Scott]

One big one for ventilation (summer).
Several small ones for circulation (Winter).

[Rick]

I used CFM as a guide for mine and went way overboard. Mines a solar powered one though so it’s not always on but when the suns shining it will suck the door shut. It is 12” 12vdc.

Mine specs out at needing 384cfm but my fan is supposed to move 3000. It only could do that in direct sunlight though.

[Batman]

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