Fan?

[bigtau]

I have what I probably a stupid questions....

I'm thinking about building a fermentation chamber and have read through several threads here. I've noticed most, if not all, of them have a small fan mounted inside. What is the purpose of the small fan? Obviously for circulating air, but why?

 

[Cpt_Kirks]

They help keep the temperature uniform, and prevent hot or cold spots.

I have never found the use for one in my chiller, but some designs might need them.

 

[Beer_Guy]

Without a fan to move the air around it will stratify. The colder air will settle and warmer air will rise. The air down at the base of your carboy or bucket might be 20*+ lower than the air up top. It will also of course be lower than what the thermostat reads were it is.

If your chamber uses a fan when it comes on, it will mix these different temps and run until the mix is at the desired temp.

If no fan is used at all, the cold air produced will settle and the unit will run until the temp at the thermostat reaches the desired setting. This means the air on the floor might get really cold before shut off.

A small fan running all the time will help keep the temp even throughout the chamber. This will shorten the on time for the unit by not having to cool all that extra warmer air up top.

 

[bigtau]

Thanks for the info. This has helped out alot.