Fan Coil unit "Dirty Sock" Odor

[OscarMeier]

We have a problem with fan coil units having a "Dirty Sock" odor problem. This odor starts when a a unit switches from heating to cooling mode. The probelm is only when the unit changes from an extended period of heating over to cooling and seems to last only 15 to 20 minutes into the cooling cycle.

The odor can be fairly strong - we've tried a biocide pellet in the pan with little sucess.

Any thoughts - cause / cure?

 

[imok2]

This may be of some help:

http://www.dustless.com/alpha/chemicals/purcool.html