RE: Mold problem in 4°C room

Deitiker, Philip R via (by pdeitik from
Thu Nov 5 18:55:17 EST 2009

Mold grows in cold rooms because moisture collects on surfaces before being picked up by the evaporator coil on the refrigeration system. Many newer cold-rooms have a drying system on them to prevent the build-up of mold. They are expensive.  

In addition people who store live culture in the walk-in coolers have the most problem, because many volatile compounds can be effectively utilized by mold, and particular on wooden and paper surfaces. It is best to keep living culture wrapped or sealed tightly and to keep organic volatiles such as acetic acid, ammonia, amines, sulfides, etc sealed tightly. 

One can deal with mold as described below. If the wooden surfaces in the room are wood they have been varnished, the mold and moisture eventually destroys this and a surface such as Stainless steel or polyurethane treated wood may be preferable. Corion or stainless steel works well for table tops. 

One very common cause of mold is an improperly working fan-coil unit (the aspect of the machine that transfers air across the evaporator coil). This unit is supposed to pick up moisture and deliver that moisture to its condensate pan, were the condensate is rapidly drained. The condensate pan must be level on the outside edges and drain to a center position and quickly out of the cold-room. It is a frequent occurrence that the fan-coil unit is not doing this properly, the condensate tray builds up water and eventually waves form of the surface. The tops of these waves are picked up by lateral airflow and blow out the front of the unit as aspirate, basically causing all the surfaces in the walk-cooler to become permanently wet. Paper is a most effective collector of this moisture. 

-Causes of this can be:
--Microbial clogging of the drain line. 
--A unit that is out of balance and vibrating excessively (such as a bad fan-motor bearing)
--With volatile acids -  the corrosion of the evaporator coil or the drain pan itself. 
--Other clogging agents. 
--Improperly installed or improperly working cooling fans (erratic icing over as another symptom)
--A drain pan that is not properly leveled to expel excess water or blockage of the drain line for any other reason. 

Other causes:
--Door left open excessively
--Door seals are no longer separating outside (moist) air from inside (cold) air. 

A properly working cooler should not grow mold quickly, I cleaned out a cooler back in 1996 that had papered materials from 1984 stored on its shelf, most items did not have great amounts of mold on them. 

More information about the Methods mailing list