View Full Version : Reverse fan defrost

24-09-2006, 12:47 PM

Having glycol cooler with separate cooling and heating coils, what do you think to use reverse fan blow for defrosting. Inlet glycol temp -9/-8C.

It is for vegetable cold store temp 0C/70%RH or 4C/85%RH

Best regards, Josip :)

US Iceman
24-09-2006, 03:15 PM
Hi Josip,

I think the lowest coil temperature I would be comfortable with for air defrost would be about -1.6 C (29F). During normal operation at a reasonable load, the coil return bends will frost but the coil face seems to stay wet. As the load decreases the coil face tends to form some light frost which melts relatively quick (at least on refrigerant coils).

In this respect glycol coils may be able to tolerate slightly lower coil temperatures since during defrost the glycol will not evaporate like a common refrigerant (and help to keep the coil cold).

The air defrost would certainly help to maintain the humidity though.