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cadwaladr
23-02-2015, 07:55 PM
I look after a cold store seven by seven by four metres high,all works well two condensing units two evaps sometimes the evap fans build up with ice,drains and defrost all working I was thinking of putting heater tapes around the circumference of the fan guards good or bad idea?,freezer runs at minus twenty five c.

monkey spanners
23-02-2015, 09:15 PM
Installed a couple of evaps in a similar sized room and the fan apertures actually had peripheral heaters on them from the factory. They work well enough to give you a nice burn haha

Grizzly
23-02-2015, 10:12 PM
I look after a cold store seven by seven by four metres high,all works well two condensing units two evaps sometimes the evap fans build up with ice,drains and defrost all working I was thinking of putting heater tapes around the circumference of the fan guards good or bad idea?,freezer runs at minus twenty five c.

Hi cadwaladr.
Peripheral heaters are a good option.
Historically during my resident Cold Store Engineer days. It was not unknown for a Evap fan blade which had stopped rotating and was in a vertical position. To trip it's 3 phase motor protector.
Meaning that when on defrost a fan blade which is vertical can have the ice from around it start to melt.
The water from this then runs down the pitched blade bridging the gap between blade and fan cowl.
This then it turn freezes during drain down and when the fan motor tries to start It's Tripped.
Ice build up around the periphery of the fan is an even more common issue as I am sure many here deal with.
So Yes a peripheral heater is a good option.
But it's all dependant upon size / heat output as I am sure someone can explain better than me.
Grizzly

al
23-02-2015, 11:55 PM
Socks work well too instead of heaters, on defrost they flop down and trap heat in coil, i think gunther coolers come with friperal heaters

sterl
24-02-2015, 12:20 AM
These are electric defrost coils, correct? Often the moisture travel occurs where the air inside the casing and the metal of the coil getting way hot; which drives the moisture transfer as convection....

While controls can't guarantee everything, you might take a minute to study this: We have had success addressing the conditions you are encountering, by turning down the effective rate of heating....That is cutting off the electric heat once the row third from the bottom reaches about 9 to 10-deg. C. These will do that; as will some others. The controller is also web-addressable...the particular owner wanted that badly but we found almost as much advantage in the efficient and effective defrost as well as acting as controller for the EEV's.
http://ke2therm.com/files/Theory_T-1-1_August_2012.pdf

coolhibby1875
24-02-2015, 06:55 PM
Hello are these coolers searle is range?

chemi-cool
24-02-2015, 09:06 PM
I look after a cold store seven by seven by four metres high,all works well two condensing units two evaps sometimes the evap fans build up with ice,drains and defrost all working I was thinking of putting heater tapes around the circumference of the fan guards good or bad idea?,freezer runs at minus twenty five c.

If ice builds up and stop the fans or does not defrost, peripheral heaters are the best solution.
Most manufacturers supply them as an option.
heating tape 40W\m will do the job well but they have to be energised all the time.

PaulZ
26-02-2015, 05:17 AM
Hi Cadwaladr
I tend to agree with sterl.
I know when we do hot gas defrosting we try and keep it as short as possible and have the gas as cool as possible, this helps to reduce the amount of moisture coming off the coil. I suppose the same applies to electric defrosting.
We have installed heater tape around the fan casings but this was a last resort as they have to be left on as stated by chemi.
Regards
Paul