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napter38
23-07-2012, 09:50 AM
We manufactured a refrigerated service case, with an evaporator who has fans. Our customer is using it for selling meat . And refrigerator must work at -3 degrees . And it causes ice on refrigeration. I made natural defrost 10 minutes every hour but it didnot solve the problem. So i used heaters to melt the ice. Do you have any experiences and solutions about this problem. Thamkyou

r.bartlett
23-07-2012, 10:04 AM
If the room is to be -3 how do you expect the ice to melt below freezing/

Yes the evaparator unit should be able to be fitted with heater kit. Contact supplier of evaparator and order it plus you may need new controller/ panel and additional wiring to suit.

r.bartlett
23-07-2012, 10:40 AM
double post...

napter38
23-07-2012, 12:36 PM
it is not a room. it is a refrigerated service case. for selling meat.

Rob White
23-07-2012, 12:43 PM
.

With meat also check the evaporating temperature of the refrigerant.

If it is too low it will cause complications. Normal evaporators
have about a ten degree differance over the coil but if you do
this to fresh meat it can cause the meat to dry out, so the
temp diff needs to be less.

If it is a display case then it will defrost naturaly but if it
is a cold room then it will need heat added to defrost.

If it is a display then set the defrost for about 30 to 40 mins
every four to six hours. But now you have put heaters in they
will require less time.

Regards

Rob

.

napter38
23-07-2012, 02:04 PM
thankyou Rob

Rob White
23-07-2012, 02:36 PM
thankyou Rob

Your welcome.

Oh by the way it is very common for manufacturers to run
meat cases, deli, dairy and such like (air off down to
about -5 deg C) with off cycle defrost and you were correct
in the first but you did not allow enough time for the defros
to happen.

Remember if the coil is iced up as the air flow passes over the
coil and defrosts it the air off the evap is still suficiantly low
so that there is no noticable differance in case temp.

That is why off cycle defrost needs to be for a longer time
and times of 45 mins are not unusual......

Regards

Rob

.

napter38
23-07-2012, 03:40 PM
we were using digital thermostat with one prob. I will change it with the thermostat which has two probs. Refrigerator will make defrost untill evaporator prob temp. is +8 deegrees

Rob White
24-07-2012, 12:28 PM
we were using digital thermostat with one prob. I will change it with the thermostat which has two probs. Refrigerator will make defrost untill evaporator prob temp. is +8 deegrees

Yes, the best way is with two probes.

Regards

Rob

.

Peter_1
24-07-2012, 09:01 PM
Or even better, use hotgas defrost.