Defrost time

[nike123]

I need to set defrost timer on one walk-in freezer of about 25 m^3. It is very old, and I need to change evaporator.
Load is about 100 kg/day max. fresh food of different kind and usually not packed in plastic boxes or PVC bags that need to be frozen and 200-300 kg stored frozen food.
Evaporator is going to be forced air with electric defrost, and defrost timer is old style wit dial and 15 min division.
What is best setting for this timer and this application by yours experience?

[SteinarN]

I would have tried 3 or 4 defrost a day, 30 or 45 min defrost. Do you have a termostat for defrost stopp?

[nike123]

I would have tried 3 or 4 defrost a day, 30 or 45 min defrost. Do you have a termostat for defrost stopp?

Nope!
Thanks, for your contribution.

At moment it is set at 4 defrost a day (2x15 min and 2x30 min) and it builds up ice.

[SteinarN]

It would be a big advantage with a termostat for defrost stopp. Without a termostat you have to be very careful not to set to long defrost time. And if it is an unusual heave build up of ice, then the defrost time can be to short. If you have a stopp termostat, then you can set a longer defrost time without worrying on overheating the evaporator.

15 min defrost time is very short on a freezer. I will advice to incorporate a defrost stopp termostat and increase the time to 45 min.

[nike123]

It would be a big advantage with a termostat for defrost stopp. Without a termostat you have to be very careful not to set to long defrost time. And if it is an unusual heave build up of ice, then the defrost time can be to short. If you have a stopp termostat, then you can set a longer defrost time without worrying on overheating the evaporator.
That was my worry!



15 min defrost time is very short on a freezer. I will advice to incorporate a defrost stopp termostat and increase the time to 45 min.Ok, I will see what owner is going to say about additional work/parts.
Thanks again.

[Samarjit Sen]

Hi Nike,

Usually 4 defrost a day is adequate. But you should increase the derost time. We use a digital timer wherein we can set time for defrost and also the period for which the defrost has to be done. In a -32 oC Freezer we set the defrost for 30 mnts. Recently I saw the Dixell Cold Room controllers. I presume that they have defrost timers also. They are a bit expensive, but are good. I have to check the catalog and get back to you.

[Samarjit Sen]

Please check the following site
http://www.dixell.com/xlh200300-cool-mate/

[nike123]

Hi Nike,

Usually 4 defrost a day is adequate. But you should increase the derost time. We use a digital timer wherein we can set time for defrost and also the period for which the defrost has to be done. In a -32 oC Freezer we set the defrost for 30 mnts. Recently I saw the Dixell Cold Room controllers. I presume that they have defrost timers also. They are a bit expensive, but are good. I have to check the catalog and get back to you.

No need, thanks. I have Ellywells at stock for that purpose (EWDR 974), but owner don't want to invest any money in that walk-in. He only wants to make it operational again. If one came on to this site, one will probably turn on and run away.:) It is still on R12 and about 25-30 years old, and in poor condition, mainly because snake is in owner pocket.
Thanks anyway.

[philfridge]

I would try 6 defrosts per day for 30 mins

[smpsmp45]

We are using Theben Timers for defrost control. Max time is 30 min for a cycle. But we also sense the Suction temp & beyond the set point the defrost cycle is off. So Max time is 30 Minutes in any case

[Kh1971]

Hi,

I would like to have 3 times defrost in the 24H

Regards

[nike123]

Ok guys, i have got a picture.
I will install defrost end thermostat and try with 4 defrost of 30 min per day.

[SteinarN]

Ok guys, i have got a picture.
I will install defrost end thermostat and try with 4 defrost of 30 min per day.

Are you feeling we are too helpful? :D

[nike123]

Are you feeling we are too helpful? :D

No to helpful:), but if I got few more options, then I will got to pick one, and that will be heavier with that many choices.;)

[paul_h]

It depends on how well the system is set up. How iced up the coils get due to design, and how often the door is open/time door is left open and humidity of product. You may know all this info, you may not.
You'll either have to set and monitor over a few hours, or set and come back to check in a week to see the state of the evap.
Maybe set 4x30min, come back in 3-4 days at about the time a defrost is due, note the coil frost before the defrost, check after defrost if ice is clear. And if you have one, stick a temperature logger in there to see if storage temp is achieved and doesn;t go too high during defrost.