Coldroom defrost problems

[weidit]

Hi guys I have not really worked on coldroom freezers before but have a friend with a freezer room in his pub.

Its very old and runs on 404a refrigerant it's runs ok. But seems to ice up a lot. I have found that the system runs all the time. Although seems to reach temp. I think that the defrost isn't working if it has one.

Not working on system like this I want to know what type of defrosts you can use. And where would I look?
The condenser is a Williams and there is nothing written on the evap or control panel.

When would you expect the defrost to kick in? Many thanks

[B G Scott]

Hi guys I have not really worked on coldroom freezers before but have a friend with a freezer room in his pub.

Its very old and runs on 404a refrigerant it's runs ok. But seems to ice up a lot. I have found that the system runs all the time. Although seems to reach temp. I think that the defrost isn't working if it has one.

Not working on system like this I want to know what type of defrosts you can use. And where would I look?
The condenser is a Williams and there is nothing written on the evap or control panel.

When would you expect the defrost to kick in? Many thanks

If it a freezer then it will have defrost cycles.Have a look at the control panel you should find the defrost control in there unless the system is fitted with an electronic controller with a digital readout.
I would think at least 4 defrost in 24 hours would be standard, if it is a site built up unit then it will be electric defrost if it is a one piece package it might be hot gas defrost.
In the first instance try and locate the defrost control and check the operation of the device.
If it is electro-mechanical timer try moving it by hand to see if the defrost stops the Condensing unit and activates the defrost heaters, if it is an electronic control press the defrost button and observe the defrost cycle.

[sedgy]

hi weidit, you say it seams to reach temp < ?< so have you tested the stat, and what is the requiered temp,

[NoNickName]

There may be a fresh air entrainment. I would inspect the seals and the panels for leak tightness

[monkey spanners]

If it is an electronic controller, the evaporator temp probe could be faulty causing it to terminate defrost before the coil is clear. Often you can find out what temp the evap probe thinks the evaporator is by looking it up in the menu in the controller.

[Brian_UK]

"The systems runs all the time"
That shows that it is not running OK.

If it reaches the required set point but doesn't switch off then something is stuck on or not closing.

[NoNickName]

The system runs all the time is not a synonym of the compressor runs all the time.