Freezer Conversion Issues

[jeremy]

Hello,

I am in the process of setting up a chest freezer for kegging. I purchased the freezer, and a Tempmaster from Jaycar, and after some intial problems with my Tempmaster, both the freezer and the controller work fine.

The problem I am having now is that the compressor in the freezer does not switch on straight away when the freezer is switched on. The freezer works well when not plugged into the controller, but when it is switched off, and back on, by either the controller, or manually it does not kick in fast enough. This means it switches on, winds the temperature down to what the controller is set to very quickly, then switches off. When the temperature increases the freezer is switched back on (you can tell by the indicator light), but the compressor takes ages to come on. I assume the freezer has some kind of mechanism in it which prevents it from being flicked on and off all the time, and hence when it is switched off then back on, it waits a while before starting the compressor back up. This makes it basically useless for the purpose of kegging.

Has anyone had this problem with a chest freezer before? Its very frustrating, and its looking like I may not be able to use this setup for the purpose it was bought!! I am even thinking of removing the mechanism within the freezer which cycles it on and off, but not really sure how to do this.

Can anyone help?!? Ive seen that quite a few people have used chest freezers for kegging.

Jeremy.

 

[ant]

I think the compressor delay is a normal and desirable function for the long term availiability of your freezer, but I'm not sure that it's actually a problem. Maybe check with a temp probe what the temperature rise inside the freezer is before the compressor comes back on. If it's a degree or less, which it probably would be because a freezer is well insulated, then I think the setup is still perfect for kegging.

This being said, I'm not a fridgie, nor have I set up a chest freezer for kegging, so these aren't really very "informed" thoughts - take them at your own peril

 

[timmy]

I think the compressor delay is a normal and desirable function for the long term availiability of your freezer, but I'm not sure that it's actually a problem. Maybe check with a temp probe what the temperature rise inside the freezer is before the compressor comes back on. If it's a degree or less, which it probably would be because a freezer is well insulated, then I think the setup is still perfect for kegging.

This being said, I'm not a fridgie, nor have I set up a chest freezer for kegging, so these aren't really very "informed" thoughts - take them at your own peril

How long is the off cycle? Most modern fridges have a solid state start relay and needs a few minutes to cool down or else it just keeps trying to start with only the run windings energised which will keep tripping the thermal overload.

How old is the freezer? Is it electronic or electric controll? Is the controller just cutting the power supply to the freezer or actually wired into the thermostat?

 

[user 384]

A thermostat has a set point and a differential around the setpoint. For example you can set the thermostat to 8C with a 2C differential around the set point so that it turns on when it hits 10C and off at 6C. The range between 6C and 10C is called the hystereis. I have no idea what the hystereis for the Tempmaster is, but if it's too narrow the compressor could cycle on and off too frequently and as you have indicated it seems that your freezer has an anti-short cycle mechanism. This is a good thing!

Don't worry about the compressor not coming on straight away, your beer will still cool down to your setpoint. The thermal mass of 18 litres of beer will also mean that once it has reached the right temp, it will stay fairly stable whilst in the freezer. Even if the the air temp inside the freezer fluctuates a lot more and hence the cycyling on an off, the beer temp will stay fairly stable.

Cheers
MAH

 

[normell]

Hello,

I am in the process of setting up a chest freezer for kegging. I purchased the freezer, and a Tempmaster from Jaycar, and after some intial problems with my Tempmaster, both the freezer and the controller work fine.

The problem I am having now is that the compressor in the freezer does not switch on straight away when the freezer is switched on. The freezer works well when not plugged into the controller, but when it is switched off, and back on, by either the controller, or manually it does not kick in fast enough. This means it switches on, winds the temperature down to what the controller is set to very quickly, then switches off. When the temperature increases the freezer is switched back on (you can tell by the indicator light), but the compressor takes ages to come on. I assume the freezer has some kind of mechanism in it which prevents it from being flicked on and off all the time, and hence when it is switched off then back on, it waits a while before starting the compressor back up. This makes it basically useless for the purpose of kegging.

Has anyone had this problem with a chest freezer before? Its very frustrating, and its looking like I may not be able to use this setup for the purpose it was bought!! I am even thinking of removing the mechanism within the freezer which cycles it on and off, but not really sure how to do this.

Can anyone help?!? Ive seen that quite a few people have used chest freezers for kegging.

Jeremy.

What is the switching range of the jaycar thermostat, and what is the switching amperage of the freezer.
If amps drawn by the freezer are higher than the "Tempmaster", I'd say youre out of luck

 

[timmy]

I remember discussions about the tempmaster, it wasn't to do with the hysteresis but an imbalance in the triac.

i think this is it

 

[normell]

When I had my freezer done, replaced the original thermostat, with a Tobin's TS-040, which has a switching capacity of 16 amps.
Have not had a problem in nearly 12 months, and it keeps kegs around 1-2*C

 

[jeremy]

OK, had a bit of a play and now its working perfectly. I originally had the temperature set to 6 degrees just to test the Tempmaster and the temperature in the freezer would wind down to about 2deg, then over several hours would climb to over 12deg, usually reaching the outside ambient temps overnight!

My first post was a little misleading as I found it a little hard to say what I meant. The Tempmaster iteself was working well, it would switch off a couple of degs below the setpoint, and back on a couple of degs over the setpoint. When it switched on, an indicator light on the freezer showed that the freezer had power to it (ie the tempmaster was working), but for some reason the compressor was obviously not on, and would take several hours to kick in.

Last night I decided I would put the setpoint down a bit lower, to about 1deg which is about where I need it anyway, and now its working a treat. Compressor starts as soon as the tempmaster tells it to. Not exactly sure why, but it may be the freezer just getting settled after being moved in, or the fact that setting it to 1 allows the compressor to run a bit longer to temps closer to what its used to, or any number of different reasons.

Anyway, for the time being it is working great. Such a relief after all the money invested so far. Sorry to waste peoples time by diving onto the site as soon as there was a problem, its just that so many people have done freezer conversions, and nobody seemed to have similar problems to this!

Thanks for the replies, I think the people who suggested that compressor relay is normal gave me the idea that perhaps setting the thing colder may fix the problem. I may yet open my tempmaster back up and widen the hystereis as it is probably keeping the temp a little too close to the setpoint now, but its working so well now I dont really want to mess with it.

Thanks again guys. I am a lot happier today than I was yesterday, now I can concentrate on the more important stuff, like what im gonna fill the thing up with...

Jeremy.