Chest Freezer & Tempmate

[Budron]

Hi guys,

I have an old chest freezer that I put a collar and top on.
I'm using the TempMate from Ross and it's all working fine.

The only problem is, the temp seems to raise about 0.2c every 10 mins and the compressor kicks back in about every 1.5 hours.
Is this normal, or am I losing cold are from somewhere?
Haven't dealt with a temp controller before so dont really know what to expect.
How often does your compressor turn on?

Cheers,

Budron.

EDIT: Got my temp set to 5 degrees and difference setting of 2 degrees.

 

[chappo1970]

Depends on the tollerance setting and the time of year. Generally on the ferment fridge I have it set to 0.5 degrees +/- and in winter lucky if it runs in summer however it will flick on and off regularly say every 1/2hr or so? Sounds like you may have a leak of some sorts or maybe the fridge seals aren't the best?

Cheers


Chappo

 

[QldKev]

What's in the chest feezer at the time

Fermenting generates heat,
have you added a keg that is warmer than the set temp

May have to watch my fridge tonight to see what it changes.. Never really paid much attention to it.

QldKev

 

[Budron]

Nah nothing's in it as yet, will be putting a warm keg of beer in it to chill down this afternoon though.

I forgot to mention. I am using a coffin box style thing on the lid, which I have insulated. I have 2 holes about 2".
I was going to install a pc fan to suck air up into the box, because I just presumed that all the cold air in the freezer would sink, but maybe the cold air is already heading up there and escaping from somewhere?

 

[Supra-Jim]

By my simple maths, your temp rise of 0.2degC every ten minutes, means you'll hit your pre-set temp differential after 100mins. This is just over 1.5 hours (1.67 to be more precise), and is inline with what your saying is happening.

If you want to extend the time between startups, possibly look at insulating the back of your collar (if you haven't already), and check the health of your seals.

Cold air will not rise naturally up into your coffin box, hot air rises, cold air sinks. To get cold air up you need a fan to push or suck it up, however you also need a means by which the air can return back down, otherwise the fan will do nothing, as they don't work across large pressure differences.

Also pushing your cold air up into the coffin box will most likely increase the temp increases your experiencing, as this is probably not as well insulated as the freezer body. Plus the taps will act as heat sinks (i.e. your cold air will cool them, warm ambient air will warm then, the net result being heat energy added to your cold environment).

Cheers SJ

 

[Budron]

By my simple maths, your temp rise of 0.2degC every ten minutes, means you'll hit your pre-set temp differential after 100mins. This is just over 1.5 hours (1.67 to be more precise), and is inline with what your saying is happening.

Yeah, that's how i worked it out.

If you want to extend the time between startups, possibly look at insulating the back of your collar (if you haven't already), and check the health of your seals.

The timber I used for the collar is about 40mm thick. Is it common practise insulating the collar, as cold are sinks anyway?

Cold air will not rise naturally up into your coffin box, hot air rises, cold air sinks. To get cold air up you need a fan to push or suck it up, however you also need a means by which the air can return back down, otherwise the fan will do nothing, as they don't work across large pressure differences.

I have 2 holes for the coffin box. A fan will sit under 1 and suck air up to it. The other is there to let the air go back down and circulate. Will this not work without another fan to push the air back down the other hole?

Also pushing your cold air up into the coffin box will most likely increase the temp increases your experiencing, as this is probably not as well insulated as the freezer body. Plus the taps will act as heat sinks (i.e. your cold air will cool them, warm ambient air will warm then, the net result being heat energy added to your cold environment).

I haven't got the fan system running yet, so it wouldn't explain the problem at the moment

 

[Supra-Jim]

Two holes in your coffin box sounds good. You shouldn't need a second fan. I realise you don't have the fan running air up into the box yet, but just commenting that once you start doing this, you'll be adding heat to your system.

I have plans to build one soon (i has the freezer by cabinet maker friend is busy!!!) and regardless of the thickness of the collar, I'll be putting some insulation on the back side of it. Can't have too much i reckon!! Cold air does sink, but if your collar is well insulated then you'll get a more even temp across the whole freezer.

Wood is typically a poor conductor of heat, but it doesn't hurt to help the matter with a little insulation.

Cheers SJ

 

[Offline]

Nah nothing's in it as yet, will be putting a warm keg of beer in it to chill down this afternoon though.
.....

with nothing in it you have a small thermal mass (just the air) so it will cool down and warm back up quickly in comparison to a large thermal mass eg. 4 full kegs = 80 litres of mostly water

 

[Supra-Jim]

with nothing in it you have a small thermal mass (just the air) so it will cool down and warm back up quickly in comparison to a large thermal mass eg. 4 full kegs = 80 litres of mostly water

Aha! the man makes a very good point. Larger thermal mass will take longer to change temp.

Cheers Sj

 

[Budron]

Thanks for all the replies guys!

Will see if a few full kegs in the freezer make a difference, and I might run down the hardware shop for some insulation for the collar. Any recommendations on what to use?

 

[chadjaja]

Cold keeps cold cold.

Even then I have a brand new freezer with no collar on it yet it turns on every hour or so in a cold garage.

 

[Budron]

Thanks chadjaja, was the info i'm looking for. I thought I was just being paranoid about the (slowly) rising temp

 

[macmac]

Is your temperature probe in liquid or in the air? When i was researching my freezer setup, i noticed quite a few people have a jug of water or whatever and keep their temp probe in the water.

The reasoning behind it was that the water would warm slower than the ambient temperature inside the freezer, meaning your freezer would run less.

 

[Budron]

Good point macmac.
I currently just have it hanging in the air.

I remember reading somewhere that the Tempmate's stock probe isn't meant for liquid.
Would I have to buy a submersible one?

 

[macmac]

Good point macmac.
I currently just have it hanging in the air.

I remember reading somewhere that the Tempmate's stock probe isn't meant for liquid.
Would I have to buy a submersible one?

Not 100% sure mate.
I dont have a tempmate, i have a DEI 105A that i got from my LHBS pre-wired. The probe looked good enough to me, so i put it into a tallie full of water in the bottom of the freezer.
If you're really worried, i reckon you could wrap your probe in some gladwrap to seal it up then chuck it in.

 

[watchUburn]

I just stick mine under the fermenter.

 

[chadjaja]

Do what I said earlier. I got one of those $2 blue ice gel packs from a $2 shop that I use for sporting injuries. Cut it open and pour it into a glass. Place the glass in the freezer and insert the probe. I use the standard probe and haven't got any rust issues and it works perfectly. The freezer doesn't cycle so often as it would with it just dangling in the air even with a pc fan in there as well.

Of course with the amount of liquid in the kegs their temp sways a lot less than the temp glass and remains pretty stable.