Chest freezer can't keep up

I think my chest freezer is dying.

Is it plausible that fermentation is really generating enough heat to out-compete the compressor? Or is my freezer dying? I'm thinking the latter.

A freezer designed to keep things sub-zero should be able keep an ale at 67°...

Have it set to 67°, it can't get beer temp below 71°
Other liquids in freezer are 61°

6g of 1.060 wort actively fermenting
Healthy, active pitch of 2565 Kölsch plus 60s O2

Probe taped to side of carboy, insulated. Confirmed temps w/Thermapen.

Frigidaire FFC09C3AW1 - 9.0 cuft
DIY EBay temp controller build
~80 degree ambient in garage

Try setting the controller temperature lower and if the beer temperature drops then the freezer is working.

Worth giving a shot...how do you think that'll help?

It's set at 67° and the probe is reading 71°, so the circuit is "on".... So if I set it lower, the circuit will still be on, right? So what will that change?

First check to see if the compressor is running (it will vibrate slightly), if it is running, check that the coils on the back or that the outside of the back of the fridge is warm ( the condenser coils are on the outer side of the skin so you should be able to feel some warmth). If that is all good, feel the inside walls of the freezer. You should be able to feel the cold.

There really isn't much to refrigerant circuits, if the comp is working and there are no leaks, it should cool. If a minor leak exists, you could need a recharge of the coolant in the system. Or the compressor could just be dead.

How does the controller work? Is it a temperature switch, or a PID? If it is anything but a simple temp switch, the coefficients may need adjustment to keep up with warmth being produced inthe chamber.

Compresser: running
Back: warm
Inside walls: Cold; ice forms in spots
Controller: Simple switch; on/off

It just seems like it's not strong enough, which makes me think low on coolant. From what I've read, that's not something I can DIY refill myself.

Could it be something with the internal thermostat on the chest freezer?...I have it turned all the way to "coldest", but wondering if somehow it's regulating itself?

so, does it run continuously then? if the probe is reading 71 and the sp is 67 it should be on 24/7, unless the compressor gets too hot and it shuts down to protect itself.

if ice forms I'd say your freezer is working fine.

If ice is forming and all those other points are working, I would say it is working fine. What hysteresis do you have set on the controller? Maybe your temperature band is too wide???

Alternatively, what stage of fermentation is going on? Maybe the beer temp. is ramping exponentially? If that is the case, when you get home today it might have leveled off and be maintaining the desired temp.

oh, right, what's the deadband? if its set to 4F then it's working perfectly.

To me, it makes sense that the fermentation would generate the heat.

Your freezer could be at 67*, but your fermenting beer could be 71*.

What is the external temperature where you are at?

I've been in a similar situation since day one of controlling temps in my chest freezer: the temperature maintained by the probe is consistently 10 degrees warmer than my johnson controller set point. My freezer works perfectly, the issue is my controller. However, armed with what I need to do to achieve the target fermenting beer temperature, I just compensate with the controller. So should you, I suppose...

Plus 1 on what he said^^^^ set the temp a little cooler, and narrow your range to 2 degrees and see if that doesnt resolve the difference. 67 degree set point and a 71 degree temp looks like a calibration error possibly in the sensor circuit. If using K-Type thermocouples the cold junction monitor may be compromised or missing too.
Bob

bigbeergeek said:

I've been in a similar situation since day one of controlling temps in my chest freezer: the temperature maintained by the probe is consistently 10 degrees warmer than my johnson controller set point. My freezer works perfectly, the issue is my controller. However, armed with what I need to do to achieve the target fermenting beer temperature, I just compensate with the controller. So should you, I suppose...

Click to expand...

well, i'd ask you the same question, what's the deadband set to?

Good comments, thank you.

motobrewer said:

so, does it run continuously then? if the probe is reading 71 and the sp is 67 it should be on 24/7, unless the compressor gets too hot and it shuts down to protect itself.

if ice forms I'd say your freezer is working fine.

Click to expand...

Temp band is 0.5°C, so yes, it's been on 24/7. I'm wondering the same about the compressor shutting itself off, even though power is supplied to the unit via controller.

Ice is forming, but the unit isn't cooling the beer, hence saying it "can't keep up". I'm just having a hard time believing that deep-freeze chest freezer can't reduce 5g of beer from 71 to 67...even during active fermentation. But maybe the warmer pitch accelerated growth and got out of hand quickly.

So, is it plausible that fermentation is really generating enough heat to out-compete the cooling power of the freezer? I have no idea how "powerfully" these things can cool...

I mean, I just lagered for 2 months at 34 degrees with no problem, but there was no fermentation heat being generated.

With this, I'm currently in the most active part of fermentation.



Thank you all again for thinking about this.

Rbeckett said:

Plus 1 on what he said^^^^ set the temp a little cooler, and narrow your range to 2 degrees and see if that doesnt resolve the difference. 67 degree set point and a 71 degree temp looks like a calibration error possibly in the sensor circuit.

Click to expand...

Range is 0.5 degrees and controller is properly applying power to the freezer...it's as if the freezer were plugged into the wall.

TyTanium said:

Good comments, thank you.



Temp band is 0.5°C, so yes, it's been on 24/7. I'm wondering the same about the compressor shutting itself off, even though power is supplied to the unit via controller.

Ice is forming, but the unit isn't cooling the beer, hence saying it "can't keep up". I'm just having a hard time believing that deep-freeze chest freezer can't reduce 5g of beer from 71 to 67...even during active fermentation. But maybe the warmer pitch accelerated growth and got out of hand quickly.

So, is it plausible that fermentation is really generating enough heat to out-compete the cooling power of the freezer? I have no idea how "powerfully" these things can cool...

I mean, I just lagered for 2 months at 34 degrees with no problem, but there was no fermentation heat being generated.

With this, I'm currently in the most active part of fermentation.



Thank you all again for thinking about this.

Click to expand...

That is strange. on the surface i'd say if its running 24/7 then your freezer is done. but if ice is also forming it's obviously getting lower than 32F on the walls.....

I would sit next to it for a good hour to ensure it is running constantly. If that's the case, and its not getting below 65F, it's probaby got a leak.

Low on refigerant will cause the compressor to thermal cycle while still cooling enough to form frost and ice. If the compressor shuts off, unplug it and place a hand on the compressor, if it is too hot to rest a hand on for 10 seconds your probably low on gas. A fridge guy can fix that, but then it has to go to the shop to get it done and that means ya gotta empty it out.
Wheelchair Bob

Yeah, low refrigerant can cause the evaporator to run colder than normal (pressure / temperature relationship thing) which will cause air with moisture to freeze on the coil (or inside freezer wall in this case). BUT, since it's low on refrigerant, it doesn't have the capacity to transfer the amount of heat that it normally would so the controller won't be satisfied and keep the compressor running - possibly nearly continuously.

Just out of curiosity, have you considered putting a small fan (like a computer fan) in there to move the air around. Moving air will likely help the heat exchange from your fermenter to the surrounding air, as well as from the icy cold sidewalls to the air.
I have a small fan running in mine 24\7 and in a 15cu ft freezer it manages to keep temp just fine even with 5 carboys in primary fermentation bubbling like crazy.

Interesting. Sounds like low refrigerant then. It's a pretty old freezer. From what I've read, refilling it is pretty expensive, right? Might be cheaper to get a new one on CL (bummer).

krazydave - I've not considered a fan, never needed it before...may be a good bandaid solution, though.

Update: Now that fermentation has slowed, it has no problem keeping a constant 67°

sounds like a leak. fixing it is generally more expensive than replacing.

at least you got some use out of it. i bought a big 6.5' long chest freezer off CL. when i bought it I plugged it in, compressor kicked on fine. figured it was good. got it home, plugged it in. wouldn't get below 55F.

motobrewer said:

sounds like a leak. fixing it is generally more expensive than replacing.

at least you got some use out of it. i bought a big 6.5' long chest freezer off CL. when i bought it I plugged it in, compressor kicked on fine. figured it was good. got it home, plugged it in. wouldn't get below 55F.

Click to expand...

Haha, yeah I read that thread! Major bummer. That's what made me think it may be low and/or a leak.

i had a thread about it?!?!?

This one:

https://www.homebrewtalk.com/f35/used-chest-freezer-not-cooling-152283/

lol, well, look at that!

For what it is worth, after running an old CL fridge for a long time as my keezer, I would suggest saving pennies and buying a new freezer. At the very least only buy a newer used one that is efficient. The energy difference between older fridges and newer models is staggering. You will make up the price difference in half a year. After turning off my keezer for the last time, our monthly energy bill dropped considerably (I want to say on the order of $50).

Just something to consider.

Boerderij_Kabouter said:

For what it is worth, after running an old CL fridge for a long time as my keezer, I would suggest saving pennies and buying a new freezer. At the very least only buy a newer used one that is efficient. The energy difference between older fridges and newer models is staggering. You will make up the price difference in half a year. After turning off my keezer for the last time, our monthly energy bill dropped considerably (I want to say on the order of $50).

Just something to consider.

Click to expand...

Very excellent point. Time to build a spreadsheet optimization model.

Boerderij_Kabouter said:

For what it is worth, after running an old CL fridge for a long time as my keezer, I would suggest saving pennies and buying a new freezer. At the very least only buy a newer used one that is efficient. The energy difference between older fridges and newer models is staggering. You will make up the price difference in half a year. After turning off my keezer for the last time, our monthly energy bill dropped considerably (I want to say on the order of $50).

Just something to consider.

Click to expand...

wow, that's insane. $50 would be a bigger portion of my electric bill, and the entire portion in shoulder seasons.

multi-post

multi-post

Yeah it was a really old junker, but I was still shocked. That is about 10x more expensive to operate than a new fridge. Full cost recovery within one year.

TyTanium said:

Worth giving a shot...how do you think that'll help?

It's set at 67° and the probe is reading 71°, so the circuit is "on".... So if I set it lower, the circuit will still be on, right? So what will that change?

Click to expand...

I misunderstood that it was still running at your set point. Sounds like you have it figured out as being low on freon.

I recently bought a brand new freezer to replace a dead one.

I've been pretty vigilant on craigslist and have found newer 12-14 cubic foot chest freezers for $100 or less but I generally only get 2-4 years of use out of them.

Boerderij_Kabouter said:

[...]The energy difference between older fridges and newer models is staggering. You will make up the price difference in half a year. After turning off my keezer for the last time, our monthly energy bill dropped considerably (I want to say on the order of $50).

Just something to consider.

Click to expand...

+1

~25 years ago when my sons were just a few years old and already starting to consume a grocery store worth of food every week, the spousal unit and I decided to spring for a large freezer and buy in bulk. The amount of energy that sucker consumed matched the kids appetites - the cost was around $25 a month for the damned beast. As soon as the kids were off to college we got some poor bastid to take it off our hands for free.

A couple of years ago I picked up a two year old 10cf freezer to turn into a six faucet keezer. Without using a Kill-o-watt on it I have no idea how much energy it uses in keezer service, but it's barely making a blip on our electric bill.

Indeed, since replacing most of the incandescent lights in the house with CFLs, our bill has been running 15-20% lower month-to-month for the last couple of years - and that's with not only the keezer, but a pair of 17cf fermentation fridges as well. All three units are e-Star rated, and these new-era chillers are amazingly efficient...

Cheers!

Alright, I'm convinced. Thanks for the fantastic information guys. Saving up for a new, efficient freezer. Mine's in my garage...hot & humid in the summer. Efficiency matters.

Well, I lucked out, big time. Got one for $80 on Craigslist that is also new(ish) and EnergyStar rated. Found, emailed and picked up same day, and was only 15mins away, awesome. I'm pumped.

Maytag 14.8 CuFt


Footprint (from HBT sizing chest freezer thread):


Power consumption at 0°F is ~350kwH annually, roughly $30. Thinking it'll use less at 34°F - 70°F.

Thanks for all your comments!