Keg temp?

[kenpotf]

All,

My keezer is set to 36 degrees. I've wondered why my beer seems much warmer than that, so this morning I decided to draw off half a glass of one that's been sitting in there since Thursday. Before I kegged it, it was cold crashing in my fermenter.

Short of it is my keezer is set to 36 degrees with a controller, but the beer is measuring at 51 degrees. Another keg that is in the same keezer is sitting at 46 degrees. What gives? Should I drop my controller down another 10 degrees to see if I can get it colder? My probe is free hanging in the keezer, so I know that's not the best way to measure the liquid, but how can I get a more accurate picture to what the temp is of the actual beer? 36 degree ambient doesn't seem like it's cutting it...

Thanks!

 

[Jordo_nb]

Eventually the temperature inside the keg should match the ambient temp... but you'd think that it would only take a couple days.

Other idea is that possibly your lines are high up in the keezer, while the probe is low. Maybe a small fan to move the air around would help. Does your second glass also taste warm?

 

[Setesh]

Place a small cup of water in your keezer at mid level up the kegs. 4-6 oz only. You could use a box or whatever to reach this level. It doesn't have to be exact, but close to the mid line of the kegs. Let this small glass of water sit for two hours and come back and use a calibrated thermometer to measure the temp of this water. If it is the temp that your controller is set at then your kegs just need more time to equalize. If it is warmer, give it another hour and check again. Repeat until you get pretty stable readings. Remember that your controller has a 'swing' programmed into it. Take this swing into account on your readings on the small cup of water. The kegs won't vary because of their mass, this small cup will change temps very quickly which is why we are using it to test.

The reason to use a small volume of water is that it will equalize in temperature much faster than your kegs. You want it halfway up the kegs to get the average temperature the keg is getting. If the temp ends up being 46 then your controller probe needs to be calibrated, or your keezer needs to be serviced, or you have a leak somewhere letting cold air out/warm air in. What controller are you using? My Johnson was off by 6 degrees out of the box.

Also make sure the thermometer you are using to measure with can be trusted. If your thermometer is adjustable you can calibrate it by following these instructions:
http://www.foodsafety.unl.edu/haccp/helpful/thermcalibration
If it is not adjustable you can at least test to see if it's accurate or not.

 

[kenpotf]

I'm using a thermoworks probe as a thermometer and a johnson controller for control. I'll test this out...how do you calibrate the johnson controller, or is it something that you just adjust for the difference? The one keg that is at 46 degrees has been in the keezer for over a month.

 

[Setesh]

I'm using a thermoworks probe as a thermometer and a johnson controller for control. I'll test this out...how do you calibrate the johnson controller, or is it something that you just adjust for the difference? The one keg that is at 46 degrees has been in the keezer for over a month.

"how do you calibrate the johnson controller"
You can set the offset on the controller itself by going through the menu. The manual should walk you through this. If you don't have your manual do a google search for "Model# of your controller + manual"

"The one keg that is at 46 degrees has been in the keezer for over a month"
Then your keezer either can't keep up, your Johnson is off by ~10 degrees, your thermoworks is off, or some combination thereof. I would start by checking the thermoworks for accuracy, then calibrating your johnson controller. You can use your beer temp as the calibration point, but only after you pull enough to clear the lines and pull fresh beer from inside the keg. Beer from the lines at the top of your keezer will not be the average temp that we want to know.

Does your keezer run non stop? If it is having problems keeping up then it will be running constantly trying to reach the temperature you set. If it is cycling normally the most likely cause of your problem is the uncalibrated Johnson.

 

[kenpotf]

No, it definitely stops. I haven't had the freezer for more than two years. I'll go look at the settings on my controller. This is a new one because I had to replace one, and this one is only about 4 months old. I don't remember the settings that I had set before.

 

[CastleHollow]

In addition to dropping the probe in water, I found that a circulating fan was necessary to keep proper temps. Modify a PC case fan and that might help.

 

[day_trippr]

"how do you calibrate the johnson controller"
You can set the offset on the controller itself by going through the menu. The manual should walk you through this.[...]

fwiw, the Johnson A419 has no documented provision for user adjustable calibration.
The OFS function provides for a switchable temperature "set-back" mode that is quite different from offsetting a probe error...

Cheers!

 

[kenpotf]

There's an offset setting. I can't figure out what this does though. Is this for the "higher" side of the temperature, or does it set the low side? I just put a fan in the keezer to see if it would help a little. I made one for my fermenter, but never put one in the keezer. If this fixes the issue, I'll make another one.

I can set the offset, but I don't know what the difference is. The values are from 0 to 50 degrees, but I don't know if that means that I set my 36 degree setting and the offset means it will add 10 to the 36 or subtract 10 from the 36...does that make sense?

 

[kenpotf]

Update:

I set the thermostat down to 31 with a differential of 2. The glass of water is sitting at 36 degrees. When I use this controller in my fermenter, I tape it to the side of the bucket. Should I tape it to the side of the keg or will that throw off readings? Is there a better way to not read the ambient temp? BTW, the ambient temp isn't really correct either. The Johnson is set to 31, but I have a Taylor thermostat that reads at 36 .... the same temperature as the water temperature that I'm getting from my thermoworks thermometer.

 

[Setesh]

Is there a better way to not read the ambient temp? .

Yes, as mentioned above you can drop that probe in a glass of water and that will help a lot, since the water won't change temps as fast as the air it will help avoid cycling from opening the door. The fan is an excellent idea too and should help quite a bit to even the temperature out top to bottom.

 

[kenpotf]

Is the Johnson probe waterproof, or should I put it in something? Also, I have the fan on the lip of the keezer right now, should i move it to the bottom or leave it where it's at?

 

[Setesh]

Is the Johnson probe waterproof, or should I put it in something? Also, I have the fan on the lip of the keezer right now, should i move it to the bottom or leave it where it's at?

I would check the manual for yours to see if it is waterproof. Or you could mount it in such a way that it doesn't matter. That's what I did. I used a hot nail to poke a hole in the top of an Ozarka water bottle and pushed the probe through enough where only the stainless part was through the lid. The top part where any leak could possibly occur is out of the water. I used hot glue to secure it to the lid so it couldn't slip in or out. It has worked great for me so far, and it doesn't matter if the union is waterproof or not since it's not underwater.

For the fan, mine sits mid level in my keezer where it can get air from the bottom and blow it up to the top, but I don't think it matters really, you just want circulation.

I'll post pics of these when I get home which should be pretty soon.

 

[Setesh]

Here is what I did for the probe. It's hard to tell, but the part where the wire goes into the stainless sleeve is just above the cap here. I used hot glue on the top and bottom of the cap to seal it up and prevent too much evaporation.



And here is my high tech air circulation system

It's just a 120MM computer fan mounted to a box that has holes cut into each side of it and the bottom cut completely out. It pulls air from below and pushes it up. It is wired to a Linksys DC power supply and runs 24/7.

 

[day_trippr]

There's an offset setting. I can't figure out what this does though. Is this for the "higher" side of the temperature, or does it set the low side?[...]

Lots of people have had trouble understanding the OFS function on that controller.

If you take a long look at Table 1 on page 4, however, it should become clear that the OFS function provides a "setback" mode, similar to that found on a domestic HVAC thermostat, with the "spread" between maximum and minimum allowable temperatures increased by 2x the OFS register value.

This means that with OFS enabled the compressor won't kick in until Setpoint + Differential + OFS, and the heater won't kick in until Setpoint - Differential - OFS.

To enable this function you have to wire in an spst switch; without the switch you can set the OFS register to anything you like but it won't do a thing on its on.

Bottom line, it should be evident that the OFS function is not a probe calibration capability...

Cheers!

 

[kenpotf]

Here is what I did for the probe. It's hard to tell, but the part where the wire goes into the stainless sleeve is just above the cap here. I used hot glue on the top and bottom of the cap to seal it up and prevent too much evaporation.
View attachment 183466


And here is my high tech air circulation system
View attachment 183465
It's just a 120MM computer fan mounted to a box that has holes cut into each side of it and the bottom cut completely out. It pulls air from below and pushes it up. It is wired to a Linksys DC power supply and runs 24/7.

Thanks Setesh! I appreciate it. I'm going to look at doing the same thing with my controller now

 

[kenpotf]

Lots of people have had trouble understanding the OFS function on that controller.

If you take a long look at Table 1 on page 4, however, it should become clear that the OFS function provides a "setback" mode, similar to that found on a domestic HVAC thermostat, with the "spread" between maximum and minimum allowable temperatures increased by 2x the OFS register value.

This means that with OFS enabled the compressor won't kick in until Setpoint + Differential + OFS, and the heater won't kick in until Setpoint - Differential - OFS.

To enable this function you have to wire in an spst switch; without the switch you can set the OFS register to anything you like but it won't do a thing on its on.

Bottom line, it should be evident that the OFS function is not a probe calibration capability...

Cheers!

Yeah, that doesn't sound like anything I want....