Issue with A419 and consistent temperature

[canihaveurpants]

Two days ago I upgraded to a Johnson A419 digital temperature controller from their analog model hoping for some more consistent fermentation temps but am so far having issues with big temperature swings. My set up as of now is a 7.2 cu ft. Frigidaire chest freezer housing a single 6 gallon Better Boy carboy that had already been fermenting for a week and a half with the analog controller. So even with vigorous fermentation over I am still seeing swings on the temperature display of my Johnson control.
I have the settings as 65 degrees hold, 2 degree variance, and 12 minute cycles. I have been watching and see the temp drop to 60 (while the compressor gets super hot) and then climb all the way back up to 65 within a short period of time (an hour to two) starting the process all over again. Currently I have the probe touching the outside of the carboy covered with bubble wrap. I had previously tried dangling the probe in the air but was having similarly bad results. Anyone have a suggestion? I've read about a million forums on this topic but can't seem to adjust my setup to keep my temp consistent!!

 

[user 4295]

Put the temp probe in a container of water in your freezer.

 

[hulkavitch]

That sounds good but is flawed. You will be measuring the temperature of the water not the fermenting wort. Fermenting yeast produce energy=heat. You need to measure the temperature of the fermenting wort and what you are doing is perfect. Dont know why the swings? But i have a controller on the way for my 7 cf and would like to know the answer.

On a side note there was a guy that did extensive research with thermowells and probes on carboys and he found the temperature only varried by less than half a degree.

 

[canihaveurpants]

hulkavitch,
How tight of a seal does your bubble wrap have over the probe? I have it affixed with 4 pieces of duct tape and it is surely not an air tight seal.
FYI, the last compressor cycle ended at 10:30am this morning reaching a low on the Johnson unit of 60 degrees by 10:40am. It is now 11:40am and the temp on the Johnson control has already risen to 64 degrees, on the cusp of yet another compressor cycle.

 

[sillbeer]

Can you change the range to +/-1?

- Destin

 

[canihaveurpants]

Sillbeer,
Yes I am able to. I figured the compressor would run less if there was more of a gap before it tried to correct the temperature. You would recommend +/-1 ?

 

[sillbeer]

I'm just guessing. My neighbor has one and I plan on buying one soon. My neighbor has no issues with temp flux and I believe he has his set at +/- 2. I'll ask him later when I see him.

Edit: My neighbor has his probe running between the seal on the back side hanging about 2' down inside the freezer. Nothing fancy.

- Destin

 

[DSmith]

Do you circulate air inside the freezer with a PC fan?

Can you put another digital temperature probe under the same bubble wrap and monitor the temperature?

My experience is that a rise of 3F should take 3-6 hours, but that is with the setpoint and ambient temperature about 10F different. I find that the lowest differential results in about a 2F-3F actual temperature swing.

Here's a thread with a graph I made with a datalogger through fermentation that demonstrates the swings:
https://www.homebrewtalk.com/f11/temperature-recorder-338349/

 

[canihaveurpants]

I don't have a pc fan at the moment. Would a 6 inch desk fan do the job? I also don't have a seperate temperature probe at this time but I plan on picking one up this evening to better monitor this siuation.
I set the temp differential to +/-1 degree but looks like I am still on the same compressor time frame as I was earlier.

 

[DSmith]

A 12V PC fan powered by a used cell phone charger is sufficient (I have a 6V power supply). You'll probably not see any difference with a fan so I'd scope out the parts to do the PC way. It just reduces the chance for thermal gradients inside larger freezers. You don't want to create a heat-source as all fans/motors are inefficient, I'd go with a low voltage/low amp fan.

If you mash, think of a digital thermometer purchase that would serve that purpose too. The thermopen is very nice & accurate.
http://www.thermoworks.com/products/thermapen/

This also may be as nice or better:
http://www.thermoworks.com/products/handheld/therma_k.html

 

[hulkavitch]

Sorry about the confusion in my previous post. I was refering to the post about the probe immersed in water. That is a bad idea.

Your method (original poster) sounds very good.

I would duct tape the probe to the carboy and insulate the hell out of it.

Dont know why you are getting the temp shifts. I would also try decreasing the range and see if that does the trick.

 

[hulkavitch]

I dont see how a fan is going to change anything you are looking to measure the temperature of fermentation not the ambient temp of the freezer. And the way you are doing it is the appropriate method. Jamil and John P. agree. There is a whole podcast on temperature control on the brewing network. And they suggest a fridge with the controller attached to the carboy and insulated.

Can you contact johnson?

 

[sillbeer]

I Just talked to my neighbor. His chest freezer is really old. He has his setup for +/-2 degrees and has never had an issue.

- Destin

 

[DSmith]

I Just talked to my neighbor. His chest freezer is really old. He has his setup for +/-2 degrees and has never had an issue.

- Destin

How do you define "issue"? Without constant monitoring, how do you ever know if the temperature fluctuates a few degrees? My guess is that people just set the values and assume that's what they get.

Incorporating a fan may just reduce the amount of time the freezer is on because the cold air will be forced to flow around the fermenter. Agreed it has little relevance to this tread. It may help if a degree if undershooting the setpoint-differential.

 

[canihaveurpants]

A buddy of mine has a thermometer with wired probe that he is letting me borrow when I get out of work. I will report back about the range of temp between my Johnson control and thermometer.
I have added more pieces of duct tape to better insulate the probe against the fermenter wall but so far it doesn't seem to have made much difference. I'm only working 4pm-8pm today so I will investigate more this evening.
Thank you everyone for the suggestions and information so far.

 

[Copbrew133]

I have heard people talk down on using a stopper thermowell to monitor the fermenting temp of the wort, but I like it. Granted there were a few issues at first. The rubber stopper the well came in sucked. I solved it by removing the thermowell from the stopper and now use it in one of the holes of a carboy cap. Use the other hole for the airlock or blow off. Only issue now is when first putting the carboy full of wort into the ferm. chamber. If the wort is a few degrees above the set point on the A419 the freezer will run until freezing prior to the wort cooling to whatever the set point is. This was easily solved though by monitoring the wort temp and just dangling the temp. probe from the controller in air at what my fermenting temp is going to be. Once the freezer and wort are stabilized at the same temp. I put the probe into the thermowell and it's good to go. I have found the freezer doesn't cycle very often at all and the fermenting wort stays a consistent temp and no wild temp swings.

 

[sillbeer]

How do you define "issue"? Without constant monitoring, how do you ever know if the temperature fluctuates a few degrees? My guess is that people just set the values and assume that's what they get.

Incorporating a fan may just reduce the amount of time the freezer is on because the cold air will be forced to flow around the fermenter. Agreed it has little relevance to this tread. It may help if a degree if undershooting the setpoint-differential.

He's never had a bad batch.

- Destin

 

[hulkavitch]

I have heard people talk down on using a stopper thermowell to monitor the fermenting temp of the wort, but I like it. .

I am by no means talking it down. I just think it is an unecessary costly piece of equipment, since studies have shown that a probe in the center of the wort and one on the side of the carboy have a variance of .5 degrees or less.

 

[Copbrew133]

I get what your saying, its just my preference. As far as equipment goes its not much money for the setup I use. I had some of these same issues with temperature variance until I got this thermowell system down. I wasn't too keen on having something in the wort at first, but I sanitize the piss out of the stainless tube and havent had any issues. So often as it is in brewing it falls back to the old saying that there is more than one way to skin a cat.

 

[Mpavlik22]

I am by no means talking it down. I just think it is an unecessary costly piece of equipment, since studies have shown that a probe in the center of the wort and one on the side of the carboy have a variance of .5 degrees or less.

Which studies? According to the new article in brew your own magazine by Chris bible it could be a several degree difference from the middle to outside wall of the fermenter...

 

[hulkavitch]

Which studies? According to the new article in brew your own magazine by Chris bible it could be a several degree difference from the middle to outside wall of the fermenter...

Podcast: brewing network presents fermentation control by jamil z. and J. palmer sites what i think is the same article saying the differnce is minimal even as little as .5 degree.

 

[hulkavitch]

Actually the article you are refering to is probably a newer one since the podcast was in '09. I dont know how statistical data changes...unless of course the new study was sponsored by the makers of thermowell.

 

[Mpavlik22]

Actually the article you are refering to is probably a newer one since the podcast was in '09. I dont know how statistical data changes...unless of course the new study was sponsored by the makers of thermowell.

Me either. Wasn't sponsored by any company.

 

[canihaveurpants]

So I set up a separate thermometer which is showing a constant 4 degree difference than the display of the Johnson controller. A compressor cycle just ran leaving the thermometer to read 58 degrees and the Johnson to read 62. This is much lower than I would like (having the Johnson set to hold 66 degrees). I am thinking I will set the Johnson to 70 degrees (actually 66 according to the thermometer) with +/- 1 and monitor the two temps. I am thinking my Johnson controller is unfortunately overshooting the actual temperature.

 

[canihaveurpants]

Also hoping my Two Hearted clone that is being subjected to these temperature swings isn't going to be too negatively affected!

 

[hulkavitch]

So is your controller faulty or do they all do this?

 

[BrasseurGeorges]

Problem is the amount of time the ambient temperature takes to cool the beer. By then the air around it is very cold. It stays cold, continues to cool the beer, so you end up down around 60F even though you only wanted 65.

Set the differential down to 1 degree. That way the temp swing is recognized more quickly and gives it less to deal with. The 12 minute cycle delay will protect you from cycling the compressor too often.

Try less bubble wrap, again, in the interest of it not dropping the ambient temp too low.

Open the unit up and set the jumpers so the target temp is floor, not ceiling. At least that's what I prefer. So, it cools down to your target temp, not starts cooling at the temp you set.

It's also nice to have a stopper thermowell with a panel mount (or otherwise) probe thermometer in there to monitor internal temp. Run your own tests, see what works for you.

All this coming from a guy that's plugging and unplugging a little heater inside a chest freezer to keep a couple Saisons up to 80F... I needs me a Ranco and Fermwrap.

 

[DSmith]

Here's a fermentation with the A419 and chest freezer. The 1F differential results in about 2.5F temperature swings.

The freezer ran every 4 hours during active fermentation and about every 9 hours later. The ambient was 70F-72F, bigger differences between ambient and set-point would shorten the time between cycles.

I also like to set the controller to cut-out-at-set-point to know the coldest the fermenter will get, or the hottest in heating mode.

Temperature control is only one aspect of brewing. I haven't found these swings to negatively affect attenuation or flavor. I plan of the temperature rise and set the controller 1F-2F lower than the intended fermentation temperature.

 

[Buna_Bere]

Here's a fermentation with the A419 and chest freezer. The 1F differential results in about 2.5F temperature swings.

Thanks for posting this graph, it's nice to see some real data. I've done similar experiments, unfortunately without your sweet temperature logging setup. It's interesting that when your freezer cuts out at 65 after it's been running, the wort temp only drops from 67-67.5 or so to 65. When I've tried this with the probe insulated to the side, the wort temp would drop alot lower then just the 2-2.5 degree drop you've measured. Your graph really shows the air temp overshoot to the cold side very nicely.
I found that you can reduce the 2-2.5 degree wort temperature swings to practically 0 by keeping the probe in the air. I keep the probe about a foot from the bottom of the freezer and a couple inches off the side wall. I also keep a seperate temp probe insulated and taped to the side of the wort just to monitor the wort temps.
I manually lower the temp on the controller by 1-3 degrees when I see the fermenting wort temp starting to rise. This keeps the wort temps much more stable, avoiding the 2-2.5 degree temperature swings on every on-off cycle.
Dsmith if you have the time and can repeat the temp logging with a probe in the open air, I think you'll see the wort temp remains more stable.

The following here is a little rant on the BYO article on temp control, I like BYO alot, but I thought this article was lacking.
I've read the temperature control article in the July-August BYO and the graphed data they show in there is severely lacking. For example the graph on page 62 Fig 1 only shows the wort temperature dropping until it hits the set point of 65 and then no more data. The point of even graphing this is to see the stability of the wort temp after the wort temp has stabilized, and they show no data.
Now look at figure 2 on page 63, the wort temp stabilizes at around the 38 mark and remains almost perfectly flat until the 60 minute mark when they stop the data. Why is the freezer or fridge cycling on and off every 5 minutes or so when the probe is in the stable wort? look at the 45 minute mark, the 50 minute mark, and the 55 minute mark, the freezer or fridge is clearly cycling on here, but the wort temp hasn't moved, what triggered the fridge or freezer to cycle here? I thought the controlling probe was in the wort? maybe the temperature probes they used in their experiment weren't very accurate.

Thanks again Dsmith for posting this graph, it's much more useful than the 1 hour graphs of wort temps dropping they put together in BYO.

 

[canihaveurpants]

So after not seeing any improvements with my manipulation of the probe insulated against the carboy I decided to tape the probes (uninsulated) against the side of the chest freezer a few inches from the bottom. I realize this method won't be the most accurate for exact fermenting wort temperature but so far it has been keeping much more stable.
I plan on insulating the temperature probe against the carboy while keeping the Johnson probe taped against the chest freezer wall. This way I will have a reading of wort temperature while being able to reduce compressor cycles with a more steady temperature controller reading. There still exists a 3-4 degree difference between the two displays taped against the freezer wall but I can take that into consideration when setting the Johnson settings.