True tdd-1 ideal temp controller settings

[kupermanp]

Hi,

I have a tdd-1 kegerator that I bought used. The thermostat was broken (always on) so I installed a Docooler temp controller (basically the Fahrenheit version of an stc-1000). My question is what compressor run time should I be shooting for. I assume a few longer runs is better than a bunch of short on and off cycles, but I'm sure there is a point of diminishing return.

Right now its set for 35F and the default temp range which gives a 20min run time every hour or so (20min on / 40 off).

Thanks
Paul

[PointPleasantNJBeerguy]

Stupid question but why didn't you just replace with the proper Tsat to eliminate issues...? They are easy enough to install.

[kupermanp]

Good question. I wanted a accurate digital readout that I could see without opening the door. The separate temperature probe lets me attach it to the keg so I can get a better idea of the beer temp vs air temp. It was also cheaper ($17 controller and $8 worth of wire) and I can easily convert it to a fermentor if I ever needed to.

[KillianBoy]

kupermanp,
I agree with PointPleasantNJBeerguy, maybe you should just replace, thermostat has several parts to it, one part maybe bad but IF NOT bad, until you make sure, ETC may not work properly.
Commercial units (like True) are pretty rugged and meant to have a frequent on and off cycle, 20 on and 40 off is a pretty extreme off cycle. The best way to check how unit will chill beer is 5 gallon bucket and regulator thermometer method and WAIT and see, it takes a while to figure what is happening, maybe a few days.
KB

[kupermanp]

kupermanp,
I agree with PointPleasantNJBeerguy, maybe you should just replace, thermostat has several parts to it, one part maybe bad but IF NOT bad, until you make sure, ETC may not work properly.
Commercial units (like True) are pretty rugged and meant to have a frequent on and off cycle, 20 on and 40 off is a pretty extreme off cycle. The best way to check how unit will chill beer is 5 gallon bucket and regulator thermometer method and WAIT and see, it takes a while to figure what is happening, maybe a few days.
KB

Thanks. I was planning on eventually replacing the thermostat as part of my general OCD. I have no doubt the unit will chill beer fine. When I first turned it on it froze a gallon of water overnight (which is how I discovered the thermostat was always on).

One of the nice things about the controller is you can set a lot of parameters ( set temp, what temp turns the compressor on and at what temp to turn off etc) and I was trying to get an idea of what type of compressor run times I should be shooting for. I was planning on using the 5 gal bucket thing to calibrate the controller so my set temp represents the beer temp. The longer off cycle may be due to the fact that its currently in the garage right now which is currently very cold

K

[THE ICEMAN]

Thanks. I was planning on eventually replacing the thermostat as part of my general OCD. I have no doubt the unit will chill beer fine. When I first turned it on it froze a gallon of water overnight (which is how I discovered the thermostat was always on).

One of the nice things about the controller is you can set a lot of parameters ( set temp, what temp turns the compressor on and at what temp to turn off etc) and I was trying to get an idea of what type of compressor run times I should be shooting for. I was planning on using the 5 gal bucket thing to calibrate the controller so my set temp represents the beer temp. The longer off cycle may be due to the fact that its currently in the garage right now which is currently very cold

K

The aftermarket temp controller is obviously not what the manufacturer called for but that does not mean it will not work. I have a Ranco ETC on my custom built & it works fine. As you said, it allows you to adjust the parameters. I would recommend that you place the temp sensor near the incoming air (the fan) of the evaporator to give you a more accurate idea of the box temp.
I would not worry about the 20min on/40min off. If it were the other way around, then there is cause to worry. Typical run time for those units would be something more like 15 on/15 off, give or take. The reason for the cycle times you are experiencing could be the differential you have set into the controller, that & the cold weather. A typical differential for the on/off temps would be 3 to 4 degrees.


THE ICEMAN

[kupermanp]

The aftermarket temp controller is obviously not what the manufacturer called for but that does not mean it will not work. I have a Ranco ETC on my custom built & it works fine. As you said, it allows you to adjust the parameters. I would recommend that you place the temp sensor near the incoming air (the fan) of the evaporator to give you a more accurate idea of the box temp.
I would not worry about the 20min on/40min off. If it were the other way around, then there is cause to worry. Typical run time for those units would be something more like 15 on/15 off, give or take. The reason for the cycle times you are experiencing could be the differential you have set into the controller, that & the cold weather. A typical differential for the on/off temps would be 3 to 4 degrees.


THE ICEMAN

Thanks thats what I was looking for. My understanding is if you attach the probe to the keg or put it in a volume of water you should narrow the on off differential to adjust for the larger thermal mass. I was planning on optimizing the differential by trying to reach a target compressor run time. I have a robust electricity monitor in my house so I know exactly when the compressor cycles so I can make changes and let it run for 12-24 hours and see what happens



K

[KillianBoy]

kupermanp,
Yeah you could put sensor on keg, in bottle of alcohol, bottle of glycol or whatever you want, adjust for thermal mass and test, adjust ETC and test, adjust ETC and test, adjust ETC and test, adjust ETC and test, adjust ETC and test, adjust ETC and test, etc then finally find the right setting after maybe several weeks, and many kegs. This is science but not rocket science, the best way to find the beer temperature is to test the beer (or water in a bucket).
Two ways to go either sensor air and do as THE ICEMAN says and 3/4 degrees differential or go with water and differential of about 1 you should be good, I'd do as THE ICEMAN says. If you want to sensor keg you will have to do it real life one keg at a time and go through as I presented above.
Honestly I would do air, 5 gallon bucket (3-4 gallons full), and test every 2-3 days, once you find the temperature and cycle you want, your good, no wasting beer and time.
KB