Fridge/Freezer misuse to brew beer?

[ericmark]

I have a Hotpoint Fridge/Freezer which was condemned as the insulation had failed. There was also a problem when one opened the door the light started to flash but it still did work, clearly a problem but what I wanted was to move beer brewing into the garage which in the main does not need the fridge all it needs is a heater and thermostat which I have set up using a demo under floor heating tile 18W and an electronic temperature controller.



However summer months are the dry season and from earth June to mid September brewing stops. I have been considering next year trying to brew through the summer and so have been monitoring the first brew of the season.



It would seem 60W refrigeration is too much, to cool down 40 pints takes time and if I simply connect both fridge and heater then the fridge will cool down to 5°C or what ever fridge is set at well before the brew cools down to 19.5°C I am aiming for. To sense air temperature will not work as air temperature and brew temperature start the same but then the brew produces heat so will become 3 to 4°C hotter than the air. But as time goes on it will return to same temperature.



It would seem three methods to get around the problem. 1) Change the settings on the controller as the brew progresses, not really a good idea as not really sure what stage it is at. 2) Limit how cool the fridge air will go, at moment around 5°C raising this to say 17°C would reduce over shoot. 3) Limit time the fridge runs for.



Likely the latter is the easiest just fit a time clock with 1 out and 9 in as it goes around the 24 hours so maximum run time is 15 minutes. However need to buy new controller anyway as one I have will either heat or cool but not both together, so using old one to limit how cold will likely be cheapest option.



However what ever of the two methods I use the fridge/freezer will be switched off and on with a regular self test and I wonder how long it would run anyway if being switched on and off all the time. Plus no idea what temperature freezer will reach.

At the moment in an emergency I can take out the fermentor and press it back into service, don’t really want to loose this option so not really willing to destroy it just for an experiment.



So will switching on and off all the time destroy my Hoover HCA 394 FK PW fridge/freezer or is it likely it will not damage any more than normal use? And of course if there is a way to alter the temperature without using external temperature controllers then great.

 

[fender]

Have you worked out how many times it will stop / start per hour?

 

[ericmark]

Well with timer once and hour however rather a surprise today I have been monitoring brew temperature and fridge air temperature. I had dismissed brewing with fridge door open as thought brew would get too cool at times. However now past high activity stage and garage at 16.2°C and inside fridge air at 17.5°C and brew at 19.5°C so it seems ambulant temperature around the fermentor can be quite low and heating tile will still maintain brew to correct temperature. So the answer is simple, in summer simply open fridge door.

Maybe I will have to delay a brew start in summer, it needs to be cooler for first few days, but here in North Wales about the most North/East point seems I don't need to cool brew after all.

Of course those in the South will still have the problem and what my readings have shown it's no good controlling fridge air temperature and hoping brew temperature will be the same. But 40 pints takes a lot of heating or cooling, nothing happens quickly, so I would say a timer with one out and three segments in, (with run 15 minutes in every hour) on the fridge supply would likely reduce fridge running time to a reasonable figure and the over shoot would not be enough to worry about.

 

[fender]

Running the fridge with the door open will just make it run continuously as it will never really reach set point.
If under other circumstances you are looking at a run time stated as 15 mins in every hour - that's fine.
The main thing that will cause a compressor failure is very frequent stop / starts. As long as you have 10-15 minutes between starts, you should be fine.

 

[ericmark]

Sorry poor English on my part. Door opened instead of running fridge. I want brew at 19.5°C most of year the unplugged freezer used simply as an insulated box works fine. I use a small 18W panel on floor of fridge which the fermentor sits on so heat direct into fermentor when required, the panel is powered from a temperature controller which has a sensor held against the fermentor side with a sponge insulating it from surrounding air.

The odd hot day is not a problem 40 pints does not heat or cool quickly. However with door shut the heat produced by the fermenting can rise the temperature over the limit. So using a fridge would allow brewing in July and August. This is why we have the beer festival, it celebrates first brew of the year after summer recess.

My stock this year is getting low down to last 80 pints, and I like to leave in bottle for a few months before drinking. So thought worth looking at all year round brewing again.

I was worried about brewing with door open as a cold spell could cool beer too much. However using temperature probes I now realise the fridge runs a couple of degrees below fermentor even after the peak has gone so with temperature controller switched on even with door open the ambient temperature need to drop below 14°C before there is the slightest chance of the heater not keeping up.

Clearly commercial brewing involves higher quantities so they can't get away without refrigeration, but I would guess the heat is removed with liquid not air, heat exchange liquid to liquid is more rapid than liquid to air and I am sure they have far better control than I can hope.

Anyway thanks for help I have around 10 months before I need to do anything. Likely I will just build up a stock again.

 

[SFK]

Eric,
Why not cut two holes in side of freezer and put in one or two fans connected to thromostat. If brew temp goes above say 18oC then fans come on and remove hot air from Freezer. I would use use bathroom fans with shutters so freezer is a sealed box when in winter and heater is on.
SFK

 

[ericmark]

I did consider using green house vent controls to open the fridge door. However as I have said it seems the fridge air temperature is at least 2 degrees lower than fermentor so it would seem if the garage is over 15°C I can simply open the door of the fridge and tile will have no problem maintaining the fermentor temperature to 19.5°C. So come next June I simply open fridge door and leave it open until mid September.

When I started this thread I had not got any readings from the indoor / outdoor thermometer only the controller the latter only reads the fermentor temperature. The results were rather a surprise to me. I had expected the fermentor temperature to be over the air temperature in early stages, but thought as the fermentation reached the end the two temperatures would draw together. However one week into fermenting means nearly over and still readings are fermentor 19.5°C Fridge 17.7°C and Garage 16.2°C with the tile hardly switching on so completely modified my ideas.

In hind sight and hind sight is easy my test should have been a fermentor full of water and leave on for a few days without the controller to see how many degrees it would heat it above ambient. Again hind sight is easy, I should have realized when brewing in kitchen and temperature had dropped I used tile and forgot about it and 12 hours latter ambient around 18°C fermentor was showing 26°C did not kill yeast, but the beer was rather bitter drinkable but not a good pint.

Since then I have realized the fermentor was likely hotter as the stick on thermometer is cooled by the air as well as heated by the brew. A sensor pressed against the fermentor under a sponge would have shown a couple of degrees more.

It is a learning curve. Many seem to measure air temperature and they quote temperatures for brewing cooler than I use. I thought at first it was just a different yeast, now I realize it was where they measured to temperature.