Beer kit brewing and temperature control.

[ericmark]

I started brewing home brew around 4 years ago, and the summer brew was not good, but the winter brews were, although they could take over 4 times as long as the instructions stated. Step one was stick on temperature strips, and using old body warmers to keep the brew a little warmer in winter months.

Then the fridge/freezer although still working, was condemned as uneconomical to repair with an insulation fault which caused a ice build up in back of fridge. So this was moved to garage and I got a temperature controller and an old demo under floor heating tile and moved brewing to garage in a temperature controlled fridge.

The results were no daily monitoring just start it off then three weeks later bottle. During the Winter no cooling required worked well, the fridge/freezer still worked so no reason could not also use cooling only in the summer which I have started this week.

However during the time of year when heating and cooling may be required then there is a problem. The controllers have a differential so set at 0.3°C you will get for example.
19.5°C heating starts.
19.8°C heating stops.
20.1°C cooling starts.
20.4°C cooling stops.
The problem is the gap between heating and cooling needs to be larger than the gap between heating starting and stopping and cooling starting and stopping. The problem is the size of fridge/freezer motor it is too big, so monitoring the fermentor when the motor starts it brings the air in the freezer to around 2 ~ 4 degrees colder than the fermentor with a 0.1°C differential with 0.3°C even worse. So after the motor has stopped the fermentor is still cooling. I have set delay to maximum of 15 minutes but again delay works on both heating and cooling.

At the moment the cure is to use two temperature controllers. The one with 0.1°C differential is used for cooling and one with 0.3°C differential for heating, also I use a very small heater just 8W so unlikely that on heat it will over shoot.

Others I know use air temperature instead of fermentor temperature and use a fan to help transfer heat, they also have to compensate using a lower temperature to start with and increase the temperature as time goes on.

However if too low the fermentation will not start so with the 9 x 0.3 = 0.9°C of the controller added to the 3 ~ 6°C between fermentor and air temperature with minimum starting temperature of 19°C it means 23 ~ 26°C peak which is too high or a nearly hourly check of temperature as the fermentation starts and as it does reduce the set temperature which likely means the refrigeration motor will start.

Once running I found in the summer my fermentor stayed at 20.1°C at start of 18°C it started the refrigeration motor which caused a dip to 19.9°C at fermentor on first starting but after that first dip it remained at 20.1°C every time I looked. So turning off heat during first 24 hours may be enough to stabilise the running and stop any yoyo between heating and cooling.

But the STC1000 is 0.3°C only the MH1210A is 0.1°C differential and that one is heat or cool only the STC1000 does heat and cool. So I use two controllers for single brew until winter months, when if running low I can go to one brew in fridge and one in freezer.

I do wonder how those with a single STC1000 run in the summer?

 

[cjard]

Would adding some literal mass (thermal inertia) to your fermentation vessel help smooth out the swings?

 

[ericmark]

Well it is summer, well should be temperature outside at the moment 10.8ºC not much better in garage at 14.5ºC, but early June did have a warm spell and I have tried two brews using refrigeration and the results were not as expected.

1) It seems my fridge/freezer cools the freezer first so only the freezer gets any refrigeration not really a big problem, but the freezer is too low to syphon so have to transfer to fridge to finish off.

2) The air in the freezer went down to 5.6ºC, the fermentor went in at just over 20ºC with the temperature set at 18.5ºC with a 0.3ºC differential in spite of air hitting 5.6ºC the fermentor did not over shoot by even 0.1ºC with the sensor on the fermentor. That was not what I expected, but when the freezer is running there is also a circulation fan running it is part of the frost free system. And the evaporator is behind a plastic panel so when freezer switches off there is a rapid increase in freezer air temperature. With the start delay and the freezer self check after first switch off it hit 19.1ºC before motor restarted.

Using a chest freezer or a fridge may give different results. But in my frost free freezer there is really no option one has to monitor fermentor temperature or the motor run time would be far too short. To get the fermentor down from a little above 20ºC to 18.5ºC first run time was 40 minutes. I say a little above as the temperature was settling as the new mix was put into the freezer, so don't know exact temperature.

Today I have reconnected the heaters, I did not expect to need them, but brews down to 17.2ºC using a 8W bulb in freezer and 18W tile in fridge, the tile is really too big watts wise and holds too much heat, so I will unplug for a time and allow heat to go in slowly so as not to over shoot. Good job I wrote this forgot to change fridge controller to heat instead of cool.

After 1¼ hours the freezer air was at 21.6ºC but fermentor still at 17.3ºC not really moved. As to fridge that will now start to rise what I have done in the past is set controller to less than required and slowly moved it up. But since brewing at 18.5ºC and it can hit 22ºC without messing up the brew at this stage I am leaving set to 18.5ºC.

 

[ericmark]

Went to do a Coopers kit and found the recommended temperature much higher, they say 21 - 27°C where most kits say 18 - 24°C so lifted up the temperature a little to do Coopers kits. The Youngs kits are clearly better with temperature control, they have lost a lot of the bitter after taste, however using brew enhancer also removed the bitter after taste. Most British kits say use sugar, but the Australian kits (Coopers) all say use either brew enhancer or dried sprayed malt which reduces the bitter after taste anyway so they could be brewed even with a British yeast at the higher temperature and get away with it.

Also the Coopers kits do not give all info on the instructions on the can, you have to go to web site to find out what the "recommended fermentables" are, they do a list:-
Australian Pale Ale 1 kg Brew Enhancer 2 Start 1.038 First 1.008
Canadian Blonde 1 kg Brew Enhancer 2 Start 1.038 First 1.008
English Bitter 500 g Light Dry Malt Start 1.031 First 1.006
European Lager 1 kg Brew Enhancer 3 Start 1.038 First 1.010
Irish Stout Brew 1 kg Brew Enhancer 3 Start 1.038 First 1.010
Mexican Cerveza 1 kg Brew Enhancer 2 Start 1.038 First 1.008

However the English Bitter kit I bought is listed, but the Stout is not, the picture for Irish Stout is different to that for plain Stout so one assumes they are different kits? I have written a note to self, tell people not to do a Coopers kit as a first kit. On one forum they do reviews of kits, for the English Bitter every report stated they had used 1 kg of fermentables, nearly every one can kit does used 1 kg, the English Bitter is an old one out with only 500 g, but it is so hard to get the instructions having to find it on Coopers web site, it seems people just guess it will be same as other kits.

 

[ericmark]

Well there has been a lot of talk this summer on how to keep a brew cool, most people use a fridge, I use a fridge/freezer as it is what I had. But some people have not got the room for a fridge and so been looking at other methods. The simple method is the builders trug filled with water and a towel wrapped around the fermentor with part of it in the water so that the latent heat of evaporation cools the brew. Not sure if this actually takes up any less room than a fridge, and it does mean humidity in the room drops.

Be it the builders trug, putting cool packs either on the fermentor, or in the brew, putting a insulated bag around the fermentor with a ice pack, these all lacked one important feature control.

Knowing my fridge/freezer is some 20 years old I have been looking at what to replace it with. I have been looking at the Thermoelectric Peltier Semiconductor Refrigeration Water Cooling System,

I don't like the peltier system as it is very wasteful, but it is only for when the weather turns unexpectedly hot. I could dispense with the peltier and simply use a container of cold water, it is not the cooling of the water I was looking at but the ability to turn a water pump on and off. Using a water pump means I can use a temperature controller to turn on the pump when hot and turn off the pump when cold. Now I am looking again at the latent heat of evaporation, if the water is returned to run down a bit of towelling specially with a small fan aimed at the towelling then the return water can be cooled to less than ambient as long as humidity is not too high.

Problem is I am lazy and likely will not bother building a unit until my fridge/freezer fails. But thoughts please, would it likely work?