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I am having some issues keeping the temperature controlled. I live in SE QLD and the daily ambient temperature has been 23 degrees C down to 11C. I've been advised not to let the wort drop below 18C but it has been lower, about 15C with a high of about 22C. I would like to know
1 What are the ill affects of this (other than the yeast becoming inactive)
2 If I leave it a bit longer and get the temperature regulated (towels and a heat pad) Would I be ok to leave it for a couple of weeks and then check the hydrometer before bottling?
Thanks

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What yeast are you using? –  Sneftel Jul 8 at 16:37
    
I have just used the yeast packs included in the cans of Morgans brew kits. –  Snarf Jul 9 at 9:39
    
Reading the stockist website I am fairly sure that I am using Saccharomyces Cerevisiae morgansbrewing.com.au/products/hops-yeast. It seems to be the standard one that they supply. –  Snarf Jul 9 at 20:56
    
@Snarf, WOW, I do not trust that site's yeast description at all. They say its a "Lager Yeast", but identify it as Sach. Cerevisiae (lager yeasts is actually Sach. Pastorianus), and they say to ferment it ideally at 22C/71F and up to 32C/89F, which is FAR outside the temp range for all lager yeast anyway. For your next batch, order some dry yeast from Fermentis instead. –  Graham Aug 12 at 13:38

3 Answers 3

Idiot-proofing the fermentation temperatures has been a bit of a peeve of mine right now, as I use a family member's basement as a brewery and I have little control of the ambient room temperature.

The DIY solution I am working on uses a $15 digital thermostat/controller with a sinkable probe from Ebay to switch on/off a typical brewing heat belt (a FermWrap would be better if I had one) at set temperature thresholds.

Follow this video tutorial on YouTube, plug in and install the heat belt and sterilize/sink the probe into the beer.

I have seen people use this system to activate a space heater for entire brew rooms, which might be economical if I wasn't using an entire basement.

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Yes, you will need to extend the fermentation time, as cold will slow down the yeast's ability to reproduce and ferment. Your best bet is to get a temperature controller (e.g. STC-1000 or Johnson digital controller) and accompany that with your heat pad or a purpose built FermWrap from MoreBeer.

Worst case, you don't attenuate all the way, and then when you bottle, you risk the yeast kicking back into action and over-carbonating your bottles with dangerous consequences. Less pessimistic would be to have them drop off too early and you'd have a sweeter than normal beer. Other side effects include flavor production depending on the yeast used. Some yeast produce certain flavor compounds at certain temperatures. Take a typical Hefeweizen yeast such as WLP300. They tend to produce more clove flavor at below-optimal temperatures, and banana at above-optimal temperatures. To balance them, you would need to ensure proper fermentation temperature.

Also, if you can steady the temperature with heating & cooling, your temperatures sound like they'd do well for lagers.

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Thanks for the advice –  Snarf Jul 9 at 11:35

It's not as bad as you think. Remember, you have 20 l of beer. It takes time to warm it up and time to cool, so temperature fluctuations in the fermenter will be smoothed. I would wrap the fermenter in a blanket and leave like that for the normal fermentation time.

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