What dictates brewing temperature?

[Srengam]

Is it the kit or yeast?

For instance, I'm brewing Muntons premium which suggests brewing temp 18-20. But I'm using Safale yeast which says 15-27. At the moment temp isn't a problem, but as the cold comes in, will the combination of Muntons kit and Safale yeast be OK if the nightime temps drop below 18.

I'd be surprised if it does drop below 18 to be honest, but just incase, I wouldn't like to ruin a brew because it got a little cold.

Cheers all.

[Yeasty Rob]

Someone more knowledgable might correct me, but I'm almost certain its the yeast.

At different temperatures the yeast can product different levels of certain chemicals. Some are desirable, and some not. You need to get the temperature right for the style of beer you want.

For instance if you brew a lager (even with lager yeast) at a higher temperature, you will end up with more of an ale taste.

[Rookie]

It's the yeast.
If your fermentation place is going to be near the low end of the yeast's temperature range you can throw in an extra pack of yeast or make a starter if using liquid yeast.

[richc]

Making your fermenter warmer is usually pretty easy (compared with cooling it). You can get a temperature controller and a warming belt pretty cheaply (~£30) which will allow you to pick the fermentation temperature you want.

[cellone]

It's down to the way of the yeast.

[Srengam]

Thanks all.

I've actually got 2 water baths in the garage which were both fine throughout last winter, I've been watching the temp in the house and it never falls below 20 degrees, so to save a bit of money on running a pair of 300w heaters, I've moved an FV indoors and it's been fine. I'll continue to use S-O4 too.

So in theory, as long as the house stays above 15 (the low range of S-04) then I should be fine.

Thanks again.