I'm conscious this is the third question I've asked before I even get started on my first brew, but hey-ho; better to learn from the experience of others and get as close to "right" first time.
I am about to start an ale brew and understand the ideal temperature for fermentation to be effective is in the range of 18 degrees centigrade (c. 64F) to 22 degrees centigrade (c. 72F) - maybe even 20-22C.
My problem is that where I live currently (north west England) the outside air temperature is a crisp 4-8C during the day dropping to freezing at night. The impact of this is that even with regular central heating, the best indoor range of air temperature I can get is between 15C (lowest) and 18.5C (highest) - having taken regular test readings at intermittent intervals throughout a few days - and I am not sure how these factors would impact on the temperature of my brew and fermentation. I don't have a home thermostat in order to keep a constant, so the indoor temperature fluctuates with the timed on/off intervals of my central heating (presently 1.5 hours at 6am, 1 hour at midday and 2 hours from 5-7pm).
I had considered a number of options to maintain a decent temperature including heat mats and brew belts and I am comfortable with the pros and cons of each and their potential effects on the brew. I have ruled out more expensive thermostatic options as too expensive to blow on my first brew.
Does anyone have any thoughts on how they would maintain a suitable temp during fermentation with these conditions? Has or does anyone currently brew ales in these conditions with positive results?
Interestingly, I have read that active fermentation can warm a brew by 5-8C, so assuming I get the fermentation going in the correct range, is it possible that the heat given off during fermentation could actually keep my brew in the correct range anyway?