Recipe calls for fermentation at 70°F (21°C), basement is 65°F (18°C). I know that fermentation produces some heat, so I was wondering if just letting yeast do its thing will be enough.
Otherwise, do I need to move my carboy to a warmer room upstairs or find a way to heat it?
The temperature rise will be depend on how vigorous the fermentation is, and on the volume and shape of the vessel you ferment in. You'll see a temperature rise of about 5-10 degrees on the homebrew scale, in my experience. Still, it varies widely.
I would suggest getting one of the thermometer strips available at your local homebrew shops. They are reasonably accurate, and they're an easy way to monitor the actual fermentation temperature. And they're cheap.
If you find that your temperature is too far off, there are some cheap and effective ways of controlling temperature, up and down. For example, if you find that your temperature is too cold, you can use an aquarium heater to warm it a bit. If you find that your fermentation is too warm, you can use the "swamp cooler" method by wrapping the fermentor in a wet towel or cloth and putting a fan on it, or put it in an ice bath in your bathtub.
All of that said, if there aren't drastic swings in temperature (such as might result from strong drafts or being near a heating vent), then your 65°F (18.3°C) basement will likely give you a good, not-too-hot fermentation. Still, I would get a thermometer so that you can monitor it.
Yeah, pretty much any ale yeast will do fine at 65.
I had a Russian Imperial Stout that I was keeping at 65 in my temp controlled chest freezer. I took it out during fermentation to clean up a messy blow-off, and it was up to 72 within minutes. So fermentation can generate quite a bit of heat.
I would be curious if this person was using a stick-on thermometer, wise choice, but that would explain the wild temp changes. it reads the temp it contacts and if the ambient temp in the "freezer" was 65 and outside was 72, well there ya go. secondary convincing: how long does it take to heat up 5 gallons on a burner or stove? it would take a crazy amount of fermentation heat to go up in temp that fast
Yeah, pretty much any ale yeast will do fine at 65°F (18.3°C).
I had a Russian Imperial Stout that I was keeping at 65°F (18.3°C) in my temp controlled chest freezer. I took it out during fermentation to clean up a messy blow-off, and it was up to 72°F (22°C) within minutes. So fermentation can generate quite a bit of heat.
@Pasha I have tried to estimate this here. Look up your original specific gravity on the plot and read across to get a (rough) estimate of the expected temperature rise. For example, for a specific gravity of 1.045 we would estimate a rise in temperature (above ambient) of ~5F / ~3C. In this case, you would want to cool your wort to a temperature this many degrees below your target temperature.
