sorry if this is a question that’s been answered already. I’ve just completed a brew for a Belgian saison using wyeast 3724 and I’ve suffered the all to common stall that this yeast so often experiences. As the ambient temp in my home is circa 19c, I decided to try and kickstart the yeast back into action by raising the temp (this yeast is happier in the late 20s and up to 32 according to wyeast site).

So I invested in a mangrove jacks heat pad as well as their dual temp controller (which is simply and branded stc 1000).

My question is twofold (I’m not an electrician and don’t profess to know anything about how it works):

1 - as I’m looking to get the temp initially to about 25 or 26c and hold it there, I won’t need a cooling aspect (i.e. fridge) as the room will slowly bring the temp down and the hysteresis setting will see to it that it doesn’t drop far. But is it okay / safe to just leave the cooling socket empty? I.e. the controller won’t burn itself out trying to drive something that’s not there? (I accept this might be a really stupid question)

2 - with the ambient room temp at 19 and a target of 25 or 26c, the heat pad is probably going to be put through its paces and spend quite a decent amount of time switched on and heating (it’s currently been on for 6 hours straight which is what it’s taken to heat my brew from 21 to 24c). It’s a 25w pad. Anyone know if these are robust enough to just hook up to the stc 1000 and leave them to do their thing like that?

  • 2
    The STC is rated for much more than 25W. I use a 60W lightbulb and small fridge with mine.
    – uSlackr
    Commented May 1, 2019 at 21:32
  • 2
    Having gutted STCs in the past, the relays are generally rated to about 10A, so 2400W (at 240v). Totally fine for a 25W device
    – Frazbro
    Commented May 1, 2019 at 22:30

2 Answers 2


Don’t worry, stupid questions do not exist, especially if it concerns safety.

  1. The cooling socket can be left unplugged, it doesn’t matter. Even if the controller turns the power for cooling on without something plugged in, it won’t burn/short-circuit anything.
  2. The controller is (or at least should) easily be able to handle 25W, even for months straight.

If you didn’t do it already, you might want to wrap the bucket in some blankets to get to the desired temperature. I have a 25W heating belt myself and in my experience it is just not enough to get to the upper 20’s without insulation.

Enjoy the saison, a great style for the upcomming summer!

  • Thanks for the response, much appreciated and definitely gives a little peace of mind. I went ahead and started with just the pad overnight. When I checked this morning it had reached the 25c target and switched heating off and was around 24.8, so it looks like it has enough power to get it where I need it (I think the ambient temp has risen a little last couple of days too to help it along and the instructions for the mat say it should be capable of keeping a 25l brew between 10 and 15c above room temp).
    – user14585
    Commented May 1, 2019 at 14:44

The STC-1000 has two relays, each of which is rated for 10 amps (i.e. 2400W if your mains voltage is 240V). Your heat pad draws about 1% of that so you'll be fine. The STC-1000 is made for repeated on/off cycles so there's nothing to worry about.


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