I intend to get a frost stat heater. I've looked around the local shops and located one that will come on when the temp drops below 5. I would rather wait until it drops to 2 because doing it below 5 would use more electricity. It's for a concrete block room that is about 4m x 3m (standard ceiling height). I'm going to be setting up a more appropriate RO in there soon (ditching the merlin due to now being on a water meter) but I don't want to do so until I've ensured that things won't freeze. I'm still awaiting a few fittings too as I messed up and ordered a couple of wrong bits.
Any recommendations? Preferably one that I can collect as deliveries can be tricky here.