Either tube heater/ceramic bulb type or immersion heaters work fine, as long as you
put the STC sensor in the same medium as the heater, i.e. sensor into wort with immersion heater or sensor taped to outside of FV if using air heater.
This prevents massive build-up of heat as the mass of liquid will take a much longer time to react to heat source (lag), e.g. with sensor in wort, tube/ceramic heater keeps heating surrounding air way past the 18-20C, but the wort is only slowly increasing/catching up due to mass of liquid, or sensor taped to side with immersion heater, wort heats up but outside temp takes longer to show change (immersion heaters generally have thermostats so extra bit of security). In both cases sensor should not be directly beside heat source.
piddledribble said:
first time I've seen those, I wonder how efficient they are for heating an area the size of a fridge....? but they look fine.
Oh yea, there very efficient, too efficient sometimes.
Learnt the above lesson not once, but twice on same brew (STC connected to fridge & 60W ceramic heater, temp sensor in FV). Air temp inside fridge +40C as door opened, ceramic heater was too close to side of fridge, melted plastic/insulation. Moved heater (after clean-up) to top of FV came back a couple of hours later, top/ceiling of fridge nearly bubbling. STC still showing set temp, wtf? Realised that everything was working fine, just that the sensor was measuring the wort temp not the air temp, therefore heater kept working until wort caught up.
40w tube heater going to be used next, with fan & sensor taped to side of FV.