Amongst all the other projects both sons have got me "helping with", we have an immersion heater.
He has an iphone and can switch various things on and off remotely. Apparently the house controller has switched contacts labelled "Immersion Heater" so he wired these to the immersion heater.
It worked for about a day. He then read the instructions and saw the heater was rated at 13A and the switch contacts in the controller at 3A.
He has asked me what sort of relay he needs to install next to the HW tank.
I have suggested
Is this OK? Are there likely to be heat problems with the box he mounts it in? I have suggested stranded wire via a choc block if the existing cable is solid core, crimped terminals and a decent, earthed metal box.
I don't think it would be easy to cable a controller output to the main distribution board, but would a "proper" way to do it be to fit some sort of relay/actuator in that in the supply to the immersion?