I have an STC-1000 temperature controller which I use to drive my fermentation heating/cooling system, it's wired as follows (except on my STC the hot and cold are the other way round:
It looks like this (shown here during testing):
H is obviously hot, and cold is the one with a plug in it. Those are UK standard mains plug sockets with Live, Neutral and Earth pins. Mains electricity in the UK is 240v. The controller works fine; I've probably run it for 12+ weeks now in total with no problems.
That's the background, here's my problem/question:
I use the temperature probe to tell me my mash temperatures already (easier than using a glass thermometer). I'm thinking of making an electric kettle for BIAB. I would like to use the STC-1000 to switch the kettle element, however the relay in the STC is only rated to 5 or 10A (I forget which - adequate for my fermentation control system but not for an element). Therefore, I would need to use some sort of relay.
I have two options currently, unless there's some I haven't thought of -
1) build a standalone relay which plugs into the hot side when I want to use it and has it's own mains supply. The STC would switch the relay which would handle the higher demand of the element.
2) wire a relay into the current setup between the STC and the plug, same idea but neater execution. I would have to change out the power cable too as I only used 5A cable (better safe than sorry/it was cheaper).
What sort of relay should I be looking at? Does this sound like a reasonable solution?
I probably haven't explained myself very well, so if you need some more information just ask...