unfamilar was asking about these on Sunday so I thought I'd post it
have used these twice and they seem to work great
Very easy to set
https://www.ebay.com.au/itm/20A-12V-Re ... id=p2047675.c100005.m1851

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Where do you stick the temperature probe? (no funny answers!)

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The sensor goes in the lower radiator hose

So could cut the sensor off the ebay controller and use one of those thermo switches. Rating for the temperature switch might be about 80degC? since it's on the outside of the hose it might not match the water temp exactly.

Well the eBay controller is adjustable, is it not? I would use the sensor that comes with it. Never seen that kind before so don't know exactly how it mounts up but it's got to measure the radiator temp somehow

Ah right I get it. That picture is of a little $2 thermal switch, they have a cut in and cut out, usually something like 80C on - 70C off, depending on model. It's something you might use instead of the controller.

The ebay controller has a probe that could also be cable tied to the lower radiator hose or jammed in the radiator somewhere near there. Might read a little inaccurate though.

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