Thermostat replacement with relay module


I have Salus 091FLV2 thermostat to control temperature at home. It is pretty dump device. I’m thinking to replace with something smarter. The question is would it be to possible to use relay module instead?

Thermostat is connected to boiler with 2 wires. Per description the thermostat can handle up to 5 A which should be ok for relay module. However I kinda don’t understand the electronic part so I hope it will not catch fire :smile_cat:


Hi, based on Salus datasheet the relay has parameter “5 (3) A”. That should mean that it can handle 5 A short-time current. And 3 A constant-current.

Here is our relay

It also has 5 A short-time current. So it might be compatible.

If you have some modern heating device, usually it has low-power logic input which does not switch any heavy currents like pumps and valves. This switching is usually done by relays in the heating controller. So it might be ok. However if you have multimeter, you can check that by shorting those 2 wires to thermostat with a multimeter set to amps. The you will see how big current really flows.

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