Thermostats - ancient technology

[nadimaj]

Incredibly, thermostats that need have high voltages running through them are still a thing in the year 2023 (even for new builds).
Has anyone come across a thermostat that behaves a bit like an alarm sensor output? I.e. runs of 12v DC and sends a simple on/off voltage (nominally 1v) to a GPIO terminal block? The idea is that there will be a GPIO RELAY board somewhere plugged into such terminals that can then (through whatever logic I program) activate a relay into which a heating/cooling source is plugged in.
Tx

 

[CBW]

No, but Nest uses a 12v source from heatlink to thermostat, probably others and then there’s ebus controls, which are lower voltage still, but only compatible with the manufacturer. There‘s also opentherm.

 

[DetlefSchmitz]

Heatmiser used to do a system using 12V thermostats. Last time I looked they seemed to be phasing it out though.

 

[stem]

Incredibly, thermostats that need have high voltages running through them are still a thing in the year 2023

Not too surprising really. Generally; as heating systems require a 230V supply to power the boiler, and any remote devices controlled by a thermostat such as motorised valves or a pump also operate at 230V; adding 12v into the mix would require an additional power supply, separate sets of wiring for the 12v and 230V and would complicate installation / trouble shooting etc. and increase the costs associated with them.

If you don't want to use mains voltage, some room thermostats are battery powered and have voltage / potential free contacts so they can be used to switch whatever voltage is applied to them, be it: 230V, 24v or 12v.

A possible exception are some combi boilers that have their controls internally (with the exception of a room thermostat) they offer the option of 230V or 24v control. However, with the introduction of the current zone heating requirements of the building regulations, most installations with combi boilers now have external motorised zone valves linked to room thermostats anyway, so we're back to the thermostats having to provide 230V to operate them anyway.