My heating system doesn't seem to be using any direct power at all on thermostat link.
Check this from my furnace manual, It's on Serbian so I'll try to translate that.
KOTAO = Furnace
ELEKTRONIKA = Electronics, that one was easy, lol.
SOBNI TERMOSTAT = Room thermostat
When it's connected like on picture 55 (Slika 55) it's not using room thermostat, otherwise, it can be connected to room thermostat like on picture 56.
I'm guessing based on schematics on top picture, this needs to be connected to NO and COM ports, so I'm guessing relays ?
Relay needs to be connected to RPi and thermostat wires to it's relay.
So based on one of links @kflmiami420 sent and based on this schematics from my furnace manual, this is what I'm thinking. Correct me if I'm wrong, please.
I should purchase something like this:
- I should connect the 5V from GPIO PIN4 to VCC pin on module
- Connect IN1 (Relay 1) pin from Module to GPIO PIN 11 (BCM17)
- From IN1 Relay, connect NO and COM wires to thermostat wire terminal , one that has a label of TERMOSTAT on pictures 55 and 56?
If that is correct wiring that awesome! The rest of the programming should be easy on my part, as long as i get the wiring correct.
I wanted to disassemble current thermostat that i have and that is connected to furnace just so i can see the wiring , but the guy who installed it somehow glued it all together, i cannot take the cover off.
EDIT: Just to add something from the manual
"Thermostat link must not have direct power! Thermostat link is pure contact, without dynamics. Due to that nature, it should not be connected via additional power supply otherwise it may come to short circuit or it could fry other components."