Hi there guys! I am hoping someone can help me. I have just purchased a new SMART thermostat - please see circuit diagram. I am replacing a SIEMANS RAA20 traditional rotary thermostat - about 15 years old - I also include a photo of the wiring inside the old thermostat. Any help would be very gratefully appreciated! Thank you in advance.
Installing a SMART Thermostat
- Thread starter MrKipling
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1st thing to establish - do you know that the unused grey core of that cable is a neutral? I know it has a blue sleeve, which is hopeful, but your existing stat does not need or use neutral, and your new one does, and without one it won't work.
Basically the new one needs a permanent mains supply but the old one doesn't, and in fact doesn't necessarily have to be switching 230V.
Like the new one, the switching contacts are volt-free, i.e. they could be switching anything (within the limits of their rating), so they can be used with a boiler which just needs a contact made between two terminals, or one which needs mains voltage applied. The photo of the example wiring shows a connection at the stat between L and one of the switch terminals, so that is from an application where the boiler does need 230V applied to it.
On the basis that you should have a multimeter just as much as you should have screwdrivers, carefully test to see if you have 230V between brown & grey.
Basically the new one needs a permanent mains supply but the old one doesn't, and in fact doesn't necessarily have to be switching 230V.
Like the new one, the switching contacts are volt-free, i.e. they could be switching anything (within the limits of their rating), so they can be used with a boiler which just needs a contact made between two terminals, or one which needs mains voltage applied. The photo of the example wiring shows a connection at the stat between L and one of the switch terminals, so that is from an application where the boiler does need 230V applied to it.
On the basis that you should have a multimeter just as much as you should have screwdrivers, carefully test to see if you have 230V between brown & grey.