Wiring smart thermos

kpmply

I added some smart thermos and tried wiring them.  Problem is when I call for heat on 1 zone, 3 zones come on in my Argo ar866 6 zone relay. Not sure why. Wondering if it has to do with isolated switch. I am piggy backing on transformer that powers that switch. 

Jamie Hall

Back to basics. A thermostat -- however smart it may be -- is a switch so far as the heating system is concerned. However, the smart ones are also little computers, and so they need power.

OK. Almost without exception, the power will come from a transformer somewhere, which will be connected between a terminal labelled R, Rc, or Rh, and a common. That keeps the lights on in the thermostat and its little computer ticking away. Now for the heat, there will be a third connection -- commonly W, but it may be something else. When the thermostat is calling for heat, that connection will be switched internally in the thermostat to connect to R or Rh.

Now to make a relay work, it has to have power to its coil terminals. That doesn't have to be the same power as the thermostat, but it may be. For power to reach the coil terminals, it must start from the power source, travel to the thermostat R or Rh, travel through the internal switch in the thermostat, travel from the W terminal on the thermostat to one terminal on the relay coil, through the relay coil, and then back to the power source's other terminal.

In your case, it is likely that somewhere the wiring is not done correctly, so that when any thermostat calls for heat, power is sent through that W terminal to all the relays, rather than just the one wanted.

You need a complete wiring diagram to figure out what went wrong. If you post one, maybe we can help find the problem.

kpmply

Pretty sure I wired it wrong. Will draw up diagram and post it soon. Thanks.