Relay Wiring R845A

reghi

The relay (Honeywell R849 1030) was not activating the circulator pump. So, before I was going to change the relay I jumped the T-T wires and the relay worked. I am assuming that the relay is functioning and that the problem is with the thermostat or the thermostats wires.

Also, the relays that were activated showed 0 volts across the T-T terminals and that one that is not activating is showing 24 volts across. Is that the way it should be?

bob_46

you are correct

Paul48

The one showing 24V across it, means the contacts of the t-stat are open. If it reads zero, your meter leads are basically on the same wire, and there is no difference in potential. Or, there is no voltage present. You verify by moving your black lead to ground, and checking each terminal.

reghi

Ok, so when the thermostat is calling for heat, it should read 0 volts and when its not it should read 24 volts?

reghi

So, now the next step would be to jump the thermostat wires at the thermostat to figure out if its the wires or the actual thermostat that is bad?

Paul48

Yes....With your meter leads on the T-T terminals. Understand that when the t-stat contacts close, with your leads like that, you are on the same wire. This is how mechanics find a broken wire...It's called a voltage drop test.