no voltage to thermostat on hot water boiler system

elvisnixon

One of the zones on my boiler stopped working, the other 2 work fine. There is no 24 volts to the thermostat on the bad zone. The zone valve manually opens ok. Do I need to replace the zone valve motor? Does the zone valve motor send the 24volts to the thermostat or should I be looking at something else? The other 2 thermostats and zone valves are working ok.

EBEBRATT-Ed

The thermostat is only a switch. You said
"no 24 volts at thermostat"

You need to check for 24 volts at the zone valve with the thermostat calling for heat

24 volt power has two wires. One leg of this 24 volts power will go to one of the zone actuator valve wires. the other 24 volt leg goes to the thermostat (usually terminal R). Terminal W on the thermostat returns to the zone valve to open it

start at the 24 volt source of power. Trace all wires and check the connections.

Intplm.

If you like, you can jump the t-stat wires at the t-stat (twist the thermostats wires together) on that zone. If the zone turns on the problem is a loose connection or a bad t-stat. ?
If it does not turn on, the problem is probably at the zone valves power head.

JUGHNE

You could have more than one transformer suppling power.
That zone valve may have it's own 24V transformer somewhere near the boiler.

STEVEusaPA

Intplm. said:

If you like, you can jump the t-stat wires at the t-stat (twist the thermostats wires together) on that zone. If the zone turns on the problem is a loose connection or a bad t-stat. ?
If it does not turn on, the problem is probably at the zone valves power head.

Explain to me how jumping the Tstat at the base will tell you that you have loose connections elsewhere or bad wiring between the tstat and the zone valve?
It will only tell you that it 'might be' the thermostat. It still may not make the circuit.

Intplm.

No. At the thermostat. Just trying to keep it simple for the OP. Bypassing the t-stat.