Switch Relay/Circ Pump not listening to Stat

Heat_newb

Hello -

I have a Weil-McLain P-WTGO-6 (Series 3) Oil-fired Water Boiler running baseboard radiant. I have a Taco SR504 Switching Relay running 4 Zones.

My issue is that zones 3 and 4 don't seem to be listening to their stats. Despite their set points being satisfied, the zone stays lit (RED zone indicator light) on the Taco, and I can hear the Circ Pump and furnace continue to run. They will continue to run in this manner even if I turn the Stats OFF. The only way I have been able to get it to stop is to disconnect one of the Stat wires where it comes into the respective zone on the Taco.

Thoughts?

hvacfreak2

Does your unit have 2 or 3 terminals for each thermostat input ?

JohnNY

Remove the thermostat wires and jumper the T-T (or end switch) connections on each zone. If doing that energizes the pump terminals and closes the X-X contacts, then your problem is in your thermostat/wiring.

hvacfreak2

Either way the question is weather or not voltage is present on the input wires. If it is a 2 wire input remove one of the wires and measure it's voltage to 24 volt common ( power input toward the left of the relay board has a common ). If there is no voltage present on that wire than I would suspect the relay board. If there is voltage present than the problem is in the wiring or the thermostats. If this is a 3 wire input use the W wire for testing.

HVACNUT

Are the thermostat wires for 3 and 4 from one cable? For example, zone 3 has red and white and zone 4 has green and yellow and they're from one cable and then split somewhere to there respective stats?
With 2 zones constantly running but stop when you disconnect a wire from TT, it seems like a dead short on a 4 (or more) conductor cable. Hang any pictures lately? Or any work using nails or screws?

ratio

What stats are on the zones? Stats that use TRIACs to switch loads, as opposed to a relay, can fail conductive, analogous to the contacts of a relay sticking closed. They can also fail conducting in one direction only, i.e. appear in-circuit as a simple diode. They also are somewhat hard to diagnose, as they require a minimum load on the output side to operate—a modern high-impedance multimeter will show them as conducting regardless of the state of the device. A meter with a low impedance range, like the Fluke 116, will give you valid readings.