Hot water heat, one boiler, two zones?

[KMS - Brett Anderson]

I have a Weil McLein 230 boiler. It has one input for thermostat and one output for circulator.

It's going into an existing structure with two zones, two pumps, two thermostats. No zone valves, pumps are on boiler input, so one running doesn't cause other zone to circulate.

My question is, how do I wire both thermostats into the boiler, without feedback triggering the second pump? Both pumps run via relay.

I've tried diodes, but can't seem to get anything to work right. Was wondering if someone could point me to a wiring diagram of the electrical layout in the above application.

Thanks

Brett Anderson

[Mark Monson]

The relays must be double pole type. One set of N.O. contacts are used to start each zone pump switched by thermostat. The other set of N.O. contacts are used to run the burner. Either zone calls for heat, its pump runs and the burner runs.

If you aren't qualified to work on this stuff, call somebody who is.

MM