1 of 2 pumps turning off.

SeanBeans

my site manager is having a problem with his navien boiler system.

he has 2 zones.. both controlled by pumps.heres the scenario.

1. the upstairs zone is calling for heat and working fine.
2. when the downstairs zone thermostat is set for heating it turns on.
3. but when the downstairs turns on it kills power to the top floor.

I don't have pictures at the moment.
It is hot water baseboard.
controlled by taco control board

what other information would you need to diagnose the problem?

Dave H_2

Sounds like the priority setting is turned on for the downstairs zone.
the priority setting is typically reserved for DHW loads like an indirect tank. It will turn off all other zones until the demand for heat is satisfied and then turn on the other zones.

On the Taco SR panels or ZVC panels, the last zone on the controller is this priority zone. Just to the right of that terminal inside the controller is an on/off switch.
Switch it to off when you do not want priority.

Dave H.