Troubleshooting Grundfos UPZCP relay issues

shawncal

Hi all,

We installed a new distribution and controls on an older Weil Mclain CGA boiler last winter. There is a main circulator at boiler return And 4 zone pumps controlled by a grundfos UPZCP-4 relay. 3 of the 4 zones were used and the system was up and running well for last winter, then shut down for the summer. We disconnected water plumbing for 2 of the zones (as we removed radiators to renovate those spaces) and the other was left untouched. Upon restarting the system today, the controller is not working properly. When activating thermostat for any of the zones, the boiler fires and main circulator energizes, but the circulator for that zone does not (nor does the light come on at controller). When activating a thermostat while boiler is already running, the system shuts down entirely!

The Grundfos controller is energized and 3 red LEDs illuminating the logo are always on, but not getting power to any of the zone pumps regardless of tstat setting.

To my knowledge, nothing was changed with wiring/controls since last winter, and so confused as to why it seems haywire.

Any thoughts appreciated.

hot_rod

Any thermostats changed during the down time?
You could disconnect all t-stats in the relay box, see if the lights go out. If so, the wiring or t-stats could be causing the problem.

shawncal

No change to thermostats and all three cause same symptoms with boiler (turn on boiler and primary pump only, but not the corresponding zone pump)...

hot_rod

It could be a bad circuit board, they don't often fail during off season. A lightning strike maybe?

Two way to troubleshoot, with a volt meter, or remove wires and eliminate potential causes.

Some brands use a double pole relay for each output, so as it enables a heat call for the boiler it should also send power to that circulator.
Does it have yellow disc thermal circuit breakers? They will trip if there is a short, and reset after a minute or so.

There may be dip switches or pins with jumpers that change the logic of how the outputs power, nothing changed there?

As I mentioned above, if you remove the thermostat wires, you eliminate that potential cause.

Be good to know before you install a replacement.