Our system is setup with a Buderus GB142 boiler, that provides both HW and supplies 2 radiant heat zones.
We had a lengthy outage on the GB142 while we replaced the transformer and UBA
Now the HW works, but having an issue with the radiant heat. The ZVC-403 valve controller is wired to two thermostats, each controlling a separate zone, and each zone having multiple Caleffi zone valves.
When the thermostat calls for heat, the TStat light on the ZVC lights up. Good sign.
Once the valve warms up, the valve light comes on. Good sign. And the valves are warm to the touch, so its more than just the light.
The ZVC should then send a signal to the boiler (and the pumps?) via the end switch terminals. The signal to the GB142 goes into the AM10 module, then out to the boiler.
Here's where I seem to have the issue. The AM10 doesn't register that there has been a call for heat. So I tried to bypass it and connect the wire coming out of the ZVC end switch directly into the TT Connection "WA" on the boiler. Still no firing.
I should note as well that when I did this, I turned the power off to both the boiler and the ZVC (wall switch upstream of both). When I turn it all back on, the pumps run for a few minutes, and then turn off. I'm assuming that's just a priming mode or something.
So all of this leads me to believe that the ZVC is not sending a signal to the boiler.
Last piece of info, the screws on the end switch terminal have quite a bit of corrosion (see attached image). Other screws have similar corrosion (like on the TStat and valve connections). Seems like water may have gotten in there at some point).
While I try and hunt down my multimeter (how does THAT go missing?), any ideas?