Vitodens 100 WB1B - Hot water but no heat

[sawback]

I have a 10-yr old Vitodens 100 WB1B. This fall a leak developed: the air separator located in the boiler above was leaking, and water dripped down and infiltrated the pump electrical housing in the Combi unit. This shorted out the Combi pump which then blew a fuse. I corrected the leak and dried out the pump and things worked again for the last few months. The other day the pump stopped working again and the fuse blew. I dismantled the pump and found that one of the pins that attaches the fine copper magnet wires had corroded and that's what was causing the fuse to blow. I hardwired the fine wire to the pump electrical housing pin (the one with the capacitor, etc.) and it seemed like problem solved. The motor spins, the fuse doesn't blow. I re-installed the pump, purged the system, tested hot water (works) put it into Service > Relay Test to check the heat to the radiator system was working (it did). But upon resetting the system the boiler comes on, cycles through the startup sequence, and then stops. Call to heat does nothing (no radiator icon just silence). Call for hot water does produce hot water (pump fires on, etc.) Service > Relay Test again fires up the boiler and heats up the radiant heat system until I exit service mode again.

I've checked the connections for the thermostat and they're secure. Thermostat is working correctly and calling for heat. I'm using an external temperature probe; outdoor temps are about 0 to -5C but I can't see as that could make a difference regardless.

Any suggestions? What am I missing? I've looked through the past 12 years of forum posts on the Vitodens 100 WB1B and can't find anything that addresses this issue.

Thanks in advance,
Tom
Canmore, Alberta
Canada

 

[cjg]

out door temperature probe faulty?

 

[sawback]

That could be. I'll try removing it.

 

[sawback]

It seems that the power/pump module has failed and that is the problem. Waiting for a replacement part and hope that will do it.