Recently the circuit breaker for the circulation pump circuit started tripping...the blown circuit also supported the domestic hot water recirc pump, which is how I noticed something was wrong (no immediate hot water for my morning shower).
Fortunately I was able to get a service person from Northwest Mechanical out to the house on a Saturday (for a modest additional fee). I was concerned that the tech might have difficulty with the complexity of our heating\cooling system, but that turned out not to be a problem - Joel knew exactly what he was looking at and figured out very quickly what the problem was. The Grundfos pump for the buffer tank in our heating\cooling system, was oriented such that condensation was collecting in the cover plate (facing downwards); that small puddle of water eventually caused the short-circuit. Took only half an hour to diagnose the problem, remove\replace the pump, and we were back in business. It was a pleasure watching an experienced tradesman at work.
One more quick note: the original installer of our HVAC system (Mitchell Mechanical) appears to have gone out of business - I am glad we still have an experienced hydronic heating\cooling company here in the Pacific NW in case something goes wrong.