I was called today to assist the burner repair guy with an electrical prob lem in one of the apartment houses I work in. He wasn't able to get correct voltages at one of the zone valves.
I heat my home entirely with wood, so first let me say that what I know abo ut heating systems could fit into a very small vessel. But I offered my ass istance as an electronics technician.
There was a bank of 24 volt transformers, each feeding two apartment's zone valves. And two of these apartments had no heat. He told me that the trans former was a 40 volt unit, he went on to say that it was good, and attempte d to demonstrate this by measuring across each secondary terminal and groun d. When doing this he measured 40 volts from each secondary screw to buildi ng ground. I had to look twice at this to believe it. There was indeed from each screw to ground 40 volts!
So my next best guess was that perhaps it is a 40 volt unit and with a cent er tap to case ground. So half expecting to see 80 volts across the seconda ry I read 0 volts. However I did confirm the rating on the label. It was a24 volt non tapped transformer and an ohm meter check between each secondar y terminal and ground showed infinity. And interestingly the same check acr oss the two secondary terminals showed 1 ohm.
We replaced the transformer with a new 24 volt unit and restored the heat i n the two apartments. I asked for the transformer. I may have a chance to a utopsy it after the guy shows it to his boss. Whether I'll notice anything would remain to be seen.
This problem seems to defy all logic. Does anyone have any thoughts as to w hat could be going on here? Lenny