I want to ensure I'm safe.
Is it normal to find fluctuating 12 volts when the thermostat (2-wire heat-only) is at "rest" and not calling for heat? The thermostat appears to function normally with a zone valve opening and an end switch making when a call goes out for heat.
The reason for the question is a "hot" transformer smell, similar to the old Lionel train sets as an example, that I don't recall noticing before. The thermostat was disconnected while replacing the zone valve and doing some plumbing work.
When calling for heat I'm getting 24-volt readings which is what I expect. When not calling for heat I get a 24-volt reading at the transformer and would expect 0-volt readings further "downstream" since the thermostat is open but instead I'm getting 12-volt readings.
Is that normal?
Is that a possible reason the transformer smells "hotter" than I remember?
Is the transformer just going bad?