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The thermostat and pump relay on my heating system are powered by a transformer with an output rated at 25VAC and 100VA. It has worked well for 10 years. Also note that the thermostat closes the pump relay on a call for heat. The hot water is standing by in a 50gal gas fired water heater.
Two weeks ago I installed a wirsbo 512 (same as tekmar512). It showed no time display and cannot be programmed to perform any funtions that have anything to do with timing. It will run the pump for the default on cycle about 20 min then shuts down for the off cycle even though the call for heat is not yet satisfied.
In short, it's broke!
Normally I see transformers that are24VAC 40VA. So before I land wire on my new 511 I was trying to find out if this transformer was an issue.
The broken 512 that I installed appeared to have been "out of the box" before I got it. I think it was trashed before I got it. Just trying to cover all bases though