Boiler turning on at random times
My wife and I just purchased our first home and we're trying to make sense of our heating system.
We have an oil fueled boiler which runs a heat exchange through a water tank. Heat is generated through water pumped to baseboard heaters. I suppose this is a pretty typical system setup.
When we moved in, we kept hearing the boiler go on at random times, and I attributed it to the water tank regulating it's internal temperature based on it's own thermostat. (We moved in in the summer, and the house heating thermostat was completely off).
As an experiment, I turned the thermostat on the water heater completely off. However, we kept hearing the boiler go on! I can't really imagine why this is happening, but my best guess is that the boiler itself has to maintain some kind of internal temperature?
I was hoping someone here would have an easy answer as to why our boiler is going on when nothing is calling for heat. It's no big deal, but we'd really like to conserve oil at least in the summer, when the boiler doesn't need to be on except for minimally warm showers.
Thanks very much!