On an inspection this morning I found an odd configuration at the boiler. There was a water heater (gas fired) tied into the boiler (oil fired) that is used to circulate hot water through the old cast iron radiators providing heat.
The water heater had two zone valves linking it directly into the output on the boiler and shared the main return line. It was not providing domestic hot water. Could this just be supplemental because the boiler is undersized?. I have never seen this done before.
Sorry but i don’t have any good pictures.
My guess is they use gas to save on oil.
Is this the same water that comes out of the taps .
If so not a good thing .
they have a separate water heater for the drinking/bathing water. This water heater is just attached to the boiler and clearly providing additional heat.
Me thinks your correct