Can someone explain how gas-fired boiler efficiency is measured? This is for the baseboard hot water heating system in the house. I've been at home all day this year and had the heat up so I expected a much bigger heat bill. But no -- it has been right in the middle, and I have records for the last 10 years. However, I seem to pay 50% more than neighbors in similar houses.
That suggests the heat lost through the ceiling and walls is not the major factor. So it must be going up the flue. My hunch is that high efficiency is indicated by low flue gas temperature because all the heat is being transferred to the water in the heating system. They must check the CO and CO2 content, also, as a indication of total combustion.
Can anyone fill in the details? Thanks.