I have a 15yo Burnham boiler, that works fine. It is rated at something like 84% efficiency. there is no damper--it is always open. there is also a cold air inlet in the room that is always open.
The boiler is getting old, and the chimney it, and the water heater vents out of is in need of repair.
I'm wondering if I upgrade to a boiler and water heater that vents out of the side of the house, if I will save a lot of energy If a newer boiler is rated at 94 percent efficiency, does that include the inefficiency off all the cold air being dumped into the house, and all the warm air escaping out of the chimney?
I am hoping the upgrade will allow me to eliminate the chimney (at least to the roof line) save me money in heating costs, and, hopefully, keep the furnace room warmer--indirectly heating the kitchen above (which is the coldest room in the house.
There is a company near me that will sell you a boiler and be a resource for you to do a self-install. I've done lots of plumbing and other home repairs, so I believe I am capable.