...and in with the new. New Bosch 150k BTU hi-efficiency boiler installed last week. Tankless DHW maintains 4gpm continuous. House is 100 years old, old cast iron radiators with a 2" CI pipe loop around the basement. So far, nice and toasty!



Also converted from oil to natural gas in the process. Old boiler was estimated to be 60 years old, made around 1956.



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Did you check the efficiency of the old unit before removal ?

No...how would I do that?

they installed an expensive spirovent air eliminator for cast iron radiators?
they installed a circulator with no isolation flanges when you have 2 inch pipe and radiators?
same goes for the expansion tank. no way to isolate it when it fails.
sorry to be critical but they waste money on an expensive air elimination device that is NOT needed and cut corners on inexpensive ball valves that would save a mechanic hours of labor.

too late now..
but it is done the same way by every oil burner tech. measure the flue gas temperature. adjust for the ambient cellar temperature and compare that number to a made up chart.

Standard flanges on the circulator, but ball valves on either side so the pump is easily isolated.

The specific efficiency of the old unit is really irrelevant because:

1) At that age, it has to be lower then the 95% efficiency of the new one;
2) We were converting to gas because wife hates the smell of oil so needed a new boiler anyway.
3) Chimney is coming out to accommodate remodeling floorplan.

i'm glad there are valves.. i just couldn't see them.
anyway, i am told that that type boiler runs at top effeciency when it is working hardest. so with big pipes and old radiators you will get the max out of it.

That's what they told me. If you follow the return pipe up and to the left of the circulator, that bump right under the main beam is one valve, the other is in the CI pipe below the circulator.

We put a Buderus in our last NY house and it ran for 16 years with no repairs and almost no maintenance. Gas burns so clean compared to oil that you don't need the annual burner tune ups and cleanings. Buderus is now part of Bosch so we went with them again.

How I knew it was time....The job had to be scheduled around the town inspector, so they started on Monday with inspection scheduled for Tuesday. By Monday evening, the old boiler was out and the new one was in, but they couldn't turn the gas on before the inspection, so they hooked up a temporary electric 5-gal 120v HW heater. I got more hot water in the shower the next morning from that little thing than I had been getting from the coil in the old boiler....so it was time.

Water feed to this system should be between the Spiro vent and the expansion tank (Point of no pressure change).Also circulator should be after the expansion tank (Pumping away as Dan says)



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NoHub, do you think that is necessary with all that water volume in that system?
i know when the circulator kicks on it can change the pressure slightly and POSSIBLY have the auto fill think the boiler needs more water. but with that much volume i don't think that is the case..