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Boiler Efficiency and Savings

So I just reread We've Got Steam Heat and want to run something by the experts to check  my math and thought process. 

I have an older American Standard boiler with an rated input of 2.0gph.  Based on that I calculate that the input is 280 mBtuh.  The Gross Output is 208 mBtuh.  Which translates to a 72 mBtuh (25%) loss leaving me roughly 74% efficiency (best case scenario). 

I currently burn approx. 1500 gallons of oil/year so moving up to an 85% efficient boiler will save me about 13% per year?  So at $3/gal I'm looking at $585 savings.

The estimates I got to replace the boiler are $7500 so it would take 10+ years to pay for the upgrade...

My boiler tech installed a smaller nozzle but I assume that it would lower both the input and output proportionally.

Am I missing something? 


Jeff in Groton, CT


  • Steamhead
    Steamhead Member Posts: 16,727
    If that boiler still has its original burner

    then the numbers are about right. It will do better with a newer flame-retention burner, but still not as good as a new boiler.

    See if the boiler is properly sized- count up the radiation load and compare it to the boiler's nameplate. If the boiler is way too big, consider replacing it now rather than later.

    Then look at ways to improve the system's efficiency, such as upgrading the air vents and insulating the pipes.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
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