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Over Fired Boiler Revisited

Here is an update to the post I made a while back regarding my BTU input vs boiler rated input. Gas company claims there is nothing wrong with the meter and the dials are accurate. So here's the deal. My boiler is rated for 260,000 BTU input. However, I have an adjustable valve that has been dialed up to 450,000 BTU. I had someone come out an look at combustion stats. At 450,000 they are acceptable though on the high end of all measurable stats. When dialed down to 300,000 BTU, they are still within acceptable limits, but on the low end.



My question is, what to do with the valve. It;s been over fired for at least 20 years so I don't think any damage i being done. However, I certainly don;t want to waste fuel. My suspicion is that someone cranked it up to generate steam faster. The previous owner held the tstat at 85 all the time, and right now it will certainly hit that temp in the house. So, should I turn it down to around 300,000, or leave it be at 450,000 (if it ain't broke...)?



Any thoughts? Either way seems safe with my current venting and I do use whole house hard wired smoke/CO detectors.

Comments

  • ChrisJ
    ChrisJ Member Posts: 11,978
    If

    If it was my system I would calculate how much input you need to match the connected radiation and include a 33% pickup factor.  Then I would have a pro come in and try to match the burner to that assuming its less than where it was for all this time.  As long as you have enough input to fill the radiators plus that pickup factor you can't go wrong.  You however, may have to change your venting.



    With heat and especially steam heat I feel slower is better.  Having the system run for 40-60 minutes to fill the radiators is much better than having it fill them in 15 and then cycle on pressure.



    The end result would be more even heating and lower fuel bills.  Is 260K enough for your connected load or do you need 300K?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    edited December 2013
    Rated boiler input

    Looking back at your original post, it seems that your boiler was rated at 360,000 BTU input, so I am assuming the 260,000 rating above is a typo?



    Why not try dialing back the input to the rated 360K ? This is what the boiler was designed to run and would be in the middle of the extremes of over and under firing you mentioned. It would certainly run more efficiently at rated input than it is now, being overfired at 450K. You are wasting a lot of gas running it this way.





  • ChrisJ
    ChrisJ Member Posts: 11,978
    Ah

    So 260K was a typo.

    By all means I'd adjust it to 360K per its design.  I am still curious how much radiation you have connected?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
This discussion has been closed.