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  1. #1
    Join Date
    May 2010
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    33

    Manual J results create a dilemma

    Hi. Im in NY and just was given the results of the Man J. The heat required is 46K btu for my house which is 3000 sq/ft (house is pretty tight insulation wise). Unfortunately, I cant seem to find an oil boiler that is close to that small and the contractor just wants to throw in the smallest he can find which is 74k btu. Gas is not available in my area. I was told I could go with 74k btu and have a smaller nozzle installed? Is that an option or will I have problems with that option? I dont want the boiler to short cycle either because it is much larger than required? Are there any reliable oil boilers that small? Thanks.

  2. #2
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,082
    Doubt you'll find anything really smaller.
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  3. #3
    Join Date
    May 2010
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    33
    Will that nozzle mod work or am I asking for trouble?

  4. #4
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    You can only decrease so much. And then you lose efficiency.

    What kind of hot water heat, radiant, baseboard, hydro coil, etc?
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  5. #5
    Join Date
    Oct 2010
    Location
    AZ
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    646
    You could always just open a window.

  6. #6
    Join Date
    May 2010
    Posts
    33
    I have Hydro-air and I would prefer not to open a window. lol I heard that I could reduce by 10% with smaller nozzle. Is that true? Any other manufacturers that might have anything smaller?

  7. #7
    kenney t Guest
    how about a small three pass design?

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,082
    If not done right. That 10% reduction in nozzle size can cost you a lot in excess oil use, and in increased cost of cleaning the boiler.

    What brand and model boiler was quoted to you.
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  9. #9
    Join Date
    Sep 2002
    Location
    Northeast Ohio
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    4,842
    That's an impressively low btu requirement for a 3000 sq ft home in NY. Maybe an oil fired hot water heater instead. Did run across one rated at 48,000 I.B.R. btus with an afue rating of 87.5%
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  10. #10
    Join Date
    May 2010
    Posts
    33
    The boiler that was spec'd for the house was the Burnham mpo-iq. Smallest unit is about 74k btu net I believe iq-84. I was looking at the Biasi B-3 which I think is 58k gross. Also, If I do get a boiler that is smaller will my 50 gal amtrol indirect water tank recover fast enough?

  11. #11
    Join Date
    Sep 2006
    Posts
    1,253
    Quote Originally Posted by farfigngn View Post
    Hi. Im in NY and just was given the results of the Man J. The heat required is 46K btu for my house which is 3000 sq/ft (house is pretty tight insulation wise). Unfortunately, I cant seem to find an oil boiler that is close to that small and the contractor just wants to throw in the smallest he can find which is 74k btu. Gas is not available in my area. I was told I could go with 74k btu and have a smaller nozzle installed? Is that an option or will I have problems with that option? I dont want the boiler to short cycle either because it is much larger than required? Are there any reliable oil boilers that small? Thanks.

    First thing I would do is check and double check that Man J and make sure it is as accurate as possible. If you find that it is correct you may then want to find installers in your area are familiar with the Baisi 3-pass line. They have a small boiler that has a 58K IBR rating with 87% AFUE rating.

    http://www.qhtinc.com/pdf/b10final.pdf

  12. #12
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,082
    Quote Originally Posted by farfigngn View Post
    Also, If I do get a boiler that is smaller will my 50 gal amtrol indirect water tank recover fast enough?
    Fast enough for what?

    For average shower use, or to fill a hot tub.

    A hot tub, no.
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  13. #13
    Join Date
    Aug 2007
    Posts
    971
    Quote Originally Posted by heaterman View Post
    That's an impressively low btu requirement for a 3000 sq ft home in NY. Maybe an oil fired hot water heater instead. Did run across one rated at 48,000 I.B.R. btus with an afue rating of 87.5%


    Why not? I like that idea too.

    http://www.bockwaterheaters.com/Prod...Savr_09-07.pdf


    Expect nothing, yet expect the unexpected.
    Press on Regardless, Endeavor to Persevere.

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