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Uneven Boiler Output

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Jsbeckton
Jsbeckton Member Posts: 47
My ~1950s era Weil McClain gas boiler has to output headers and I have noticed that one is always about 15F hotter than the other. This transulates to the rads on one side of the house always being hotter than those on the other side.

Any ideas what would cause that?

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  • Fred
    Fred Member Posts: 8,542
    edited December 2017
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    I assume you mean two Mains (not Headers)? If so, and this is steam, do both Mains have vents on them? Is one Main significantly longer/larger than the other? Pictures of your piping would help.
  • ChrisJ
    ChrisJ Member Posts: 15,780
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    How did you take the measurement?
    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
  • Paul48
    Paul48 Member Posts: 4,469
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    As with all gravity conversions, there are balance issues. Usually it is with radiator to radiator, but that is compounded with your system because of more than one main.
  • Gordy
    Gordy Member Posts: 9,546
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    I think a determination of steam, or hot water need be answered. Could be either by description. Betting steam though.
  • ChrisJ
    ChrisJ Member Posts: 15,780
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    > @Gordy said:
    > I think a determination of steam, or hot water need be answered. Could be either by description. Betting steam though.

    I'm betting water. Steam would have to be the same temp from both tappings unless the pressure was somehow substantially different between the two to produce a 15 degree difference
    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
  • Paul48
    Paul48 Member Posts: 4,469
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    He has several other posts on here.
  • Jsbeckton
    Jsbeckton Member Posts: 47
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    Yes, it’s hot water. I am taking the measurement with an infrared gun. There is a common return but two outputs (2.5”) that are direct returns running down either side of the house.
  • Lance
    Lance Member Posts: 271
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    Some thoughts to consider. Return flow is affecting that side of the boiler. Sludge in bottom of boiler on that side. May need flushing. Wide boilers should have drain valves on both sides to permit good flushing. Burners may be dirty and output reduced or a burner tube or two may have been removed or shutoff for fuel savings. Flue passage in boiler may be partially sooted. Rare but can happen. Gas delivered is too low. Measure manifold pressure. For better accuracy, clock the meter. Design of radiation to have greater temperature drop than the other. If heat delivered to space is adequate and no flue spillage all is ok.
    Combustion test for service checking is a good thing.
    Good luck.