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Weil Mclain and Thermoflo

KenH Member Posts: 13
Hi. I need to have my 150,000 btu steam boiler replaced.  Was looking at a Weil-Mclain unit and was told by a plumber that Thermoflo is “basically a Weil Mclain, just branded for distribution purpose”.  Anyone have any experience with either company?   Is this true? Are they the same units, with different branding?   Any recommendations or insight would be greatly appreciated. 



    EBEBRATT-Ed Member Posts: 14,534
    Yes they are the same boiler different color jacket and the Williamson is usually a few less $$

    How did your plumber size the replacement? The only way is by measuring the radiation in the house.

    Make sure the piping diagram in the boiler manual is followed

    Make sure the boiler gets skimmed

    Better not to use copper tubing on the steam lines or header
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,736
    edited February 2022
    If you do the research you can clearly see the equipment is identical. If the equipment was manufacturered by different foundries with different molds with slightly different internal design, the numbers would not come out to be identical. The difference mat be in the warranty from the Brand Name manufacturer. The warranty is a cost calculation by bean counters. A given number of failures are allowed for in the cost of the appliance. For every 10,000 units X number will fail, so add $X.00 to the cost of the unit to allow for the failures. If a warranty is 10 years the X number is lower than the 20 year warranty. So the allowance for the warranty is a higher cost to the manufacturer. That makes the initial cost for the unit a higher price. Thermoflow/Williamson will cost less for that reason along with some other cost cutting measures. maybe a less expensive LWCO control or a thinner metal used on the decorative jacket or something else. But the Cast Iron boiler is identical.

    Here are the numbers:


    Weil McLain

    Weil McLain clearly has more information on this steam boiler, but the info is identical because the boiler is identical.
    Bottom line...
    Make sure the contractor you choose follows the instructions on the near boiler piping. you can get the lower cost product installed correctly or the higher cost product installed incorrectly. The correctly installed unit will outlast the poorly installed unit.
    in particular page 15 of the IO manual has the proper piping

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics