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HP to LP steam conversion

jvl1 Member Posts: 11
I have a contractor who wants to replace a HP(150psi) York and Shipley boiler and boiler feed system with a LP Weil-McLain 88 boiler. The building originally had a process application as well as heating. It is now strictly a warehouse and they just want to keep building around 50F. No process left, just about 30 ceiling mounted Unit Heaters. Tried to talk end user into gas fired UH’s with no luck. What do I need to know to keep me out of trouble? Can I replace boiler and boiler feed system, change the traps on Unit Heaters to low pressure and go on my merry way? What other pitfalls should I be aware of? Does Ray Wohlfarth still read the wall? Thanks in advance for any/all help!


  • Steamhead
    Steamhead Member Posts: 16,832
    Did they have a pressure-reducing valve feeding the unit heaters? If not, make sure the pipe sizes as well as the traps are large enough to handle the load at the lower pressure.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • jvl1
    jvl1 Member Posts: 11
    Thanks Steamhead...food for thought.
  • dopey27177
    dopey27177 Member Posts: 887
    Typically process steam and steam for heating is separated by pressure reducing valves.
    So the heating side should be O.K.

    The change over will require the removal of ancillary equipment. Your best bet is to have an engineer check out what needs to be done before changing over to LPS.

    EBEBRATT-Ed Member Posts: 15,517
    Steam traps work on pressure differential so HP traps may not have enough capacity especially at warm up time.

    This (HP to LP) conversion has been done many times with no issues. With no process part of the load is been removed from the piping New feed tank and boiler

    Check you pipe sizes you will probably find what you have is useable

    As others have suggested usually (but not always) the unit heaters are fed by a PRV at LP because HP steam would make them hard to control.
  • jvl1
    jvl1 Member Posts: 11
    Thank you for the input. I have recommended that the end user hire an Engineer to assess current load conditions and piping arrangements to see if is feasible. Erin, you can close this thread. Thanks!
    Erin Holohan Haskell
This discussion has been closed.