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Pressure Setting For Undersized Boiler

versh
versh Member Posts: 5
Radiators in bedrooms on far ends of house on second floor are not getting sufficient steam. I have a Weil-McLain PEG40 (installed Jan 2004) gas-fired steam boiler, servicing an 8 room Colonial (7 radiators on first floor, 8 on second). Output is rated at 325 square feet. New heating expert measured my radiators and advises that I need a minimum of 450 square feet. Current pressure control setting is 2. Installer (from 2004) now advises to raise pressure setting to 3 or 4. Any risk in trying this ?

Comments

  • Steamhead
    Steamhead Member Posts: 15,657
    It won't help

    the undersized boiler will never reach pressure. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Jamie Hall
    Jamie Hall Member Posts: 19,966
    not only will it not help

    it might make things worse.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Insulation

    If you have non insulated steam pipes, risers and mains, going to the radiators you probably want to insulate them.  It won't fix an undersized boiler but having insulated piping will put more steam in your radiators. Just a thought.
  • versh
    versh Member Posts: 5
    For what it's worth ...

    ... the Weil-McLain engineers (as reported to me by Mary in customer support) told them that it would do no harm to raise the setting to 3 or 4. Why do you think it might hurt ?



    I agree about the insulation ... I've insulated all the exposed pipes in the basement as best I could with fiberglass from Home Depot ... strictly an amateur (me) job, though.
  • versh
    versh Member Posts: 5
    Insulation

    I agree about the insulation ... I've insulated all the exposed pipes in the basement as best I could with fiberglass from Home Depot ... strictly an amateur (me) job, though. Even so, it's made a noticeable difference. I would think a professional job would be even more effective.
  • Unknown
    edited November 2009
    2 PSI Max.

    Steam actually travels faster at lower pressure than high. However in this case pressure has nothing to do with it.  Think of your boiler as a pot of water on a stove. The difference here is that  a residential boiler burner is non adjustable. It is either on or off.  If we turn the burner on, it makes steam but if doesn't produce enough  volume of steam  to satisfy our steam requirements, we can either make steam faster by getting a bigger burner (This choice is limited as the burner we are using now covers the bottom of the pot ) or  we can get a bigger pot  AND a bigger burner with will produce the volume of steam we need.  What we require is volume, pressure has nothing to do with it. We will only get pressure in the system if there is a surplus of steam meaning the system isn't able  use the full amount of steam we are producing or we contain the steam in the  pot with no exit for the steam thereby producing a "surplus" of steam.



    You never want to raise your system's pressure above 2 PSI and lower  = better (per the first sentence above)  You mentioned that the Weil-McLain engineers said that no harm would come of raising the pressure .That is true for the boiler as the safety won't blow till the pressure reaches 15 PSI however if you run the system at a higher pressure than 2 PSI, you'll destroy your vents and as was mentioned it'll never build pressure anyway.



    Steamhead, who answered your question above, is probably one of the best steam pros around so I would take what he says very seriously. If you don't have them you might want to get a couple of good steam books which are available on the site. The best "bang for the buck" is the "Steamy Deal"

    [url=http://www.heatinghelp.com/products/Super-Deals/14/129/A-Steamy-Deal]http://www.heatinghelp.com/products/Super-Deals/14/129/A-Steamy-Deal

    After reading the books you'll be able to properly evaluate your installer's ability.



    You didn't mention whether it was a one pipe or two pipe system. Perhaps using TRVs you could just heat the rooms you were occupying.

    - Rod
  • Making that boiler work

    If it is two pipe you will need to throttle the inlet valves to the radiators that are heating to push steam over to those that are not heating.  If it is one pipe, use adjustable radiators vents and reduce the venting rate on the radiators that are heating to push steam to those that are not.  Vent the mains well and if the boiler has enough capacity to meet the heat loss of the home, you shouldn't have any problems if you don't use setbacks. 



    Boilerpro
    The Steam Whisperer (Formerly Boilerpro)

    Chicago's Steam Heating Expert





    Noisy Radiators are a Cry for Help
  • versh
    versh Member Posts: 5
    Thank you ... and another question

    Thank you to all -- Steamhead, Jamie Hall, Rod, Boilerpro (and anyone else that may eventually weigh in).



    I am blown away by the response -- truly appreciative and grateful !



    One other question (for now at least): How do I identify if my system is one pipe or two pipe ?
  • Steamhead
    Steamhead Member Posts: 15,657
    That's easy

    how many pipes are connected to each radiator? Two, or just one? 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
This discussion has been closed.