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Question about pressure and pressuretrol from a NYC Landlord

Med618 Member Posts: 15
I'm an owner of multifamily property in NYC. All of our buildings have one pipe steam heating systems, except for one that has a two pipe steam heating system. All six story apartment buildings.

The big message in Dan's book and what I read here is that steam systems were built for 2PSI pressure. Raising the pressure won't solveyour problems. So my question then is, what is the purpose of the pressuretrol and being able to raise the pressure if raising the pressure doesn't do anything for you?

Apologies if this is a silly or basic question but my supers and our boiler mechanics don't seem to understand the concept of pressure and I'm at a loss as to how to explain it.


  • BobC
    BobC Member Posts: 5,477

    First there are no silly questions, we all had to start learning from scratch.

    A steam boiler will build steam and begin to create pressure as soon as all the available space is filled with steam and the creation of steam exceeds the condensing of steam in radiators and pipes. In the early days many boilers exploded because of excess pressure

    The pressuretrol sets an operating range for a steam boiler. When the thermostat calls for heat, the boiler starts to fire and continues until the thermostat is satisfied or the steam pressure reaches the high limit set by the pressuretrol. The boiler will remain off until the boiler pressure is below the low limit set by that same pressuretrol.

    Pressuretrols are used for different types of steam boilers and while home heating never needs more than 2PSI (and usually will be happy with less than half that) process boilers  need to operate at higher pressures. The pressuretrol is meant to satisfy the needs of home heating systems as well as lower pressure process boilers that are used in industry and manufacturing.

    It is a shame that Honeywell not seen the need to offer a lower range pressuretrol in the 0.5 to 3 PSI range but they just don't see a large enough market for it. It would also kill the sales of more expensive vaporstats.

    Hope that explains it,

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    lower range pressuretrol

    don't forget that honeywell do offer a vaporstat whose operating range is ideal for steam heating: 0-16 ounces, and would be well worth installation in your situation. for most steam systems, large and small the steam travels quicker at low pressures-about 3 ounces for my 3 floors and 55 radiators. you need a good low-pressure gauge [gaugestore.com--0-15 ounce] to be able to see what the system is doing. the main [not radiator] vents in the system must be up to the job of letting the air out, instead of paying the fuel company extra to force the air out [i have 20 big main vents].

    why not get the steamy deal of steam books from the shop here so your maintenance personnel can get up to speed. post some pictures of the piping around the boiler, if you have any water-hammer problems.--nbc
  • JohnNY
    JohnNY Member Posts: 3,230
    A pressuretrol's job.

    A presuretrol's job is to create a pressure differential which allows the system's air vents to reopen after they've been closed via a burn cycle.

    It's true that most of the scale and function of a standard pressuretrol goes unused in many applications, but the differential is every bit the business end as much as the high limit.

    By the way. I'm a New York City plumbing and heating contractor and here is a boiler installation we did this week:
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
  • Steamhead
    Steamhead Member Posts: 16,832

    is one beautiful job!!!!!!!!!!!
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • JohnNY
    JohnNY Member Posts: 3,230
    From, you, Frank...

    ...that's a compliment I value highly. Thank you.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
  • neilc
    neilc Member Posts: 2,703
    pic question


    what's the extra loop off the mudleg drain, left side, infront of and below the hartford loop, going up  high ?
    known to beat dead horses
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