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Steam Radiators - How "Cool" (or hot)

I have a 2-pipe steam and have been in this house for 30+ years.  I've never actually known the answer to this question.

<strong>When my radiators get hot, should they be hot "top to bottom", or <span style="text-decoration:underline;">only</span> at the top?</strong>  Posts on this site sometime mention "top to bottom" and I admit I'm envious of that.  Or, are those references to hot water systems and not steam.

Somebody answer this age-old question for me..

Thanks !!


  • jpf321
    jpf321 Member Posts: 1,567
    depends on ...

    depends on what type of rad .. if you have "hot water" rads which are connected through both the bottoms and tops .. then chances are that the steam will enter the inlet and head up and across the top. there are a few old diagrams (or maybe even new diagrams) which explains what's happening.

    if you have "steam rads" which are only connected across the bottom, you should have a fuller experience (bottom to top)

    I should note that I have 1 rad that I have "fixed" as per the below article .. but i'm not sure how much it helped.. i have been meaning to do some data logging on it. .. see my thread here:

    in fact in this article here: there is the following diagram

    1-pipe Homeowner - Queens, NYC

    NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

    installed: 0-20oz/si gauge | vaporstat | hour-meter | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains

    Connected EDR load: 371 sf venting load: 2.95cfm vent capacity: 4.62cfm
    my NEW system pics | my OLD system pics
  • how hot?

    first of all, are the rooms served by these radiators comfortably warm? if so then they are probably working as originally intended. also do you have the quick arrival of steam?

    if you can cause the boiler to run continuously, by crossing the thermostat connections, then you could see if at the end of a long run, whether they would heat up completely.--nbc
  • Kentucky_Steam
    Kentucky_Steam Member Posts: 26
    More on Steam & Hot Water Rads...

    Every radiator I have is "supplied/fed" at the top of one end and "returns" at the bottom of the other end.  This is two-pipe steam (that much I'm certain of).  Does this mean I have hot water rads here?

    For 2-pipe steam, shoud these be "supplied" and "returned" at the bottoms of each radiator... to be correct?
  • Two Pipe Radiator Valves

    While there are some exceptions to the rule, on most two pipe steam systems the inlet is at the top of the radiator and the outlet at the bottom.

    - Rod
  • Jamie Hall
    Jamie Hall Member Posts: 17,776
    most radiators

    later than the teens could be used either for hot water or steam -- and they are usually fed at the top and returned at the bottom; sometimes at the same end, sometimes at the opposite end.

    It is quite normal for the radiator to heat across the top first, then start to work down.  Only if the radiator has steam for a long time will it get hot all the way across and all the way down -- say on a long recovery of something like that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 15,028
    That's a Vapor system!

    It was designed to heat on less than a pound of pressure on the coldest day of the year. This was the Cadillac of heating back in the day, and is still one of the best out there.

    Have you found any maker's info on any of the original hardware, besides the radiators?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Kentucky_Steam
    Kentucky_Steam Member Posts: 26
    original equipment

    We took out and American Radiator Co. boiler... "Ideal Redflash", back in September 2009.  House will be 100 yrs old this year and we believe the boiler was original to the house.

    I kept the pressure guage as a souvenir and have some photos of the "old man" if you'd care to see 'em.  There was no low-water cut-off on it and certainly no water feeder other than a manual valve.

    It had everything but a whistle on it.
  • Steamhead
    Steamhead Member Posts: 15,028
    edited February 2010
    How about

    on the radiator valves and traps, if any of these are original? Or any old Vapor hardware in the piping near the boiler?

    If the house is 100 years old, either the Redflash was not the original or the system was installed after the house was first built. The Redflash didn't come out until the 1920s IIRC.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
This discussion has been closed.