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steam vs hot water ?

Brad White_9
Brad White_9 Member Posts: 2,440
Big time.


  • Fred Smith
    Fred Smith Member Posts: 10
    steam vs hot water ?

    With two pipe radiators, how do you tell if you have a hot water or 2-pipe steam system?

    My radiators are American Standard with "Corto Patented 1921" cast into a cap on the bottom side of the radiator.
  • Big Ed
    Big Ed Member Posts: 1,117
    Gauge Glass

    Is there a vertical glass tube on the boiler showing water level? If so you have a steam system...

    Radiator id... If there is a vent on the radiator and its mounted near the top its most like a water system.. if there is no vent or mounted half way up , its a steam system...
  • Garret
    Garret Member Posts: 111

    Got a digital camera? Post some pictures..

    Another thing you can check... if it's steam, you will probably have traps on the return side (almost on the floor, where the water leaves the radiator.)

    Steam traps come in a variety of sizes and styles... so it's hard to tell you exactly what they look like. They're usually like a little metal bucket, maybe 3" diameter, with a cap on it that can unscrew for service.

    I believe if you have traps, the only way you'd have a hot water system is if the house originally had steam, and was converted to hot water. When that's done, folks sometimes leave the traps in place but remove the innards.

    If your boiler is relatively old, it's unlikely that that was done.
  • Brad White_78
    Brad White_78 Member Posts: 15
    I agree and

    would add that the supply piping might be larger than the return. If gravity hot water the piping will be relatively large and different for supply as for return. I am assuming you do not have a circulator nor a basement expansion tank, other indicators of a hot water system, particularly a forced hot water system.

    If you go to an upper floor radiator and there is a vent as Big Ed said, and the vent is high, small and key operated, it is likely water. Open one and see what comes out...

    If the pressure gauge reads other than zero it also probably is water.

    Traps are something to look for as posted by Garrett but it is not absolute. Some systems did not have traps.
  • Dale
    Dale Member Posts: 1,317
    Steam vs HW

    In addition to the other posts look at the controls, steam is pressure controlled, hot water is temperature controlled. Also, even very old boiler pressure relief valves are tagged for pressure, steam = 15#, hot water = 30#
  • Fred Smith
    Fred Smith Member Posts: 10
    will update

    Thanks for all the information.

    When I go home I will check and report back.
  • Fred Smith
    Fred Smith Member Posts: 10
    updated information + ?s

    I have attached 4 images to assist the answering to my post.

    Based upon previous responses to my question I believe I have a hot water system but I want to make sure.

    3778 and 3779 show the two ends of a radiator. Does the lack of traps mean that the system can not be steam and is therefore hot water?

    3780 shows the boiler which has a dual, pressure temperature gauge. The gauge shows 14 psi @ 70 degrees F. I would post a picture of the gauge but I couldn't get a good shot due to glare. 14 psi is indicative of a hot water system, correct?

    3783 shows the expansion tank?

    The house is only one floor so I do not have upstairs radiators that I can open the keyed vent on. How does the vent operate if I don't have the key? Is the vent similar to a shrader valve on bike/car tires?

    Thanks for all the help so far.

  • Garret
    Garret Member Posts: 111

    Looks like hot water to me.
  • Jerry_15
    Jerry_15 Member Posts: 379

    Sure it's hot water. Now the next spate of questions will arrive about how to get it to work properly.
  • ur system

    Your system is hot water for sure, its a replacment bolier back in the 70's... What's the question(s) you have on this system?
    You may be getting water logged tanks as the pump and bolier feed is on return side, bleeding radaitors of air? Not as often if you have copper finned tubes.
  • Fred Smith
    Fred Smith Member Posts: 10
    hot water drain instructions/names

    Here come the questions. I need to know how to purge the system of water. I have general directions for system drainage and filling/bleeding from an old Life Magazine home repair book but I am unsure of the names of the valves. If you want to write specific directions I would appreciate that.

    Please refer to the images in my previous post. 3780s.jpg for boiler, and 3783s.jpg for the expansion tank.

    In 3783s.jpg the valve leading down is the purge valve? On the cylinder end in the background is a pipe leading to the system from the boiler. I don't know where the air valve for the tank is so it won't collapse when I begin releasing the water.

    In 3780s.jpg the following pipes connect the boiler to water supply: far right, and the copper pipe in the left foreground with a valve at its base.

    I can find 3 valves on/near the boiler.

    1) a silver water spigot in left foreground attached to the return side?
    2) some sort of stick valve on the return pipe, just behind valve 1 in the image
    3) third valve or blow off on rear top of the boiler it is attached to the horizontal pipe section above and left of the green tag.

    Let me know if you need better images.
  • Charles G.
    Charles G. Member Posts: 113
    Water boiler

    1st question-- Why do you want to drain the system? The how part is easy. Why is a different matter.
    Refilling becomes a bit of a chore if you want to do it right and not repeat/create more problems.
  • Jerry_15
    Jerry_15 Member Posts: 379

    Water indeed; and while I don't know why you would want to "purge" the system, as opposed to simply draining it down, be aware that with the pump on the return side you will have to expend some energy bleeding the system before that water will go around, and not burn out the pump. The question is: Do you feel lucky?
  • Fred Smith
    Fred Smith Member Posts: 10
    why system is being drained

    I am draining the system so I can temporarily remove 2 radiators. The kitchen radiator is sitting on an asbestos tile floor that I am removing/replacing. The bathroom wall radiator has plastic tile behind it that we removed. We can't get all the adhesive off while the radiator is on the wall.

    I am going to get professional help to remove/replace the radiators and refill the system. I read "Pumping Away" and know how much trouble pumping towards the boiler can be.

    It was suggested that I could save some money if I knew how to drain the system. Either way I'm going to watch what the professionals do so I have a better idea of how it works in the future.
  • Jerry_15
    Jerry_15 Member Posts: 379

    Sounds like you're on the right track. If you're going through the trouble of removing rads you might want to think about replacing old valves at the same time. The Euro style (like Danfoss) match the dimensions and thermostatic heads can be added for not much more. Flow direction is critical if you go to this type of valve. They will chatter if wrong way. I have some good tricks to get the old spuds out of the rads fast if it will help. Good luck.
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