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Too hot

Greetings!, I have a one pipe steam system in a 1.5 story home. The biggest radiator in the house is in the master bedroom on the second (half) floor. I wanted to be able to have more control over it so I removed the "Homart 775.8812 Air Valve" and replaced it with a Honeywell TRV. I have the TRV set to it's coolest setting and still can't get that radiator to cool down. Any ideas? I've thought about shutting that radiator completely off but the only other radiator on the top floor leaks from the valve so I have already shut that one off.


  • FJL
    FJL Member Posts: 354
    Near a Draft?

    Is the TRV by a window or near a place that is drafty? If the TRV is near a draft, it can sense cold and allow steam to enter the radiator.
  • nicholas bonham-carter
    Overheating upstairs

    If the valve of the other rad is leaking, it's time to fix it. While you have got your dirty clothes on, check out the pressure in the boiler. Most steam systems function better with low pressure, such as 6 ounces max. Learn how to adjust your pressure on the pressuretrol, and get it as low as possible. Under excessive pressure, the steam is hotter, leading to harsher, hotter rads, with leaks. Unfortunately, the standard 0-30 psi gauge is useless for diagnosis, and only there for code requirements(also to show you when it is time to cut the boiler off and leave the house quickly!). Get a 0-3 psi gauge and put it on in addition to the 0-30, so you can see when you are burning money.

    I would think that the radiators in your house were correctly sized for the rooms they are in, and so with a properly maintained system, they should be comfortable. Trv's are a last resort for over-size rads, where the window will not be opened.--NBC
  • Aberagejoemn
    Aberagejoemn Member Posts: 40

    Thanks for the replies, first I'll answer some of the posed questions:

    Yes the rad is near a window, however the windows are maybe 3 years old so I doubt the TRV is opening due to a draft, the room and area near the rad is very very warm (80s+). Also this room (and the house) were insulated 3 years ago with noise proofing insulation, I live near the Minneapolis airport. So if the rad was originally sized for the house/room the insulation and new windows should make it that much more efficient.

    So while the boiler was running this afternoon I checked the 30lb gauge and it was at about 1-2lbs, and from what I've read that should be the target area, feel free to correct me on that. The boiler is new as of 2009, it's a Burnham.

    Some additional information:

    All the radiators appear to be original. There are misc air vent brands on the radiators. There are problems with a number of radiators:

    The bathroom radiator valve leaks/drips when the system is on.

    The radiator near the front door does not heat (this is probably the radiator closest to the boiler). I'm not sure if it's because the air vent is clogged and won't vent or if the valve is closed on it. I've tried gently to open the valve but it won't turn. I'm hesitant to put a wrench on it during heating season.

    And then as mentioned before the only other radiator on the second floor we turned off because it was leaking at the valve.

    My better half won't let me replace any valves during heating season, but I did see some at Home Depot, I believe they were 3/4" valves. Are all the valves the same? or are they sized with the piping? I'm tempted to try to replace the upstairs one...

    I also picked up a couple Maid-o-mist air vents from Home Depot as backup. And then I have one other used adjustable vent from Hoffman that I found at a salvage place.

    We also have water hammer at start up, probably 10-15 minutes after the boiler kicks on. The pipes in the basement were at one time insulated with asbestos but that was removed before I bought the house. I insulated the pipes with what Home Depot had, it isn't the best stuff but I have to imagine it's better than nothing.

    Any thoughts?
  • Jamie Hall
    Jamie Hall Member Posts: 23,415
    Can't say I blame her...

    if the house is warm (or too warm!) replacing valves -- unless you know what you are doing -- is probably not recommended!

    Besides, almost all your issues are a matter of venting, from the sound of it.  There are vents -- and then there are vents.  The vents which are available from Home Depot and the like are, I am sorry to say, not very good.  There are other brands which are much better; a lot of folks seem to like Gortons.

    Venting comes in two stages: first, it is necessary to get the air out of the steam mains as fast as possible.  For this you need vents on the mains themselves, down in the basement.  You may or may not have them.  If you don't, you'll be much happier after you have figured out how to add them.  Once you get that done, then you can add good adjustable vents to the radiators, and adjust them so they heat the way you would like them to.  Takes a little fiddling, but it's not hard (usually!).

    Your pressure is OK.

    The leaking valves can sometimes be fixed simply by tightening up the bonnet slightly.  If that doesn't do it, they can often be fixed by replacing the packing on the valve stem.  Do NOT try to use "looks like" valves from a big box store.  Radiator valves are matched to the radiators, and are built somewhat differently.  Yes, they are more expensive -- but they work, and the "looks like" ones don't.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Aberagejoemn
    Aberagejoemn Member Posts: 40
    edited February 2012

    Almost forgot and not sure if this is helpful but when the radiator in our bedroom is hot and the boiler is on at first the air vent on the TRV will vent the air inside the rad, then when it gets hot it will close. But after a while, the vent on the TRV will open and spew out like a hot tea pot, close again, and repeat. I don't have specifics on how often or for how long it will do this but I thought I'd add. I'm thinking I should get some photos/videos.

    Here's the new TRV:

    Here's the radiator, we put the fan in front to blow some of the hot air out of the bedroom and into the hall. The radiator is huge, double wide and length at least:
  • Aberagejoemn
    Aberagejoemn Member Posts: 40
    More photos

    Here is the rad and TRV
  • nicholas bonham-carter
    Overheating rad

    Take off the trv's, and replace it with the original valve mounted upside down, which will close it and prevent it from releasing the air (at least Hoffman does this). The rad should now see no steam, and become cold.

    I would replace/install main vents, and with an accurate low pressure gauge, reduce the pressure as much as possible. 1-2 psi gives basic functionality, but for comfort and economy, you only need 2 ounces! At these pressure, you will need extremely generous main venting with a back-pressure of only an ounce or so, and you may need to switch to Hoffman 40 radiator vents.

    I know it seems impossible to heat a building with less pressure than it would take to blow up a ballon, but it is true!--nbc
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