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Underperforming Steam Radiators???

dcha Member Posts: 50
Noel, you've been very helpful. You should teach...


  • dcha
    dcha Member Posts: 50
    HELP: Underperforming Steam Radiators???

    I've found a lot of helpful information here thanks. But I have a very specific question. I have a gas boiler, steam radiators (single pipe). I noticed that the radiator in one of my bedrooms on the second floor doesn't heat up. The same goes for the radiator in my family room. All other radiators will be hot while these stay cold.

    So I blasted the system last night, setting it to 90 degrees. And sure enough, the ones that were normally cold got very hot.

    So those "underperforming radiators" clearly work, but won't under more normal settings (like 75 degree setting).

    Please help and thanks in advance.
  • most likely causes

    1. Lack of a large enough working vent on the steam main serving the cold radiator(s).

    2. Lack of pipe insulation on the same mains.

    3. Radiator vent not working properly to move air out of the radiator fast enough.

  • dcha
    dcha Member Posts: 50

    Where can I check for the vents on the steam main? What does it look like? I've checked the valves and the insulation is fine.
  • Locate the mains, first

    Follow the mains from the boiler end, out to where the last radiator branch pipe on this main connects to the main. Any place after this last branch (but most likely farther out) connects, there might (should) be a tee with a vent above the main someplace. Lot's of times, it is roughly 12 inches back from the place where the main turns down to drain the water back to the boiler. Sometimes, it is (incorrectly) right AT this point.

    Sometimes, there isn't one. Even worse, sometimes there isn't even a tee to put one in.

    Here's some illustrations...

    Gorton's venting illustrations

  • dcha
    dcha Member Posts: 50

    Your responses have been very helpful so far - thanks. Are you referring to the "air eliminators" in the diagram? Are these designed for steam radiators?
  • yes

    They are the same thing.

  • dcha
    dcha Member Posts: 50

    Great! I've located a local supplier. I'm going to buy #6 valves for the colder radiators, and buying #4 valves for the radiators in the room of my thermostat. Then I'm going to check my air vents tonight, and try to clean them out assuming I can locate them. Wish me luck!
  • Best of luck!

    If you find main vents, see if they blow air out of them when you first start up the heating cycle. If they don't pass air that you can feel with your fingers, consider replacing them with #2 Gortons (if there is room for them; they're about 6" in diameter).

  • dcha
    dcha Member Posts: 50

    If I follow the main lines out of my boiler, I should be able to locate them, right? Does the long main (which heats the "cold side" of my house) typically have the vent installed in the boiler room? Or should I look for it to stick out of the ground near one of my radiators on the 1st floor somewhere?
  • it'll be right on the pipe

    It won't stick through the floor, usually. It'll be right on the main pipe, wherever that pipe runs.

    It could be a small thing, like a chrome, 1.5" acorn looking thing, or similar (depending on brand).

    There might not be a main vent. On older coal-designed systems, they didn't use them, in a lot of cases. If you have two mains, it's probably new enough to use main vents, as the older coal systems had a single main running all of the way around the building from a boiler located right next to a coal chute and coal bin. These were hard to balance, once converted to an electric-controlled oil or gas burner. That's when they went to shorter, multiple mains from a centrally located boiler.

    From another post on the wall, here's a pair of (copper colored) Gorton #2 main vents.

    Gorton #2 vents

  • dcha
    dcha Member Posts: 50

    whoa. that picture helped a lot to visualize - thx. I'm in a crash course trying to learn about everything from heating to plumbing and electrical. What did pple do before the internet???
  • dcha
    dcha Member Posts: 50

    Last night, I looked at all my mains very closely, and did not find any installed vents. :( So there was no vent for me to clean.

    I went and changed my radiator valves with the Gorton #4s (in the room where my thermostat is) and put #6s in the cold rooms.

    I could be wrong, but the only noticeable change was that the radiators in my living room (where the thermostat is) heated up slower, and didn't get as hot. The cold rooms' radiators didn't show any improvement. :(

    Now I'm worried that putting the #4s in my living room is somehow making my heating system less efficient. The goal was to restrict steam flow to the room with the thermostat so that the steam had time to travel to colder parts of the house before condensing and returning to the boiler. Instead, I have no noticeable improvement in the colder rooms and the living room is probably going to take longer to heat, making the boiler work harder. Should I simply put the old valves back on in my living room? I don't know what else to do. Maybe I just have to live with those cold radiators?
  • Daniel_3
    Daniel_3 Member Posts: 543

    You don't have to live with cold radiators. If you just bought Gorton's for a few rads you should buy them for all the rads since one make of radiator vents (different orifices) is the best choice for an entire system sicne venting attributes of different makes are so different. Above all you have to vent those mains. This by far is the best solution and after that then turn to the venting needs of the radiators.
  • ttekushan_3
    ttekushan_3 Member Posts: 958
    another problem that shows up

    is settling of the house. You mentioned upstairs bedrooms don't heat well. These will be the longest runs more likely to have horizontal runs. If their pitch was marginal at the time of construction, settling can allow water to pool in that line restricting the flow. If your boiler isn't oversized you may not hear any noise in this line. If you had a giant boiler, a restriction like that would go CLANK and then quickly provide steam to the radiator.

    I've solved that problem without cutting pipes, etc. Dan Holohan has suggested placing checkers under the feet of a radiator to level it. Place them under all the feet in this case to raise it. This raises the pipe out of the floor and can often lift the pipe into a better orientation to drain the pool of water, easing the steam's path.

    2X4's and some leverage and a helper really come in handy!

    That lack of main vents is a bit of a concern but I've seen small residential heating systems without them. Things would heat more slowly, but it didn't stop a few radiators from getting hot.

  • dcha
    dcha Member Posts: 50

    Thanks for your reply. I've read about pitch problems in radiators before. One thing I'd like to mention is that only one bedroom on the second floor is having this problem. The rest are good. The one that has the problem is indeed the furthest from the main boiler, but not by much.

    When I turn up the thermostat to its highest level, the radiator that I have problems with does heat up nicely (fully). But under more normal temp settings it doesn't. Does this mean that pitch can still be the problem? I did in fact manage to fit a wooden shim on vented end of the radiator, but it was really tough. How much force was necessary to raise your radiator?
  • Let's dig deeper

    Keep in mind that if you weren't providing steam to all of the rooms before, and we manage to get steam to go to all of the radiators, the boiler has to make more steam. Since it runs at only one rate, this WILL make the cycles longer. You're heating more of the house.

    You're going in the right direction.

    It would be nice to know how much radiator there is connected to this system, to be able to compare it to the boiler output and see what the boiler is up against.

    Use the instructions for "sizing obsolete radiators" from this website (bypass the log-in). Let us know how much radiation you have connected.

  • That is part of my job

    However, it's for hot water heating, rather than steam.

This discussion has been closed.