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Top floor apartment steam risers, help pls!

designed24designed24 Member Posts: 2
edited May 3 in Strictly Steam
Hi everyone,

I'm on the top floor of a 7 story building. Single pipe steam heat system. The risers all have straight Gordon No C. on the top but it hisses Incredibly load... as a temporary fix I cut an old tshirt into little ribbons and tightly wrap it around the hole and it shut them up while still providing heat. However the pipes bang hard for like 30 seconds each cycle start.. then its pretty quite until steam gets to very top and a loud annoying CLICK shuts the vents. This repeats every cycle.

From reading Gortons website No C's look to be designed for Radiators not Risers and I probably need more venting. I've asked my super about the boiler pressure already, he tells me it's set to the absolute lowest setting but the boiler is way too big for the building. He also said everyone below me closed up there radiator so i'm getting all the release.

Gordon No 2 look most appropriate however the problem is they would not fit since 1/2. Do you think I would be okay installing the straight Varivalves? They seem to let out a lot of steam and are 1/8. I heard some folks suggest they might have leaking issues, but is that more for the radiators? I have 5 risers total and only 2 radiators (both of which I keep off) they also have No C's angled and are loud when on.

Curious to hear your thoughts, THANK YOU! Andy


  • nicholas bonham-carternicholas bonham-carter Member Posts: 8,127
    Loud hissing indicates over pressure to me.
    Probably the pigtail on the boiler is clogged, and preventing his “low settings” from being achieved. The super needs to do some regular maintenance. He should also read one or more of the steam books available on this site, as it must be wasting lots of fuel, (for which he does not pay!).
    If you increase your radiator venting, it will no doubt be even louder, when it closes; until the pressure is properly controlled.—NBC
  • Joe_DunhamJoe_Dunham Member Posts: 32
    1- Of course it is possible that the boiler pressure is too high. it can be very difficult to modulate a burner to maintain 1.5 PSI. A vaporstat may be better than a pressurtrol (it only goes up to a few pounds and allows fractional adjustment) But the burner may still not cooperate.
    2- If the boiler has been replaced, it may have been the time to add a boiler feed pump to handle the wet returns (drip lines at main ends and sometimes every riser) Without a feed pump the condensate must rise above the Harford loop to get back into the boiler. This can block or partially block supply take offs (from the main to the risers) with condensate creating noise, distribution problems and the temptation to raise pressure. This is especially true as pressure goes up. With a feed pump, you add a float trap to the drips, and they then go to the Feed pump, You would pump into the loop when the boiler needs water. It also maintains more stable water level in the boiler because the feed pump is smart to boiler water level requirements. A water feeder is not. A feeder may even cause the boiler to flood because it feeds, and then when the condensate eventually gets back, there's too much water. The water winds up in the system. The Feed unit acts as a place where the condensate level can fluctuate. This is especially important with newer boilers because they hold a fraction of the water of older ones.
    3- Basement vents are important and should be large. Get the air out of the mains quick. Some people double them up. This lessens the load on radiator vents.
    4- Unfortunately for you, the top floor radiator vents are important to insure the whole riser gets hot. If the Super is wise to this, he may tend to the top floors and not so much the others. This puts the burden of venting most of the air at the top. If people below you are too hot, they will close the valves and cut-off or reduce the venting. And by the way, with one-pipe, the valve needs to be fully open or fully closed. This is because condensate goes back out the way it came in.
    5- The building may benefit from thermostatic venting of radiator vents. Research that. They go in line with the vents. It gives people control so they don't constantly open and close the valves.
  • STEAM DOCTORSTEAM DOCTOR Member Posts: 1,145
    Seems like there are two problems. Hissing and banging. Hissing can be caused be a leaking air vent or by inadequate venting. Or excessive pressure. Or maybe by some other things. Banging can be caused by a lot of things. Well not really. Banging is probably caused by excessive water. Excessive water can be caused by a lot of things. There are lots of variables. The only real solution is to have someone put eyes on the ENTIRE system and figure out what's going on. There is a limit to what you can do from your apartment.
  • STEAM DOCTORSTEAM DOCTOR Member Posts: 1,145
    The cause of the problem and the symptoms, are not always in the same place. Actually, they rarely are.
  • designed24designed24 Member Posts: 2
    Thanks very much for the color. I'll share this info with my super. So in summary, very little to do with the vents on my end.
  • dopey27177dopey27177 Member Posts: 286
    A Gorton C Vent vents a lot of air. It vents 2.6 CFM. If the steam pressure is to high this vent will be noisy.

    Ask the the super what is the operating steam pressure,
    In many buildings the steam pressure never exceeds 2 PSIG.
    The control for the operating steam pressure is a vapor stat.
    This control will cycle the boiler.

    The setting should start at 2 PSI shutting the burner with a 1/2 lb. or 8" differential which will start the burner to produce steam.

    What is important is the short off time in the heating cycle. This allows the vent valves to empty any water collected in the valve and also preventing a vacuum from forming in the radiators which can cause the condensate to flash into steam and cause banging, additionally, the vent valves allow air into the radiator which allows the condensate to drain from the radiator. When the radiator is free of any condensate steam will not meet the water and cause banging.

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