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Banging Radiators

Stan_9 Member Posts: 6
No suggestions? I hope this is not as scary as this makes me feel it might be ...



  • Stan_9
    Stan_9 Member Posts: 6
    Banging Steam Radiators (Somewhat long post)

    OK, I know this question has been asked many times but I am overwhelmed by the amount of possible explanations. Maybe you can help me narrow the list down. With apologies for the long post, here it is:

    I recently moved in on the third floor of a three-story building with a one-pipe steam system. The first floor neighbor wanted to relocate a main pipe in the basement as she wanted to convert this part of the basement into living space. Before any work commenced, she turned on the heat (she is the one with the thermostat) and all of my six radiators worked, with a few glitches:

    1. Two of the radiators came on much later than others,

    2. One had a notable banging noise and water squirting out of the air vent. By the way, I discovered that both steam valves (not the vents) were seized.

    3. I noticed that the radiator with the banging noise and squirting vent had the wrong pitch.

    I replaced the squirting air vent and pitched the radiator correctly. I also loosened the steam valves to the point they appear to open and close and made sure they are fully opened. The vent continued squirting over the next several days and eventually stopped. Now, the other of the slow-to-heat radiator started banging and this happens even when the radiator is not heating up (I touch the supply pipe to this radiator, it appears warm, but heat rarely travels into the radiator).

    Since the usually cold radiators do not bother us (one in the kitchen, one in a bedroom that is currently used for storage) as the apartment is generally quite warm, I stopped thinking about the issue and tried to ignore the banging issues (the rooms are farthest from the bedrooms, so the noise is bearable).

    The main pipe was relocated; I asked the neighbor to turn on the boiler (although it was a warm day) to test the results. All radiators worked, the two slow ones again with banging (and again coming on much later than the rest), no squirting this time. I figured same as before, even better.

    Now, a couple of weeks after the relocation of the pipe, the two slow radiators still bang without getting even warm, and two of the radiators on the other side of the apartment have started banging (now this is a problem, since one is in my little girl’s room and wakes her up in the middle of the night).

    In all instances, the banging appears to be coming from the steam valves of the affected radiators. Should I be replacing them? Is the new banging is any way related to the relocation of the supply pipe? Should I pitch all radiators even more (although they appear to be pitched correctly). By the way, the new supply pipe is not insulated but it supplies steam to the two slow radiators. In all four banging radiators, I suspect they are actually connected in pairs to the riser pipe (but cannot really verify this fact). Is it possible this connecting pipe is pitched incorrectly? Can I pitch it somehow without ripping floors open or tearing up the ceiling of my neighbor below? Any advice will be greatly appreciated.

  • Banging is caused

    by water and steam meeting in places they shouldn't. Since your banging is at the end of the steam main, I bet the return line that drains the water from the main has gotten plugged. This would cause water to back up in the steam main, where it would bang and interfere with those radiators heating.

    The cure would be to replace the return line.

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  • Ed_32
    Ed_32 Member Posts: 33

    Banging in a steam system is usually due to condensate pooling in the pipe or radiator, the next load of steam comes along and instantly causes the puddle to flash to steam. Maybe as your lifting one end of the radiator your also shifting the pipes below the floor, maybe try to raise the whole radiator? You may want to re post in the morning, my experience with steam is limited, the guys on the east coast are much more likely to be familiar with your problem.
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