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Steam convector hammering

Hey guys, I have a Burnham IN8, year 2021 (oversized?) with 2 mains (1st main is 50ft with a Gorton 1 and 2nd main is only 18ft so I don't know if it has a main vent cause the piping is enclosed within the wall) which is for a 2 family house in NYC. I have these 2 convector heaters on the first floor that constantly hammer for a short duration upon the initial start up of each cycle. The convector in the bedroom which is closest to the boiler runs a Gorton 4 and the convector in the living room runs a Gorton 5. Both of these convectors have good tilt on them. I'm wondering if it's possible that the flame is too high on my boiler causing the hammer? Also, I have one pipe that goes to the second floor which is the last pipe on the 50ft main and it splits into two radiators, I'm wondering if this is working correctly since the other radiators only have 1 pipe to them? Thanks, any help is appreciated.


  • Jamie Hall
    Jamie Hall Member Posts: 20,416
    Pitch on the pipes leading to the convectors. Or, more accurately, inadequate pitch on a section of pipe. Doesn't have to be long.

    On the second floor radiators, the question isn't the piping, the question is do the radiators heat? if they do, they're working, eh?

    The "flame" in the boiler has nothing to do with it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,041
    edited November 2022
    As Br. Jamie says, the hammering is caused by condensate countering the flow of steam. You can handle the condensate better with bigger or better pitched pipes, or you can slow down its creation by insulating the pipes or slowing the radiators' venting. Those are about your choices.

    Make certain your steam is as dry as possible by having a clean boiler with proper piping and proper steam pressure.
  • neilc
    neilc Member Posts: 2,084
    do you have supply valves on the hammering convectors?
    and are they open? all the way open?
    known to beat dead horses
  • c_henry
    c_henry Member Posts: 5
    edited November 2022
    Yes, all the supply valves are fully open. All the pipes in the basement are uninsulated as I think they're suppose to provide additional heating even tho there is a hydronic heating system for the basement which hardly turns on, I've tested the pH of the water and it's 7. 
  • c_henry
    c_henry Member Posts: 5
    I adjusted the gas valve today from 5WC to about 3.1WC and I noticed significantly less hammering from the 2 radiators but can still hear a tiny bit of hammering and bubbling/boiling sounds from the vent. Does reducing the gas valve output reduce the BTU output of the radiators?
  • c_henry
    c_henry Member Posts: 5
    I noticed today that after the boiler finishes it cycling and cools a bit, I can hear a pinging sound like the metal is contracting because it's cooling off, is this common?
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,041
    edited December 2022
    All steam pipes should be insulated. Expansion noises are very common on convectors. Sometimes slips of plastic, like a cut up milk bottle or blocks of wood placed where the heating element contacts its supports can abate the noise as it moves against its mounting.

    Lowering the gas pressure to 3.1 is outright dangerous.

    It can cause the burner to produce substantial amounts of carbon monoxide that can, under some conditions kill the residents, as it upsets the gas/air mixture. You must follow manufacturer's gas input recommendations precisely, and shouldn't mess with the mixture unless you have combustion analyzing equipment to measure oxygen, carbon monoxide levels and combustion efficiency.

    Reducing the gas input will lower the heating output. It will also lower the boiler's efficiency. That's why it reduced your hammering.