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How to vent 2 radiators on one pipe

Claude Member Posts: 8
I have a one pipe steam system. I noticed I had 7 pipes going up to the rooms yet I had 8 radiator. I found 2 upstairs radiators share one 1" pipe. One makes like a water boiling sound during each cycle (does not hammer at all and vents do not spit). Each radiator had a #6 vent. I thought perhaps since that pipe had more vent, that steam carried water with it as well. I changed them to #4s but did not make a difference regarding the sound, other than the radiators take a little longer to heat up. My question is, why does one of the radiators sound like it has boiling water in it (it's pitched towards the intake valve but not too much) and which vents should they have? Also, one radiator is higher that the other, the lower one has the sound.


  • Steamhead
    Steamhead Member Posts: 16,710

    there's something partially blocking the shutoff valve opening, or the horizontal run-out from the riser is off-pitch. Both conditions can trap water and cause gurgling.

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  • Tom_22
    Tom_22 Member Posts: 108
    What's the EDR of the two radiators?

    > 2 upstairs radiators share one 1" pipe.

    As far as pitch on the runout to the riser, it's said it should be pitched 1/2" per foot if it's not dripped. If that much pitch is not possible, going to to the next bigger pipe size can work.

    A 1" pipe is supposed to be able to handle 28 SF EDR. What is the combined EDR of the two radiators?

    Are they piped with a tee at the top or are they in series?
  • chuck_6
    chuck_6 Member Posts: 107

    I assume you are talking about Gorton vents (#4 and #6). The #4 should go in the room that has your thermostat. For upstairs rooms you should be using either a #6, C or D vent.
  • Claude
    Claude Member Posts: 8

    They are on a tee, then a horizontal run out to each radiator (about 12" to 18"). I'm using the MAID-O MIST vents, but I changed them back to #6s and placed a #4 in the dining room in the 1st FL where the thermostat is. I also turn the pressure down from 6 PSI to 2.5 PSI (only because of what I've been reading on this board/site). All the radiators seem to heat up fine at that pressure. I've been in this house for 10 years and never got the nerve to touch the furness until I started reading this board.
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