Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Big Mouth Vent on Main

MissButters Member Posts: 21
edited February 2020 in Strictly Steam
Back in November after having some help from you all, we realized we were missing a vent on one of our mains. This happened to be the main where there were always a lot of hissing and clanking when the radiators and convectors started heating up. So, we put a Barnes and Jones (whoops)! Big Mouth vent on, and amazingly, the hissing and clanking pretty much stopped. Recently, however, the hissing and clanking is back with a vengeance. Also, we added water last weekend to the furnace boiler, and we had to add water again today (not sure if any of this is related). Is there anything we were supposed to do to the Big Mouth vent? Does it sound like the vent has gone bad after just a few months or am I missing something? Thanks so much!


  • Fred
    Fred Member Posts: 8,542
    First, it's a Barnes and Jones Bigmouth and second, it's a boiler, not a furnace. B) It sounds like your pressure is running higher than it should. When is the last time the pigtail (that the Pressuretrol is mounted on) was cleaned. It is likely clogged and the Pressuretrol can't see the system pressure to shut the burner down when needed. Check that first.
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    edited January 2020
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24