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Radiators Hissing and steaming after insulation applied

Recently I found out my steam pipes in the basement should be insulated. So... off I went and purchased some fiberglass 3ft sleeves and installed them, but hadn't even gotten around to the T's and elbows. Well, after turning on the heat now all the radiators will hiss and release steam for the first 10min or so after the heat is turned on. And, it's really really loud!!! Can't sleep through it. I have a oil boiler and 6 radiator one pipe system with over 120 feet of pipe in my 22ft by 23ft basement. The nice side of it is I can tell the radiators are warmer and quicker to heat up. thanks!


  • More venting needed

    Hissing radiator vents are a cry for help from the system. What is your pressure in the system (a 0-3 psi gauge may be needed).

    What sort of main vents are currently installed? Pictures of them would help with the diagnosis.--NBC
  • emilyjoyemilyjoy Member Posts: 11

    I will poke around down there after work and see if I can find some sort of gauge. I was wondering if that might be the problem. Is that something that can be lowered by me? Or will I have to get a repair guy out? Unfortunately I am only free on the weekends and hate having the pay the extra hourly rate. Has anyone heard of this happening after insulation applied?

    An oversized boiler can lead to hissing sounds. It is possible that your boiler is oversized.When you add insulation to pipes, in essence the boiler is becoming even more oversized. Just a guess.
  • emilyjoyemilyjoy Member Posts: 11

    ok, these are pics of the boiler brand, the pressure gauge, and the pressure setting? The boiler was on and some of the radiators were hissing. I can only assume that the pressure should not be zero? I'm sorry these pics are bad, the basement is really dark at this time, actually always- dirt floor in a 175 yr old house!
  • emilyjoyemilyjoy Member Posts: 11
    sorry they are sideways

    here's the pressure gauge
  • kcoppkcopp Member Posts: 2,746
    edited February 2014
    sounds like.....

    you need to either add some main vents in the basement or replace them.

    They are larger than the radiator vents. Usually they are found at the end of the mains. Where are you located?

  • emilyjoyemilyjoy Member Posts: 11

    I'm in MA. If I take the insulation off, that cost me $300, would that solve the problem? how involved is adding more vents?
  • emilyjoyemilyjoy Member Posts: 11

    Should I not be running the boiler? Also, if it's ok for it to be running can I shut off the radiator in my bedroom so it won't wake me up while I wait to get it fixed. It's the end of the line on that side of the house.
  • kcoppkcopp Member Posts: 2,746
    your fine....

    You just need to go the next step. The boiler is running on low pressure , its safe. If you want to quiet the radiator then twist the air vent shut or flip it upside down. Did you check the find a contractor listing?
  • emilyjoyemilyjoy Member Posts: 11
    I have a company, thanks

    Thanks so much, I can sleep peacefully tonight! unfortunately it's just me at home, and, I gotta work so I can't be here for a repair guy until this weekend or Tuesday. I just had him out here last Saturday to repair a broken motor!! But, my oil delivery company also does service and I trust them.
  • emilyjoyemilyjoy Member Posts: 11
    vent size?

    Now that I understand what a main vent is (feeling pretty foolish), I think maybe this is something I could replace with some help. There is only one vent I found, and it has evidence of rusty water on it's sides so it may need to be replaced. How do I determine what size I should have? Here is a bad pic of the current vent. It's up too high for me to read the small numbers on the side.
  • BobCBobC Member Posts: 4,408

    That vent is probably much too small, how long is the steam main it comes off of and about what size pipe is it? From that we can calculate the volume of air that has to be removed. Also how much height is there above that vent?

    Replacing one just takes a good wrench and some teflon tape.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • emilyjoyemilyjoy Member Posts: 11
    2" pipe

    All the main pipe is 2". There is somewhere between 80-110 ft? I think it's closer to 100'. There is maybe 2" above the vent? maybe a little less.

    Thanks so much, you guys are awesome!!
  • BobCBobC Member Posts: 4,408

    If you have 100 ft of 2" pipe you have to vent about 2.2 cu ft of air, that old vent might be good for 0.1 CFM if it's working correctly. It will take 20 minutes for that vent to clear out the air and you are paying for that every time the boiler turns on. You would like to reduce that time to a minute or two and that main should be insulated.

    You should probably have 2ea Gorton #2 vents on that main. The problem is they are large vents (7" tall or so), how long is the 3/4" pipe your vent is on top of? That might be replaceable with a shorter pipe so an antler could be build for multiple vents.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • emilyjoyemilyjoy Member Posts: 11

    Thanks! It's probably about 10-12" of pipe? how much needs to be there before the vent?
  • SteveSteve Member Posts: 234

    Based on your dimensions you need a little less than 2 of the Gorton #2 vents. Over venting is fine,even preferable to be sure you are running at max ability.You can buy them here.

    You can install them with a tee fitting and couple of elbows.
  • emilyjoyemilyjoy Member Posts: 11
    another question

    My local plumbing supply place doesn't carry Gorton vents. They have Vent-rite. Are any of these similar? or is Gorton the only way to go and I should order it online and wait.
  • HoyteKingHoyteKing Member Posts: 80
    edited February 2014
    Gortons too big for radiators

    Our steam contractor Ziggy is putting on Gorton 4's and 5's (for the radiators). I was told by a very good steam man recently that Gortons are too big for radiators. He uses a different type, but did not say which one.

    Anyone have an idea? We have Hoffman vari-vents, also. They are not reliable and seem to be of poor quality. Ours are unusable after 2-3 years.

    I understand the Gortons are very good for the mains.
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