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Maddening hiss. Please help

fsk Member Posts: 31
The vents (two) in question were changed to #5 gorton.They originally had #3 dole.The hissing stopped.However the radiator on the same pipes (downstairs) are now hissing.I observed that on one of these big radiators, besides the steam vent,there is air leaking from the radiator valve(should this of any concern).

The plumber changed the vents (Two vents) and the pressure guage on the furnance and charged me $15 each for the vents and $75 for the guage plus 95 labor.Total 215$.Curious is this a normal price?


  • fsk
    fsk Member Posts: 31
    Maddening hiss. PLEASE help

    Scenario: One pipe steam system, approx 1500 Sq Ft. Boiler 70+ yrs, Burner Beckett 5 years old.

    Bought this old house this summer. So this is our first winter in this house.

    The previous home owners installed two new radiators on the second floor (they had only one radiator in the toilet on the second floor previously and since the house went on sale their realtor advised them to add radiators to the two bedrooms on the second floor which weren’t there earlier.)

    Problem: All radiators heat. The ones on the first floor are comparatively bigger in size than these two new ones on the second floor.

    The old radiators doesn’t hiss. But these two new radiators hiss continuously(and loudly). They stop hissing only after about 20 minutes or so after the burner has stopped firing.

    I read Dan’s book and tried to locate the main vents but the header is covered by the roof of the basement and I don’t know if there are any vents on the risers or take-offs (as they all are hidden in the walls)

    I see that the main header is insulated. However I don’t see any insulation on the wet or dry returns (are they suppose to be insulated). One take off that I can see is not insulated.

    The vent on the TWO new radiators is of make Dole 80 made by Eaton controls, carol stream IL.

    I would sincerely appreciate if any of the pros can point out what is wrong in this system. None of the old radiators hiss, except these two recently installed radiator on the second floor. These two radiators are smaller in size compared to the old existing radiators. And I do see that the vents on them are new. These two radiators heat completely(rather get overheated)

    PLEASE help. I would sincerely appreciate it.
  • Dale
    Dale Member Posts: 1,317

    If the rads were added for a sale the piping was probably just run to the rads with little thought to venting. The noise is probably the xtra air in the risers. I guess I would look to see where the takeoff to the upstairs is and make sure there's a large main vent past it, next you could go with the larger size gorton rad vents as the riser is really adding to rad volume. At last resort, assuming the pitch of all basement mains is good, is to look at Dan's "Lost Art..." book pgs 118 and 119 and add a master vent to quickly get rid of the riser air volume. If you solve this please let us know what worked.
  • fsk
    fsk Member Posts: 31

    The piping is NOT new.Only the raditors are new.
    Reason I say this is because there is a small third bedroom (on second floor)where I can locate the raditor pipe,coming off the floor,but no radiator installed on it.So I am guessing that the new raditors are installed on existing piping.
    The house was built aorund 1920-1930.It has changed hands over the years and somewhere down the line,the radiators in the second floor were removed.

    So if we go by the assumption that the piping was there.What can be wrong? The new dole 80 valves hiss (contantly and loudly) but are not spitting water or steam.The two new SMALL radiators (the ones that are in question here)are heating completely.
  • LarryC
    LarryC Member Posts: 331
    Dig thru the ceiling and find the Main Vents !!!!!

    Home owner here.

    I suspect that the main vents are not functioning correctly and alot of the air in the system is escaping thru the two new radiator vents. Find and fix the main vents and that will probably solve the problem. Also verify the system pressure is set to turn off the boiler around 1/2 psi and turn the boiler back on around 1 psi.

    If you don't know how to do that, or don't feel comfortable doing that, call in a pro. Look for one at the top of the web page.

    Good Luck.

    Larry C
  • fsk
    fsk Member Posts: 31
    If I shut off these two radiator there is no hissing.

    I ran this simple test to validate if the system has eccess air and that the main vents are clogged or they dont exist.
    I shut off/closed these two new small radiator.I was hoping that some other vents shall hiss and let the air escape,but all other radiators are still heating and not hissing.
    I am helpess.
    PLEASE advise..what you guys think.
    I called in a pro he looked around, checked the pressure on the honeywell control and set it to cut off at 2 psi.He said the new dole 80 vents are faulty.I dont agree with him.As if they were, than these two new radiators wan't heat.Or the very least,the vents shall spit water or steam.All they are doing is letting air out.If I put my finger around the vent the noise stops.I also checked and verified that these two new radiators are crorectly pitched.It has shims on one side.
  • Howard Emerson
    Howard Emerson Member Posts: 111

    Until you get the definitive answer to your problem, you might want to save your sanity a bit and wrap a piece of foam rubber around the air vent openings with some wire.

    If it's just air, this should quiet it down quite a bit. If it's water vapor, though, it might act like a sponge and start dripping........in which case, never mind.

    Just a thought.

  • fsk
    fsk Member Posts: 31

    Good idea.
    However I would like to hear from anyone who had ever encountered this/simililar problem or just from a technical prespective a realistic reason of why this is happening.
    All the pros who areo nline please provide your valuable two cents..
  • brucewo1b
    brucewo1b Member Posts: 638
    If you want

    to verify whether it's a vent problem or other problem change one out with a simalr sized radiator on another floor and see if it acts the same way or if the radiator does tha same thing with a different vent.
  • Tim Gardner
    Tim Gardner Member Posts: 183

    I would first the pitch on the hissing radiators. If they don't slope toward the pipe put checkers under the far legs so that they do.

    If that is not the problem, I'd try a new vent or switching the vent with another radiator.
  • fsk
    fsk Member Posts: 31
    How easy it is to

    Change vents.What tools I need?I have afraid of not sealing them properly and than maybe water or steam starts leaking.What you guys think?
  • fsk
    fsk Member Posts: 31
    ANy more

    > Change vents.What tools I need?I have afraid of

    > not sealing them properly and than maybe water or

    > steam starts leaking.What you guys think?

    Input/thoughts on this..please do reply..thank you.
  • Tim Gardner
    Tim Gardner Member Posts: 183

    The vents on my system have 1/8" threads. I tighten them by hand and maybe a bit tighter with a wrench but not too much as they are easy to break. If you need to use a wrench to get them off, just make sure you have plenty of room to work and be sure to unscrew them in the right direction. They unscrew in the same direction a bolt unscrews from a nut where the head of the bolt is the valve. Be gentle.
  • P.S.....................

    If your gonna do that,be sure the steam pressure is OFF, you may get burnt! Maybe wear a pair of gloves too.
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