One Radiator hissing

CamAid

So I have one radiator that I have a Gorton #6 Vent on. Whenever I need to put the heat on for a while (say from 60 to 70) the vent hisses like its not closing. I replaced with another Gorton #6 and it didn't change. The Rad is pitched in the proper direction, Valve is opened all the way and no hammer. This is on the 3rd floor. The run in the basement also feeds 3 other Rads and they don't have the same issue? Also a second question. Can a Riser go straight up from the basement directly into the shut off Valve or does it need to have a 90 with a small nipple or branch before it goes into the Valve? Reason I ask is this Rad use to have a 90 and then maybe a 10" pipe before it went up into the valve. I was able to sink the radiator back in the wall (I boxed the wall) and now the riser goes directly into the shut off valve?
Thanks for your input.

CamAid

Oh also the pressure setting is under 2lbs

BobC

Does that radiator get fully hot? If it doesn't then steam may never get to the vent so it won't shut off.4

Bob

CamAid

It does get hot, just doesn't shut? Odd Could one Rad get wet steam even though the others on the Run don't?

ethicalpaul

But does it get “steam-hot” all the way to the vent? I would bet not—I can’t think of what would prevent a good valve from closing other than it not getting to temp. How long is the run cycle typically during this behavior?

Three stories is a lot of pipe to get to 212f. Until it’s that hot the entire length it will be condensing some steam which will keep the pressure down.

See if the valve is actually “breathing” in and out rather than blowing the whole time. To me, that is steam advancing, then condensing in a two-steps forward, one step back way

KC_Jones

CamAid said:

(say from 60 to 70)

Don't do this. I wouldn't ever set back more than 3°. This is part of your problem.

Yes one radiator could be getting wetter steam, or the pipe is condensing excessively and the water is getting sent into the radiator. There are any number of possibilities. I've seen this phenomenon on my own system on a few occasions. My system piping is less than ideal and essentially undersized so I know that's my problem.

neilc

what do you have for main venting in the basement?

CamAid

I have a large Gorton #2 @ the beginning of the dry return and then a smaller vent above the Hartford loop. I don't like this setup. The way the main pipe leaves the boiler is up-pitched for the 1st section that the condensation has to work like a counter flow system until it gets under the main beam then it goes up a couple 90's before the pipe pitches down where the risers connect and finally a dry return.

neilc

where's the tall riser in that scheme?
could you sketch a diagram? or pictures?

CamAid

acwagner

Did the new Gorton vent hiss immediately after you installed it or did it take a few cycles?

CamAid

Well I can hear it breathing but haven't had it run long enough to duplicate the long hissing or the smell of some kind of oil or pipe dope I smell when its running hard. Everyone I know drops the temp down to 60 at night/sleep or during work and 70 when home. One person mentioned only a 3 degree fluctuation? Is that only with steam ?

KC_Jones

CamAid said:

Well I can hear it breathing but haven't had it run long enough to duplicate the long hissing or the smell of some kind of oil or pipe dope I smell when its running hard. Everyone I know drops the temp down to 60 at night/sleep or during work and 70 when home. One person mentioned only a 3 degree fluctuation? Is that only with steam ?

People that do large swings like that usually have forced air, hydronic heating systems are different. The radiant energy heats the building, not the air in the building. When you do drastic set backs like that the building can cool excessively and you lose all the heat the building has and then, when you return, try to heat it back up. If you were gone for days, sure cut it way back. Under normal circumstances cutting back more than 3 degrees or so doesn't do much if anything for you. Basically you sacrifice comfort for virtually zero energy savings.

Enjoy the comfort and don't do massive setbacks.

nicholas bonham-carter

You may think the pressuretrol is set for a low enough pressure, but they are so inaccurate, that it helps to have a gauge capable of showing ounces of pressure. This would also show how good your main vents are. The main vents should let the air escape at less than 2 ounces.—NBC

acwagner

Here's a simple thing to try: take the vent off, take it to a sink, and rinse it out. It's possible debris was blown into the vent, and that is preventing it from sealing completely. I've had it happen on my system, but I found Gorton vents are less susceptible to debris clogging than other styles.