Hissing Air Vents

Joe Y

I recently bought a house with a one pipe steam heat system.
It works well and heats the house sufficiently.
There is little if any knocking or water hammer.
The air vents are all new (home depot)
The vents start to hiss as soon as the steam starts.
When the system gets good and hot they open and
close making a loud hiss then a nice clang.
Will higher quality air vent not do this ?
Also I dont know if I have vents on the mains.
Where do I look and what do they look like.
Should I be able to find them by the sound when the system is starting ?

David Kiley

home depot vents

Hmm.. I just installed one of the home depot adjustable vents myself, and also noticed the hising. It starts right away and is non stop while the boiler is on. I also wondered if this is normal, or is it just a really cheap vent.

Anyways, hopefully someone can enlighten us.

Big Ed

Home Cheap O

Cheap vents are bi-metal type vents . Yes they can make noise . I heard them make a humming noise as well , like a reed in a horn.Don't expect them to last either... It tends to pass some steam before closing..

Buy a good valve like a "Hoffman" 1A or 1B . Or a "Gorton" They both have a float to help in accidental flooding. They are a slower valve which you want on a radiator.. They seat using a metal bottle (which acts like a float ) with alcohol sealed within. Steam hits the lower section of the bottle and flashes the booze :0 in to steam , pushing out the bottom of the bottle to raise it it up to seal off the valve

"Vari-Valves" are well made but don't have a float and are too fast of a vent for a normal radiator..These use expanding bellows to seal off the valve.


You should not hear any noise within the cycle of a steam system. If you hear venting , then you need more..Knockin is steam hitting colder condensate . Lower the steam pressure ,pitch radiators , insulate the mains and add proper venting. Solves most of the problems....


Main vents are at the end of the mains just before it drops into the wet return. Could also be near the boiler if you have a dry return...Behide the wall in a finished basement... They look like a radiator vent but with a larger tap...You can tell if they need attention is the radiators heat up one after the other. If properly vented and balance all the radiators heat up at the same time and rate...

Mark Hunt

OK. Prepare for enlightenment!


Do either of you see any MAIN LINE VENTS?

If not, ALL of the system air is being vented through the radiator vents. Enter "hissing".

You need main vents. Too much air being pushed through those little "salt and pepper shakers" at the end of your radiators.

Mark H

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Joe Y

Hissing Valves

thanks for the response.
I lowered the cut in and cut out to .5 and 1
respectively.
the radiators still all get nice and hot and much
less high pressure air blowing through my
cheap home depot vents.
I ordered a couple of Hoffman 1A's
which have "6 port settings" whatever that means
so I'll give them a try.
I'm pretty sure I don't have main vents.
Any recommendations for who to call that knows what
they're doing in the northern NJ area ?

Jeff_17

There is a contractor....

listed on this site, I believe his name is Ken Secor and is very knowledgeable about steam. He is in northern NJ! Click on "find a professional" and type in your NJ zip. He should show up!

tom_54

vents hiss too

My vents hiss also. I have new mains vents less than a year old, new vari-valve radiator vents (less than 2 years old). My system is set to cut in a .5 with a differential of 1.5. Every radiator hisses in sync. Why? I took off the main vents and blew into them and they appear to be doing their job. Ideas? Is there a way to install extra main vents without any modifications to the piping? (Such as using a t, angle, and nipple?)

Unknown

Ken is with Palmer Heating

out of Rahway, NJ

Noel

Steamhead

Yes you can

install multiple vents on one main. But before you run out to buy more, measure the length and diameter of each main and post the figures here, along with the make and model of the vent on each main. We can tell you if you have the right ones or not.

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tom_54

I have

two mains. Main one is about 32 feet long and 2.5 in diameter. Main two is about 35 feed long and 2.5 in diameter. Main vent for main line 1 is a Dole #5. Main vent for main line 2 is a Hoffman #75 and two Dole #2. I have attached some pics for you to see what I have.

Big Ed

Vent noise

Pipe insulation is good .

Waiting to see from Steamheads charts if main vents are properly sized . Looks like you have more then most . Was venting noise , or a heating problem was the reason the extra vents are added ?Looks like new work.....

All radiators heat up at the same time..Good

Water level a tad too high....Drop the water down to 1/3 off the bottom during the heating season. You can raise it up near the top during the summer for better hot water if your running a hot water coil.....



Hmmm..... I'am thinking your problem maybe too much steam.? Too much fire ? How long does it take for the radiators to heat up???...Are most of the original radiators in tact ? What size nozzle are you burning in the old gal ?

Mark K

Vent Hissing

Hi,

I think that one of the main vents on my system may need replacing. It's easily accessible for me in my basement. Is that something I can do myself, or do I need a professional to come in? Also, if I do replace it myself, should I use some teflon tape on the threads?

Thanks

tom_54

Yes

The insulation and the vents are all my work. I do have Dan's book, and it helps a lot. Most of the radiators heat up at close to the same time. Except for the last ones before the main vents. They are in the same room as my thermostat and take longer to heat up and produce the most hissing noise. So if the heat was not running at all during the night and the temp in the room was at 60 it could take close to an hour before the temp reaches 63. Don't know if that's right or not.

My oil contracter confirmed that my tankless coil has a small leak so I have to flush the system and drain water off more often than I would like. The also just cleaned the burner and it's buring at 1.10 gallos/hour.

Steamhead

Sorry for slow reply

I'd vent each of those mains with a Gorton #2. This is a bit more than the amount of air in those mains, but you will LOVE the way they work.

Those Dole #2 vents look like re-badged Gorton or Maid-o-Mist #1 vents, which equal the capacity of the Hoffman #75. I'm not sure of the capacity of the Dole #5, would have to see it up close.

You could of course, buy three Dole #2 or Gorton/Maid-o-Mist #1 or Hoffman #75 vents and the necessary pipe and fittings to put on the other main, but the Gorton #2 vents should not cost much more than that and they will work faster.

www.gorton-valves.com

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tom_54

The Gorton

#2 vents are 1/2". I guess I'll have to but a fitting to reduce the 3/4" opening to fit the 1/2" vent? Is the Hoffman #75 no good?

Ken_8

Thanks!

I want to thank you all for directing Joe Y. to me. We spoke at length a few days ago and I'll see him this Monday. His situation is "classic" and should be pretty easy to figure out.

Thanks again.

Ken

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Steamhead

Venting Capacities

of the different vents are the key here. The Hoffman #75, Gorton/MoM #1 and Dole #2 will vent about 1.4 cubic feet per minute at 2 ounces pressure. The Gorton #2 will vent about 5 CFM at 2 ounces. All are good quality units, but it's important to use the right part for the job.

A 3/4" x 1/2" bushing will adapt to the Gorton #2.

To Joe Y: You really lucked out. Ken is a good steam man.

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Steamhead

Mark, it's important to use the proper vent

for your steam mains. To find out how much vent you need, measure the length and diameter of each main and post the info here, along with the make & model of the vent on each main. We can tell you what's needed.

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al leone

size of main vent

al leone

size of my vent?

I have an 1-1/4 riser toa third floor. It come off a 3'' main that goes about 10' then it branches of into 1-1/4 runs up to the same floor any idea of a size for a main vent? I think theres a Vent-Rite #1 on there now

Mark K

Leo_4

wow. am i glad i found this..

site! i recently had my boiler replaced, and have been getting some really nice hammer waking me up in the morning. i suspect its the pitch of the main nearest the boiler. a new riser was installed from the boiler, and im guessing it raised the main ever so slightly. of course, my boiler service company disagrees and says its natural to have hammer. half the main (from approx middle of 30') is pitched about 1/2", and the other half is level. i do have half the main uninsulated, as i live in the basement, but it is heated by electric as well, so it shouldnt condensate too fast. hammer problem may also be that the valve on the radiator nearest the main wasnt working, causing radiator not to heat. im assuming this is making unneccessary condensation in the line. i changed it tonight, so we will see. this brings me to my next question.

onto the air vents. i have 2, both are connected to the wet loop. one is behind the boiler about 20", on a 2" pipe, and one at the far end of the main, about 30' from the boiler, on a 2"(?) pipe. they both do their hissing dance at the end of each cycle. can anyone recommend proper sizes for changing these?

i also am considering changing the valves on each of the 10 radiators across the 2 floors. any recommendations? the boiler man recommended setting those closest to the boiler to 3, so they stay on longer, and those at the end to 7. home depot sells durst models that come in ranges of 1/8-7/8. (not even 1! how do i get to 3, or 7??) i guess ill hit the local plumbing supply for a better selection. are this mans recommendations accuate, though?

jzkpr

Also need to change my main vents....

Awesome thread with great info. Steamhead, do you have a chart posted that can assist me in determining which size vent on need on my two mains? Thank you.