Is it ever a good thing when a vent is \"hissing up a storm\"?

Daniel_3

Those look like Dole 75's and they most likely, as Frank suggested, are too small. Buy the "Balancing Steam Systems: Vent Capapcity Chart" from the online store to be well versed in not only venting your mains but also the radiators. It's for a good cause. I did and it helped out greatly.

McKern_2

When I asked the heating guy if replacing the vents on the mains (which are at least 6 years old) might correct some heating problems in the building. He said the vents are working just fine—that they were “hissing up a storm” and he “could see the steam.”

Background: last week I scheduled a long overdue appointment to deal with a number of issues in my condo building--specifically, a 12% increase in fuel use from 2006-2007; 3rd floor units run a few degrees colder than lower floors—more so when the weather is mild; hissing vents scattered throughout the building; water-hammer reported in 2 units; last “annual” maintenance was at least 3 years ago—I said that I assumed the system needed to be balanced.

Coincidently, a pipe coming from the boiler developed a leak night before the scheduled appointment, which the service tech explained would need to be repaired by someone else from the company before he could do the scheduled “boiler maintenance.” The service call was rescheduled for Monday.

I was surprised to hear the work described as “boiler maintenance” as I thought our issues went beyond this—that’s when I asked about the main vents.

I’ve read enough on The Wall to know that if a radiator vent is hissing and releasing steam, there’s a problem. Is there an exception for these large vents? Am I overreacting to wonder about qualifications because my list of specific issues was translated into “boiler maintenance”? Do I want to let this guy take a shot at dealing with the heating problems on the third floor, etc., or would this just be inviting more problems?

I did some research to find a good steam service company and came up with 2 that had excellent reputations. Neither one is taking new clients at this time, but both said that we could get on their list next year if we call early in the fall. (The above company is one we have used in the past.) Can I put off everything other than the pipe repair and basic boiler maintenance until next year?

David Efflandt_2

Just a steam heated homeowner, but "hissing up a storm" and "could see the steam" sounds like pressure is too high and/or the vent has failed. Air vents on a steam system are just supposed to vent air, not steam (or water).

Have you ordered any books here, which can be very useful for figuring out how your system is supposed to work or whether it is set up properly?

Brad White_185

Mind if I vent?

A radiator vent that hisses is working too hard. I would start at the end-of-main vents- see if they 1) Exist and 2) Are they working properly by releasing air and closing upon seeing steam. Secondary to that, I would see that the operating pressure was as low as feasible, a pound or less.

A radiator vent's only responsibility is to release the air within that radiator plus the piping which serves it, not the mains.

An imbalance around the building when it once worked is usually related either to air vents (in a one-pipe system) or to traps (in a two-pipe system). Traps act as air vents initially so in a way there is a common cause.

This is not the only thing to look for but is the first thing I would approach and eliminate as a variable in concert with checking the operating pressure.

The notion that a vent "hissing up a storm" is an indicator of good performance"?

To me that is analogous to saying that having a pet buffalo with audible flatulence means that he has a good appetite.

McKern_2

(Brad) It's the end of the main vents that are "hissing up a storm." The upper setting on the pressuretrol is 2.5psi, which this guy said was "about right." FWIW--the boiler hasn't been serviced in at least 3 years, so if pressuretrols need regular maintenance to function correctly, this one could be out of whack.

Re imbalance and vents--there are hissing vents scattered throughout the building. The owner of one of the colder 3rd floor units has replaced most of his vents with verivents, 2 other units have also installed a couple of these vents. (I was under the impression that these vents are used to control overheating--which is not an issue anywhere in the building.)

(David) I ordered The Lost Art of Steam Heating a couple of months ago and it's already showing signs of wear. And, I believe I've read everything on the site regarding one pipe systems. (I even bought a "brick" last spring and should probably spring for another--maybe I can get my condo association to kick in.)

(Brad & Dave) Although I am obviously suspicious about how well this guy knows steam systems, he made this remark about the main vents with such assurance that I wondered if it was only natural for these large vents to be considerably noisier that radiator vents and, perhaps, less precise regarding closing when the steam reaches them.

Based on your responses, I'm inclined to put off everything but the basic boiler maintenance until next year when we can hire one of those highly regarded companies that I referred to.

Finally, maybe I've been in the city too long, but "buffalo" strikes me as one of the least likely words to follow "pet".

Thanks for helpful advice.

Brad White_185

In my haste

I did not see the "mains" definition, sorry.

That said, I would say that the vent installation is suspect. For example, are they held back from the end of the main and elevated at least 6 inches above them? If they are on a tee at the end (where the return drops) a slug of condensate under steam pressure makes a decent missile as far as the vent is concerned.

In other words, no point in replacing the vent if the installation promotes damage. Can you post photos?

The 2.5 PSI is way to much by a factor of, well, 2.5 or 250% if you like drama. Crank it down... you could get it to 1.5 PSI or less with a 0.50 differential I would think. A pressuretrol may get "out of whack" as with any instrumentation, but I would first suspect the piping pigtail. Blow it out, make sure it is clean and without mud. If it is iron replace it with brass or red brass. (Use a magnet- even brass will get dark over time especially in dim light.)

Vents, like your breathing, should be nearly silent. If you yourself wheezed you would do something about it. Larger capacity vents may be in order. They should not emit steam; if so they are failing to close. Failing to close works against your steam pressure and humidifies the building, like it or not. Make-up water follows with it's own negative consequences..

I would take preliminary steps before you get your pros involved, at least do those relatively inexpensive things like "documenting cause and effect" and re-piping the main vents if needed. Why not save some fuel while you are waiting for the cavalry? Even if they do ride buffalo.

McKern_2

pictures of the vents

Here are two views of those vents. If I understand you correctly, they do appear to be elevated about 6 inches and NOT on a tee. I believe that they are about 7 years old.

Someone is coming tomorrow to clean the boiler, which I assume includes the piping pigtail. Truthfully, right now I couldn't find this "pigtail" on a bet, but I watch and learn tomorrow.

The heating in the building is fairly consistent, with the exception of the 3rd floor, which runs a few degrees below the thermostat setting--more so when the weather is mild.
There are hissing radiator vents scattered throughout the building. Are these likely to be a major or minor factor in the 3rd floor problems?

Our other primary issue is cost control (+12% increase in therms/HDD from 2006-2007). I'm anxious to see if the boiler cleaning makes a noticeable difference in the gas bill.

Thank you for your help.

Steamhead (in transit)

How much pipe

do those Dole vents vent?

I bet those things are way too small.

Measure the length and diameter of each steam main. We can tell you what you need.

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EBEBRATT-Ed

The vents are piped wrong as they are all installed on tees located at the drops.

The missing plaster above the vents show the vents are leaking some steam. Rust stains on the vent nipples shows vents leaking as well.

Check the vents for proper sizing, repipe and lower the pressure.

Ed

McKern_2

the more I look at our system, the less I understand

The vents are attached to 4 pipes that rise up from a horizontal pipe that is about a foot above the floor. For pipes #1, #2, #3 in attached photo, it's about 55" from this horizontal pipe to the connection to the ~6" pipe that leads to the vents; about 45" for #4.

These pipes are 1.75" diameter (calculated this based on 5.5" circumference).

I more I look at our system, the less it seems to resemble the examples I see online. I believe my previous description about the connection was not accurate (i.e., I said that it was not connected at a "T", not recognizing the similarities between an "L" and a "T"). Here is a more detailed description: In each case, the vent is attached immediately above a 90 degree angle in the pipes. #1 and #3 are a simple "L". In #2, there is another angled connection immediately after the 90 degree connection. In #4, there are 2 90 degree connections before the "L" to which the vent is attached.

I just realized that I didn't check the brand of the vents. I'll send an update later.

McKern_3

Thank you for the information.

Will replacing the vents at their current location OK, or must they be moved? As someone else mentioned, they've been installed incorrectly.

Daniel_3

15 inches back from the end of the main and 8-10 inches up on a tee is sufficient depending on your system's pressure settings, but higher the better in all cases.

Steamhead (in transit)

1.75\" outside diameter

translates to 1-1/2" inside diameter. Are the pipes this size all the way back to the steam header at the boiler?

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Mad Dog_2

NO

Mad Dog

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McKern_3

Beats me. I'm going back down to the basement to take pictures,

which I'll post in the morning.

I'm having trouble reconciling the machine we have with the drawings that illustrate how steam boilers work.

McKern_3

\"NO\" as in \"the vents are alright\"?

To my very untrained eye, the vents don't appear to be located "15 inches from the end of the mains" which seems to be the standard recommendation.

I didn't suspect a problem regarding location until the previous post that mentioned they had been installed at a "tee." Since then, I've been comparing our system to diagrams of steam systems and I am having trouble reconciling the two.