Air vents hiss whenever boiler is working

heatinghelp819 · January 2017

Hi everyone - I have a steam heat system. A few weeks ago, we had some work done on two radiators that were leaking and losing lots of steam from the valves. The valves were replaced and leaks fixed. Since then, most if not all of the air vents on our home's radiators hiss whenever the heat comes on and the boiler is cooking. This had not happened before. The pressure is set to the lowest possible setting (I think) and doens't look high when the boiler is running. Some of the air vents are brand new. I'm not sure why this is happening. My only guess is that whatever is now escaping the air vents had previously been leaking out of the two leaky radiators, and now the weakest point is the vents. But this doesn't sound right. Any thoughts? Thank you!

Abracadabra · January 2017

What is the pressure gauge showing for pressure when radiator vents are hissing?

What do you have for main vents?

Fred · January 2017

Could also be coincidental to the leak fix. If it didn't happen before, also take the Pressuretrol off of the pigtail (looped pipe) and make sure that pigtail isn't clogged. If it is, it won't let the Pressuretrol see and manage the system pressure.

New England SteamWorks · January 2017

Your guess is probably correct. And just as likely, your main venting is inadequate, which is forcing the poor radiator vents to do all of the venting, and they're mad about it.

Which is why they hiss.

heatinghelp819 · January 2017

Thanks all.

I just upped the thermostat a couple degrees and went to watch the pressure gauge - it did not move at all. It was at 0 the whole time. I remember checking it a week or two ago, and remember the needle being around 1 psi (I think). Is it normal for it to be at 0, though?

One thing I did notice is that the sight glass surge is massive -- in the time I spent watching for the pressure while the boiler was on, the water bounced around a ton, almost hitting the bottom of the sight glass and almost hitting the top, numerous times. The water is brown, though when I flush the system for dirty water, it's not that bad, and when the boiler is off for a bit, the sight glass has green water in it (green clean was applied to the boiler during annual maintenance). We also have an automatic water feeder (cannot be shut off) which, since the radiator repairs, has been cycling on dramatically more than it was before. It has been cold, so I'm not sure if that's normal, but just by example, the digital read was 154 on 1/9 and is157 today. The plumber who did the rad repair claims if water were leaking out of somewhere, we'd see it, and says that the repair has nothing to do with this or the hissing, which he says is normal......

I'm a little wary of taking the pressuretrol off the pigtail because I have never done that before. FWIW, we did have the annual boiler servicing a couple months ago; I'm assuming they did this... then again they also broke a washer in (and jammed) the valve I use to flush the dirty water out, and didn't tell me, so who knows.

I see two main vents on the pipes in the basement. Both are Gorton #1 V. One hisses like the radiators do now, the other makes no noise. The one that makes no noise is actually partially above the finished ceiling in the basement - there's a hole cut out for it. Also, I have been told before by a plumber that the boiler we have is too big for our house...

Another fun piece of info -- a friend had come by in the fall and offered to "flush the system" for us; I thought he had an idea what he was doing, but turns out he flooded the system. There was water shooting out from many of our vents on the first floor (none on the 2nd fl) and both mains in the basement. Not sure if this is related. The vents didn't hiss after that, they only started hissing like this post-radiator repair a few weeks ago, but I've been wondering whether there's some connection.

Sorry for the novel, and thanks for any and all help!

Fred · January 2017

First off, if the water is bouncing that much, and some chemical was added to the boiler, drain the boiler and refill it completely to get that chemical out of there. Many chemicals are not meant to stay in the boiler and others, while they can stay in the boiler, if too much is used they will cause foaming and very unstable water. You have to be able to turn the water feeder off. If you can't, find a shut-off valve somewhere on that line that feeds that water feeder and shut it off there or shut the main water to the house off while you are draining the boiler. When all is said and done, you need to have a handy shut-off somewhere near the boiler so that if/when the feeder ever sticks open, and they do, you know where to shut the water to it off. Otherwise you will find yourself with a flooded house, much like your friend did, or worse.
Given your friend flooded the boiler/mains and some first floor rads, once you drain and refill the boiler, you will need to either clean or replace and main or radiator vents that don't properly close when steam hits them. They probably got some crud washed up into them when they flooded.
One final note, you need much better venting on your mains than one Gorton #1 can provide.

Jamie Hall · January 2017

Where are you located? I'm thinking that it may be time for you to find a really good steam man to come and look at this situation.

At a guess -- and it is really only a guess -- you have more than one problem.

I would take the pressuretrol -- and pressure gauge -- off the pigtail (do not try to turn the body of either -- there should be a hex below the body; use a wrench on that), and take the pigtail off and make sure it is clear. Also check that the openings to the pressuretrol and the pressure gauge are clear (but no sharps or wire, please -- toothpicks if you need to get anything out!). Reinstall (teflon tape works well on the threads). Then check the pressuretrol settings. If you send us a picture we can suggest how to set it. Then run the boiler. If the pressure gauge is the usual 0 to 30 psi gauge, it shouldn't show much if any movement before the pressuretrol turns off the boiler.

I would also be very much inclined to find a day when the weather is warm and going to stay that way, and drain the boiler right down and refill it with clean water to half way up the sight glass. Some (or all!) of the "bounce" in the sight glass may be due to the cleaning compound which was put in; boilers are finicky about that, and most work best with nothing but water in there (although some folks do like a product called SteamMaster -- used very sparingly).

The boiler may very well be too big -- they often are -- but until we get it to behave there's no point in worrying about that.

As I said at the top, though, if you can find a really good steam man (try Find a Contractor on this web site) that may well be your best bet.

heatinghelp819 · January 2017

Thanks. I'm in NJ. Any recs? A couple people I had seen recommended on here in years past are no longer working, so I'd love recommendations for GREAT steam guys.

The main water shutoff to the house is right by the boiler, which I know how to get to in case of emergency.

As for the previous flooding of the system, why would the vents only be hissing now, and not soon after the system had been flooded? It's been a couple months...

heatinghelp819 · January 2017

Also what type of vents for the mains do you recommend, assuming I can have two?

KC_Jones · January 2017

@Dave0176 @EzzyT both work in NJ and both are fantastic.

Fred · January 2017

@EzzyT and @Dave0176 both are in that area and are excellent steam Pros. Until the outside temps get cold, rad vents may never close until it gets cold enough for the rads to heat all the way across. The vents may not have needed to try to close until recently. M<any of us are huge fans of the Barnes and Jones Bigmouth vents or the Barnes and Jones Vari-Vents for main venting. They are both available through he store here on Heating Help but we need to know how long and what diameter each main is and we can tell you how many you may need. They are built to last a lifetime and are less expensive than the Gorton #2 with double the venting capacity.

EzzyT · January 2017

@heatinghelp819 send me a private message

heatinghelp819 · January 2017

Some more info on my system. I popped into the boiler room this morning. The sight glass water level was very low, the LWCO light was on. Pressure gauge was at 4 PSI. (I'm not sure if the radiators were hissing at the same time, as the part of the house I was in before this doesn't have a rad). Soon, the water feeder kicked on and filled the boiler, pushing the meter up to 158 (from 157), and the water in the sight glass went up, and LWCO light went off, as expected.

My thought is that perhaps the crazy surge going on triggers the LWCO and auto water feeder, maybe when not necessary? And then the water feeder kicks on, adding water that may end up actually overfilling when the surge is on the upswing, leading to the hissing rad vents? Could this be? I was told that the green clean added to the boiler would HELP the surge, as we had a dirty boiler and the sludge or whatever is in the boiler was causing the surge, which the green clean would help with. I'm beginning to think this boiler just needs a good skim.

I also noticed that a narrow copper pipe coming off of the water feeder (not directly, but off a branch- pic attached), is very slowly dripping water. The cement under it is wet. I'm not sure how long this has been going on; it's the first time I've looked back there. This pipe doesn't appear to be connected tot he boiler though. Would this lead to the water feeder meter going up?

heatinghelp819 · January 2017

Abracadabra · January 2017

4 psi is too high. If you have a 0-30 psi gauge install a 0-3 psi gauge and adjust the pressuretrol down to cut-in of .5 and a differential (inside white knob) to 1psi

heatinghelp819 · January 2017

Pressuretrol is as low as it can be. Pic attached. Why would the psi be going so high?

Abracadabra · January 2017

What's the inside dial set to? The setting shown on the outside is the cut-in. The cutout is the cutin displayed plus the differential which is inside? Is the boiler firing when you took that pic?
0-30 psi gauge is worthless to use to determine boiler pressure. Get a 0-3 psi gauge on there.

BobC · January 2017

The white dial under the pressuretrol dial should be set to one. It's also possible the brass pigtail under the pressuretrol is blocked so the boiler has lost it's pressure control.

Bob

Fred · January 2017

The boiler needs to be drained and fresh water put in it AND it must be skimmed. A lot of people think those cleaners will remove (breakdown) te oils in a boiler. They don't work. The oils on the surface of the water make it difficult for the steam bubbles to break the surface of the water and that is one of the causes for very unstable water. Also, if the Pressuretrol is set to its minimum setting, either the pigtail is clogged and the Pressuretrol can't see the boiler pressure or the Pressuretrol needs to be re-calibrated. Drain and skim it first. The source of that leak needs to be found and fixed as well. As has been said, if you don't have a 0-3 PSI gauge on the boiler, put one on so you can see the actual pressure. If you are seeing 4 PSI on a 0-30 gauge, there is a good possibility the actual pressure is even higher that that. Those 0-30 gauges are not accurate at all.

heatinghelp819 · January 2017

Is the draining and skimming something I can (should) do now, in the middle of winter?

As for the leak, you mean the one on the pipe I took a picture of, or do you think there is a leak elsewhere given the water feeder readings?

Fred · January 2017

Draining refilling and skimming the boiler is a simple process. The skimming part takes hours to do it properly so you may want to wait for a mild day. If you are somewhat handy this should not be a problem. I am referring to the leak in the picture. Even if it is not feeding the boiler, it should be fixed. Is it leaking from the pipe that drops off of the Boiler Pressure Relief valve, on the side of the boiler? If so, that Valve needs to be replaced.

heatinghelp819 · January 2017

Thanks Fred. I think I am going to leave the skimming to a pro. And I guess wait for a milder day. (I wasn't sure how urgent this all is and whether my boiler will explode or something). Should I also have them replace the main vents, as discussed above?

Any thoughts on the water feeder meter and why it's increasing so much? Think it's related to the surging?

Fred · January 2017

@heatinghelp819 said: Any thoughts on the water feeder meter and why it's increasing so much? Think it's related to the surging?
If the added water is from the surging, the boiler should be over-filled when the heating cycle is over and the condensate has returned to the boiler. Watch the sight glass 10 or 15 minutes after the boiler shuts down. If the water level is high, yes, it's the surging. If the water level is normal, there is a leak somewhere and even more reason to investigate the source of that small puddle near the boiler.

heatinghelp819 · January 2017

Boilers been off for a bit. Water is at the normal level, and green (since it filled with "fresh" water this morning). I don't see any leaks anywhere except for the puddle that was behind the boiler, which had quickly dried up earlier today. I'm wondering if the puddle is from some water escaping when the water feeder is filling the boiler.

Maybe we are losing some water in the air vents that are hissing (perhaps it's steam and not air?) but not sure that makes up the amount the feeder meter is reading.

Fred · January 2017

There will definitely be some water lose (steam) if the vents are not closing and hissing while the boiler is running. I say do the drain and skim and see if the water usage drops.

heatinghelp819 · January 2017

Ok.

This is what the inside of the pressuretrol looks like. No idea where the marker for the dial is.

KC_Jones · January 2017

It's set to 2, turn the wheel until the 1 is facing forward where that 2 is now.

heatinghelp819 · January 2017

Thank you! If I saw the pressure gauge at 4 PSI when the pressuretrol settings are .5 and 2, is the pressuretrol working properly?

KC_Jones · January 2017

The 0-30 gauges are about as useful as a screen door on a submarine. Need to verify the cleanliness of the pigtail and install a good low pressure gauge. IF the pigtail is clean the gauge can't really be trusted. That boiler is basically operating within the gauge error rate so it won't tell the whole story.

Fred · January 2017

use this gauge: http://www.valworx.com/product/low-pressure-gauge-25-0-3-psi Just add a Tee to the pigtail the Pressuretrol is mounted on, a nipple and an elbow and mount the 0-3 PSI Gauge.
I can post the instructions for re-calibrating the Pressuretrol if, after cleaning the pigtail, you find the Pressuretrol is not accurate.

New England SteamWorks · January 2017

heatinghelp819 · January 2017

So a pro recommended here came out to look at our system. He confirmed that the boiler is too big for the house. He said that unless we get a smaller boiler, or fix some of the piping (current piping too small), or do stage firing, the hissing won't really stop. He wasn't sure why the water feeder meter is climbing like it is, as he didn't think there was a leak (his hypothesis was that the rad vents were letting out steam, but I'm not convinced yet for many reasons). I'm not sure how else to figure out where this water is going. He did say the boiler needed a good clean/skim, and said he could also replace the main vents with the Barnes and Jones varivents.

Two questions:

1. What are the pros and cons of staged firing? He said it's mainly used in commercial systems but that it could be almost as good as getting a smaller, properly sized boiler. I was reading about how it can cause chimney condensation though. Can someone explain in laymans terms whether this is an issue? Our chimney is partially exposed in the attic and already has efflorescence. Not sure how long that's been going on.

2. True that we will just have to live with hissing from our rad vents if we only give the boiler a good clean and upgrade the main vents (without doing the staged firing, or changing out the piping and boiler)?

Many thanks.

nicholas bonham-carter · January 2017

My suggestion would be after a thorough skimming, to first increase the main venting, and install a vaporstat, (whose low-pressure operation is verified by a good low-pressure gauge). This could be done immediately.
If there is short-cycling after that, then rectify the piping in the summer, along with some downfiring.--NBC

BobC · January 2017

Two stage operation can let the boiler run at a high firing level until it begins to build a little pressure, then it steps down to a lower level to finish the heating cycle. Care has to be taken that the flue temperature does not ho down too far, that can corrode the chimney. Combustion also has to be checked to make sure the boiler is operating safely. Is this chimney exposed on 3 sides as it goes up the side of the house?

Converting the boiler is not cheap so you would have to determine if it's worth it to you. With an oversized boiler it's going to cycle but that does not mean you have to live with noisy vents. If the cutoff pressure is 1.5PSI or less the vents should not hiss loudly.

Bob

KC_Jones · January 2017

How oversized is it and what does the piping look like?

The positive of stage firing or down firing in your application is avoiding the expense of changing out the entire boiler.

heatinghelp819 · January 2017

NBC - yes he had actually mentioned vapor stat installation and low pressure gauge install as part of installing the staged firing mechanism. How does a vapor stat help my issue? Would installation of the vaporstat CAUSE the short cycling, or are you saying if it's still short cycling due to the large size of the boiler? (Trying to assess risk of installing vaporstat).

BobC - yes chimney exposed outside on 3 sides. I'm wondering now if the efflorescence we see inside is because there's a leak in the boiler and steam is going up the chimney (which would explain water feeder readings). How much steam should I be seeing coming out of the chimney when the boiler runs properly vs if there's a leak? I still don't know why this would happen suddenly after our leaky rad repair.. Or maybe it's just been gradually getting worse. How does one check the flue temp and combustion? Is this standard when installing the staged firing? Would staged firing achieve the same result as fixing the piping? Should we do that instead?

Based on the recommendation here, I changed the inside dial of pressuretrol from 2 to 1, and the outside is at .5 (lowest setting). Hissing has gotten a little better but still happens everytime boiler runs. We never had this hissing issue last year.

I am leaning towards doing the clean/skim and main vent replacement now and seeing if that helps the hissing and water loss. If not, then moving forward with two stage firing or fixing the piping.

Abracadabra · January 2017

check your main vents. they are probably inadequate or have failed and all your mains are venting thru your radiator vents now causing more "hissing"

the vaporstat would be installed to control to hi-lo fire of the boiler.

Fred · January 2017

How much over-sized is the boiler? What is the total EDR of your radiators and what is the Sq. Ft. of Steam rating on the boiler plate? I am almost certain that if you drain that boiler and get that chemical out of it and then do a very slow skim AND make sure the Pigtail that the Pressuretrol is mounted on, is not clogged, that you can eliminate the hissing vents. Putting good venting on the Mains essential as well but if you didn't have the hissing last year, the chemical/need for a skim and possible clogged pigtail are the likely culprits.
Two stage firing can be done and is an effective way to reduce steam production to better match your attached radiation but you really need to make sure the boiler is not leaking and be comfortable that it has several years of life left in it before you invest in two stage firing. Even being over-sized, if the pressure is properly managed to around 1.5 PSI, the vents should not hiss. Also, make sure, after you do the boiler drain, skim, main venting and pigtail cleaning, that the vents are actually hissing on pressure and that the sound you hear is not the vents sucking air back into the system AFTER the boiler has shut down from a heating cycle.
Just think back to what changed from last year! If I heard you right, it's the chemical that was added to the boiler and possibly a clogged pigtail, which can happen at any time.

heatinghelp819 · January 2017

Yea the possible leak thing is really throwing me for a loop. Definitely will have to figure that out before investing more in this boiler with a staged firing install.

The things that have changed since last year are addition of the chemical and the worsening and this repair of the leaky radiators, and whatever other additional gradual decline of anything else that might have been only slightly wrong before, which is indeterminable at this point.

Vents are hissing both on firing and after shut down (vacuum); my concern is the former.

By the way, I checked the pressure the other day and it was 1.5-2 PSI (down from 4), so turning down the pressuretrol helped but the rads are still hissing (a little better but still happening).

Thanks all for the help. Doing the clean on Saturday and will update.

Fred · January 2017

I think the clean out of the chemical and the skimming will resolve the hissing issue. But as much venting as needed on the end of the mains to get that air out of the system and not put that burden on the small radiator vents. Keep us posted after the clean-out/skim.

Fred · January 2017

BTW, Also know that any significant leak in the system, especially at or near the boiler, other than a wet return, would prevent the system from building pressure, so the most likely cause for water loss is the vents or leaky valves or a faulty water feeder that either registers more water than actual or that does not open the internal feed valve on a call for water (may be intermitent)

Air vents hiss whenever boiler is working

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