Can't Get Whistling / Extensive Air Relief Sound Under Control

IanMac227

Hello! We bought a house with a one-pipe steam system feeding 10 different steam radiators throughout our house. Initially, all of the radiators were setup with "C" or "D" vent valves (Maid-O-Mist and Gortons). There has been significant noise from the air vents on the radiators and they were all poorly balanced. I have most of them balanced a little better, changing certain vents to 4s, 5s, and 6s, like the diagrams show. Using a thermal gun they are all much closer to heating up at the same time. But the vents still make a whistling sounds as they heat up, even with brand new vents. It isn't consistent, they all whistle and then get quieter and then back to whistling (not very high pitched, more like someone learning how to whistle and struggling), like the pressure pushing out the air is varying. Is this an issue with the boiler or something else related to the venting setup?

The main has two vents, both Gorton #1. I have new ones but they are in difficult places to change so I haven't gotten to them. The mains heat up pretty quickly and I do hear some air coming out of the main vents. The mains aren't insulated, I am working on ordering insulation now. All of the radiators are angled properly as well, no water hammering. The thermal gun shows about 210 deg F on the main right off the boiler. Boiler was serviced a month ago, but it was really just a cleaning.

Jamie Hall

Get the new main vents on there. That may make a useful difference — though it may not end the problem. Also get the mains insulated, and check very carefully along their whole length for any sags or even relatively flat stretches. The variation in sound makes me wonder if there aren't stretches where condensate tends to collect while the system is heating up. Not stopping the flow of steam, but momentarily slowing it down.

Beyond that also check what pressure the boiler may be set to, although that is not likely to be a problem near the beginning of a heating cycle.

ethicalpaul

Insulating the mains is fine idea, it helps put the heat where you want it and keep it from where you don't, assuming you don't want your basement warmed.

But it will not have a positive effect on your whistling, and may actually make it worse. Here me out @clammy and other friends 😅

A. If the mains are COLD when the call for heat begins, a lot of steam will go toward warming the pipes (this is true regardless of insulation, I hope we agree). This makes the steam push a lot "slower" along the main because steam is condensing as it moves slowly along the main. This will make an undersized main vent perform just fine because the volume of air that has to be vented is spread out over a much longer time.

B. If the mains are HOT when the call for heat begins, much less steam will go toward warming the pipes because they are already warm. The steam will move much faster along the main, and the job of the main vents will be much larger because the same volume of air that is in the main is going to be pushed in a shorter time period. This will in turn put more pressure on the radiator vents because the main vent will be overwhelmed, increasing the amount of air pushed through the radiator vents, and increasing hissing.

And by insulating the mains, there will be many more times when the B situation occurs.

So my advice would be don't bother with insulation until after get your main venting where it should be and/or get the hissing figured out. There are other threads that explain how to time your main to see when you have enough main venting, and I recommend that procedure rather than just trying to do the math. It eliminates all unknown variables by letting the actual behavior of your main dictate your venting.

There are other variables that could be affecting your hissing as @Jamie Hall mentioned, including the question of "is your boiler oversized?".

IanMac227

Thanks for the advice. I will try and change the two main vents and see if there is any difference. I don't think there are are sagging or low spots on the mains but I can double check that. I'll also look into timing the mains and confirm whether the main venting is an issue.

What pressure should I be looking for off the boiler? Like mentioned, I do hear it pretty quickly as the lines fill with steam. The boiler is a Weil-McLain SGO-4 (144,000 Btu/hr capacity).

ethicalpaul

If you have a low-pressure scale gauge (like 0-3psi) you would hope to see just a slight movement well under 1/4 psi.

If you have a factory-installed 0-30 psi gauge you would hope to never see it move. But they are almost always broken anyway and never move, so that is a false sense of security there. If it is working, you might see it slowly rise up to 2-3psi once all your radiators are full of steam, to the point where your pressuretrol shuts off the boiler on pressure.

If you see it go up quickly to 2psi or higher then your boiler is almost certainly oversized.

IanMac227

Okay thanks. I have a 0 - 30 psi gauge and haven't seen it move yet. Wasn't sure if it was working or not.

bburd

@IanMac227 can you post pictures of your pressuretrol, with the cover on and off? We need to see the settings. Also, has the pigtail between the pressuretrol and the boiler been cleaned? Sometimes they clog up and prevent the pressuretrol from sensing the steam pressure.

EdTheHeaterMan

https://forum.heatinghelp.com/discussion/comment/1821123#Comment_1821123

That's a good thing. Your home should be able to heat at less than 1 PSI. If that gauge is not moving, then you are operating at about 1/2 PSI or less. In order to diagnose your whistling issue, you may want to invest in a low pressure gauge. You need to leave the 0-30 gauge in place by code. This would be in addition to that gauge. https://www.supplyhouse.com/Winters-Instruments-PLP302-2-1-2-PLP-Steel-Low-Pressure-Gauge-1-4-Bottom-NPT-w-Brass-Internals-0-55WC. This gauge measures up to 2 PSI in ounces per square inch.

IanMac227

Here is a pic of the pressuretrol. Looks like it's set right around 1 psi. I pulled the gauge off and it does seem like there is gunk throughout the pigtail. Doesn't look completely plugged but obviously I can't see the whole thing.

Also thanks for the link on the gauge. I can certainly look to add it.

bburd

That white wheel inside the pressuretrol should be set to "1". Pipe cleaners work well for cleaning out the pigtail; you should also be sure that the holes it fits into on both ends are clear.

IanMac227

I did confirm that it is set to "1". For cleaning the pigtail, were you able to clean it with pipe cleaners without taking it off? Just wanted to avoid unwiring if I didn't have to.

Jamie Hall

I've had better luck cleaning things like pigtails using long heavy zip ties than pipe cleaners — but your mileage may vary. If you have access to compressed air, you may be able to blow them out.

However… I think you may have to unwire things just to get access to the pigtail to work on it. Take pictures…

IanMac227

Hello all. Thanks for the advice on what to go after for the whistling / varying vent noise issue I've been having. Just to update, I did change both main vents. One was fine but the other was plugged and not venting. I also removed and cleaned the pigtail. I am now getting .5 psi reading on a low pressure gauge so everything seems to be okay there. So far, neither thing has made much impact honestly.

One thing I did notice is the slope of the main pipes. Coming off the boiler, they slope up as they go away, before sloping back down after a 90 on each wall (I will attach some pics) and heading toward the return. Could there be some condensate flowing back that could be causing the steam variation?

I also wasn't sure if I should skim / or drain and replace water in case there are contaminates causing issues. The pigtail was certainly pretty plugged up, I'm not sure the last time it was skimmed.

The venting whistling / "whooshing" does happen pretty quickly after the boiler starts up, especially if its already warm. So I don't think its a high pressure issue.

IanMac227

Jamie Hall

If those sections that slope up away from the boiler don't have a drip to the wet returns, they're going to give problems — whatever else you do with them.

EdTheHeaterMan

What we call condensate is actually water. Water flows downhill. That is one of the three things you learn as a plumper on your first day. (the other two have to do with pay day and fingernails).

So you have a counter flow system for the first section of pipe until the elbows near the wall. That seems odd but it is what it is. That could have happened when the new boiler waws installed years ago. (That WM SGO is not original to your home). So the question about the whistling noise may go back to this: When did the whistling start? Always there since you moved in? Just started this year? Other? Answer to this query may help us locate the reason. I doubt that it is the counter-flow changed to parallel flow design causing the problem.

Sounds more like the air leaving the vents is moving very fast thru a orifice that is out of wack. You know like what happens when you blow into a whistle. It is that offset angle that makes the air flow past the opening and causes a sound to happen.

IanMac227

There are no drip returns in those section, just the equalizer pipe. There are three radiators that pull off the "up-sloped sections" before the 90 sloping down to the returns. I figure it had something to do with the boiler replacement being a different height / pipe setup than previous iterations.

We've only lived there a couple of months and its been there since we fired up the system. Its not constant, seems like there is variations in pressure suddenly pushing more air through the radiator, enough to whoosh or whistle. They pretty much all do it. The radiators all heat up fine, just an annoyance, mainly in the bedrooms when trying to sleep.

I have a 0 - 10 oz/in2 gauge I could also put on to see if there is a lot more variation than my current gauge is catching.

EdTheHeaterMan

This is unfortunate, but that boiler may have been installed incorrectly. I'll bet that noise started as soon as the boiler was installed. For a counter flow to work properly, the steam main's pitch must be 1" every 10 feet so the condensate flows back even though the steam is rushing the other direction. The pitch on a parallel main is 1" in 20 feet. because the water flows in the same direction as the steam. The fact that there are 3 radiators worth of condensation going down that main into the equalizer could be the reason that there is a pressure change in the system after the boiler. think of it like waves on the beach during a hurricane. They get bigger and crash against the coast line with more force and then retract back to the ocean until the next wave hits the beach. The problem with those waves is that the "AIR" (actually steam vapor) has a ceiling, the top of the pipe, so that wave of water may cut off the "AIR" that is flowing in the other direction. That "Air" in this hurricane is steam flow and the waves are the returning condensation water.

Not sure how this is causing the whistling at the radiators though. You may need to have a steam expert on site to look at the big picture. but this might be a fix that will help.

I can't guarantee that this fix will stop the noise but it will get the entire system bacl to being a parallel flow system.

IanMac227

Yeah that makes sense, thanks for the info. I can certainly look at making that change to get things corrected.

In the short term is there anything I can do to help the noise? Any vent product that can potentially help reduce or silence it? At least in the bedrooms.