Loud hissing from nearly all radiators during this cold spell

My pressuretrol originally with the same settings you are at (0.5 main, 1 diff) let my pressure rise to just over 3psi. I was able to tweak it to shutoff at 1.5psi but you would need the new gage to attempt this adjustment. Some pressuetrols simply may not adjust down far enough before not letting the the boiler cut back in.

@Day_Tripper You and I could be in the same boat as far as maybe having Hartford Loop problems where it is too high. See Hartford Loop thread for my mickey mouse setup. I would prioritize checking and fixing that. I am relatively OK keeping my water level about 1 in. higher than NWL but only when water is pristine clean and relatively low in TSS particulates. Your setup with the shared main and returns with Tees I'm sure makes your system more unpredictable as far as balancing steam and return of condensate. When you have a threaded Tee I don't know how it will be possible to have downward pitch leaving both legs unless you have pipes that were purposely (or happy accident) threaded crooked and you index them properly for pitch. Your Blue line may be substantially counter-flow as a result.

When I advised you to remove vent and plug it I didn't realize that this radiator had a hole in the bottom. You mentioned that the water was coming out of the vent so I focused on that.

Fixing it would be as much work as replacing the supply shutoff valve because you would have to remove the radiator and the valve and cap the pipe. You will need a new radiator and a new valve. Can you put a large tray underneath the entire radiator? You'd have to disconnect the radiator, put the tray underneath and reconnect it. Also a PIA. I don't know if it is feasible to repair a radiator with high heat JB Weld epoxy putty or Xpando or the like, or if you did, how long it might last.

@Goodhap I second @Captain Who on using the J-B Weld WaterEpoxy where there is any water leaking. Just unload the entire stick anywhere you see some water dripping. You will have to replace the inlet valve at some point at a minimum. If you want to abandon the radiator you can just have a plumber cap the run. The J-B Weld will stop the water leaking temporarily. I've used it on my pressure vacuum breaker for my lawn irrigation system that had a leak. I just mixed it up and mashed a ton in the crack and it works fine now. I'd try to do this today.

I've never used this stuff but I bookmarked it a while ago:

Iron Paste

 withstands temperatures up to 400° F and also withstands pressure up to 60 lbs. on water, oil, steam or gas lines.

https://www.blackswanmfg.com/Category-04/Iron-Paste.HTML

I just had the same issue. Turns out my pigtail was clogged. I took it off and cleaned it and my system immediately went to near silence. Try removing and cleaning out the pigtail. It took me about 30 minutes to do.

Definitely do your sizing calculations just to know what you are working with and how to tailor expectations. Two cups of coffee in the morning and a cheat sheet like the one attached and you can do it yourself, no need to pay anyone. Just total up all the sqft calculations for each radiator and compare it to the rated sqft on the boiler. Don't worry about btu's.

Great video. I did jump advance through parts of it for time, but here is what I see:

• overall operation is fine, I see no sign of carryover/surging (as evidenced by your relatively steady waterline
• Your Gorton #1 is definitely busted. Replace it. I like Maid O Mist because they are cheaper and basically the same, but they both fail (as evidenced by your video). Interestingly, people here crap on MoM all the time because their seams aren't soldered like Gorton is, and here is a soldered Gorton that doesn't even look old clearly split. I shop at supplyhouse.com
• Your Gorton #2 seems to also be leaking at .5psi and it should probably be replaced. You could take it down and try to shake it or smack it in hopes of dislodging something inside that is preventing it closing but I have not had success with this.
• These vents leaking is not causing you any trouble upstairs. But it causes the loss of water from your system and that is something you should address to prevent excess corrosion of your boiler.

PS: Note that everything leaks more with higher pressure. You might consider avoiding thermostat setbacks so that your pressure is kept to a minimum (I assume your system sees lower pressure during normal operation and only goes higher when you bump up the thermostat as you did for this video)

For comparison, I have a low pressure switch tied to a timer relay that interrupts all my calls for heat when my pressure gets to about 1/4 psi. This makes it take a long time to recover from a temperature setback of course, but the result is very low pressure and wasted fuel (I consider fuel that goes into pressurizing a steam system to be wasted, even though it somewhat isn't)

If my system were running at 2psi I'd probably have leaks all over the place LOL

To answer your notes above:

3. Your #1 vent for sure is hissing because steam is escaping through that leak in the seam
4. There are two types of steam vent: Those that have failed, and those that haven't failed yet

if you keep your temp at 71 how high does your pressure get during the call for heat?

MoM and Gorton both fail. They all fail. You might see if supply house will take that split one back at least

if it works, it works!

Call supplyhouse and see what they say but maybe come at them a bit lighter than above lol they are good people

You may find on a normal call for heat that you see almost no pressure

Why did his vent(s) fail in only 6 months?

My Gorton's are all going on 13 years now and I haven't had one fail out of 16. That can't just be luck?

@ChrisJ your guess is as good as mine

@Captain Who I'll keep that in mind. I'm just going to keep the #2 in place and pray for the best because it was a nightmare to get that #2 in and I don't want to take ir out during the heating season. Hah I know I felt bad about the take over but I do hope my situation can help @Goodhap since we both have similar problems.

I think it can be luck. I and many others had Gorton #1's arrive DOA

Just unscrew that street elbow maybe 45 deg, then put one holdback wrench on the street elbow and the other wrench (use a large adjustable) on the Gorton and unscrew it. Then reverse the procedure with the new one, or design an antler tree for 3 #1's.

@Goodhap my water is so clean because I'm using make up water way way way too often. With my leaky vent, a lot of water is lost. I do flush the boiler down a few times during the season.

Concerning the pressuretrol, yes. You have a cut in and a differential. You can see in my earlier post I took the front cover off my pressuretrol (which is the same as yours) and you can see my cut in on left is all the way down (via the screw on the top left) and differential wheel is at 1. So in practice the boiler should cut in at 0.5PSI and cut out at 1.5PSI (0.5 + 1 diff). If you cleaned out your pigtail and your differential is set correctly, your system should only operate under 1.5PSI. You can see in my video that my pressuretrol is a bit out of calibration because it cuts in a 0.8 and out at 1.8 (0.8 + 1 diff).

Concerning the continued hissing, I'd defer to some of the vets on why this continues. They might be old and clogged at the air hole.

@Goodhap unless you completely blow down your system there is still a fair amount of mud at the bottom of your boiler and in the mud leg of the wet return (if you have that type of system). If your system is down while the plumber replaces the inlet valves you could try and flush your boiler. It's not too complicated.

Once you get your inlet valves replaced and your leaky radiator closed off your system should be good.

Having multiple vents fail at the 6 month mark tells me something is very wrong, call supply house and see what they can do. If they can't help a call to Gorton is in order.

My system runs at 12oz but back when it was at 2PSI the vents made only a very light hissing noise.

Hissing vents makes me think your pressure mat be higher than you think. Maybe the pigtail is partially clogged? Your pressure gauge might be lying, the 30# gauge is pretty useless - think about adding a 0-3 gauge so you can see what is really going on. Pressure sb kept under 2PSI.

Bob