Some rads hissing, some not

RImoparGuy

Hi everybody, my wife and I recently purchased a colonial built in 1929 with its original radiators and a Burnham boiler (approx 10 years old).  The boiler is in great working order.  The house has 3 radiators on the first floor and 4 on the second.  The 4 upstairs are all smaller ones in the bathroom and the 3 bedrooms.

The issue I am chasing is that 2 on the first floor and 1 on the second floor are hissing through the heat cycle until pressure falls off.  When I noticed this I immediately replaced the air vents on all 3 of the noisy units.  I bought Plumbers Edge adjustable units from Home Depot.  I have since also adjusted the pressure on. The pressureteol down to 1.5 psi, it was up around 4 originally.  I also replaced the air vents on the two mains.  One of them was clearly venting noticeably and the other was venting nothing, so I replaced them both with Gorton #1 3/4”-1/2” straight vents.  Lowering the pressure helped a little bit but my living room, sun room and master bed still sound like a pressure cooker when the cycle is active.  Before I throw any more parts at the problem, I would love to hear some opinions on where to look next.  The other 4 radiators function beautifully.  They vent a little air, then they’re quiet and give off plenty of heat.  Any help or guidance is definitely appreciated!

ethicalpaul

Home Depot vents in my experience have a 100% failure rate. I like Maid O Mist and Gorton, purchased from supplyhouse.com

It was correct of you to lower your pressuretrol. The lowest setting is where you want it.

It was good to install the Gorton #1 vents on your mains.

With your pressuretrol set as you describe, and the main vents, you shouldn't really be having noisy radiator vents.

RImoparGuy

Something else I’ve now found.  I went down to check both new Gorton vents.  The one on the left is still warm (hasn’t cycled in a couple of hours), the one on the right is cold.  Maybe a blockage forcing too much pressure into one main?

Waher

Tap on those Gorton No.1 vents and see if they rattle. If the cold one doesn't, it may be stuck shut.

The No.1 on the left should be on a pipe nipple (black steel/malleable iron or brass) with a coupling like the No.1 on the right. Use Blue Monster tape on the threads, three wraps clockwise. The taller the better to protect the air vent from potential damage. Any new piping/fittings, other than air vents, should be washed and thoroughly rinsed with a degreasing dish detergent like Dawn to remove any manufacturing oils that would otherwise negatively effect steam quality.

What's your boiler sound like when it steams? Any pinball machine like noises? Is the water in the sight glass gauge steady or jumpy? The air vents that make noise on your radiators, do they spit? You may have oil on the surface of the water inside the boiler which is creating wet steam. That would require skimming to fix. Or the radiators themselves may not have their shut off valves fully open or have a pitch problem causing condensate to build up in the radiators which then gets carried by the steam to the vents making them hiss. Put a spirit level on top of each radiator to check the pitch and make sure the shut off valves at the noisy radiators are fully open.

TonKa

Are you sure the hissing isn't coming from the packing nuts on the radiator valves?

ethicalpaul

That Gorton on the right, is it connected to a counter-flow drip? I can't quite tell from this angle and with the insulation.

Instead of checking the vents two hours after a heating cycle, check them during a heating cycle.

RImoparGuy

Waher- the valves both rattled before installation tonight.  Boiler is super quiet while running.  I’ll check the levels on the radiators tomorrow.

TonKa- the hissing is definitely coming from the air valves

Paul- What’s a counter-flow drip?

Side note, I drained from the bottom of each main tonight as well just to make sure they weren’t clogged with gunk.  I have clear water coming out everywhere now.  We have a few warm days ahead but the next time it kicks on I’ll watch a cycle myself.

dabrakeman

Could you send a picture of the boiler piping from another angle?

RImoparGuy

dabrakeman said:

Could you send a picture of the boiler piping from another angle?

neilc

we're trying to see your header, and how or if it connects to the main coming at us on the right,
one more picture please

RImoparGuy

neilc

so this "vent on the right" really isn't doing much there,
see how the steam is going right to it, and shutting it off ?

what you need is that vent, at the far end of that same main "coming at us on the right", and possibly on the main teeing off to the left, unless what they're doing is looping full around,
or do they drop to wet returns at their far ends ?
if they drop, then the vent(s) belong just before the drops,

what happens at those far ends ?

neilc

and , , ,
post an upclose of the Ptrol,
you can probably lower your setting more,
which could help with that hissing,
as @ethicalpaul said, lower is better.

dabrakeman

You have 2 mains coming off the header and that Gorton#1 closest to the boiler is doing next to nothing to vent a main.  Move it to either after the last takeoff from the main or back where that main returns near the boiler.

RImoparGuy

Current settings of my Ptrol.  When I first checked they were way higher.

RImoparGuy

I’m wondering if I should just try putting a half way decent air valve on one of the whistling rads to see if it does anything, but I also don’t want to just start throwing parts at it.

neilc

are the hissing rads on the main "coming at us on the right" ?

RImoparGuy

So while I’m getting crazy whistling from the two noisy units upstairs, the two Gorton units in the basement are both hot, but quiet, seemingly doing their jobs.

neilc

right, but are those noisy rads being fed from that same main in the basement that we think has the vent too close to the boiler, and you're venting the rest of the main up thru these rads ?

Jamie Hall

The pressuretrol setting is OK

dabrakeman

RImoparGuy said:

So while I’m getting crazy whistling from the two noisy units upstairs, the two Gorton units in the basement are both hot, but quiet, seemingly doing their jobs.

The one Gorton main vent closer to the boiler in your picture is not doing it's job because it is not venting the main.