OT - leaky air vent on hydronic radiator

[Bob Engelhardt]

I have an air vent that is leaking water:



The leak is "under" the adjust knob - most likely the gland sealing the shaft. Of course the knob is frozen or I'd just close it. If I force it I'd likely make things worse - BTDT.

There are no isolation valves for the zone (what were they thinking?), so I'd like to put a band aid on it until the heating season is over. I've thought of a couple of things, but I'd like to hear if they have been tried and failed before I go through the try and fail myself.

My first thought is to use that self-fusing (self vulcanizing) tape - it's non-adhesive and sticks/seals to itself when it's stretched during application. It's made to seal leaky pipes, but this is kinda extreme. A hose clamp around the tape? There's pressure in the system, but not that much - 15psi?

Another thought is to fashion a dam around the vent and fill it with hydraulic cement. The stuff works under water & expands as it cures. But not against pressure?

Epoxy is not going to adhere to wet & pressure, is it?

Anybody had this problem & found a work around?

Of course I could just turn down the thermostat on that zone, let it cool off and work fast to replace the valve "live" (under pressure). Sure as shyt the vent would break & I'd be up to my neck in it.

[Cuttings]

There is an underwater epoxy that is used for emergency repairs to holes in a boat. It should set up and bond there providing the water pressure doesn't push it away before it sets up. Some of those air bleeders used to have a piece of cork in them which would dry out if there was air under them and shrink, then once the air was gone and it got wet again it would swell and shut it off.

[wmgeorge]

Put a pan under it, and wait til spring. You could get lucky removing it, BUT if it strips or breaks your SOL. Have the exact replacement when you do and way to re-tap the threads if needed.

[john b]

JB weld fiber weld.. I have used a similar product. Once applied massage it firmly until it cures. The foam that is activated when dipped in water is like. Gorilla glue and will expand.

[Bob Engelhardt]

Put a pan under it, and wait til spring. [snip].

That was my first thought, before I could actually see the problem. It goes straight down through the floor & it inaccessible below. Worse, the pipe touches the floor & the water is wicking between the sub floor & finished floor

[Bob Engelhardt]

JB weld fiber weld.. I have used a similar product. Once applied massage it firmly until it cures. The foam that is activated when dipped in water is like. Gorilla glue and will expand.

Thanks! Looks good: "Once the product is dipped in water for 5-7 seconds, you will have between 5-10 minutes to work with the product and then it will fully cure in 15 minutes! "

Delivered tomorrow: https://www.amazon.com/dp/B08B3HBQF9/

[wmgeorge]

A epoxy that will hold pressure under heat?? I see it holds water pressure 60-70 at normal household nothing about heat.

[Bob Engelhardt]

A epoxy that will hold pressure under heat?? I see it holds water pressure 60-70 at normal household nothing about heat.

We'll see.

[john b]

when applying clean with abrasive NOT wire brush.have a sqirt bottle with water to apply while wrapping it works better than dipping. When mixing,kneeding, epoxy mix until it start to feel warm then apply vigorusly. after tape has been applied massage the tape thoroughly.

[deltap]

Turn off the power and let system cool enough that you won't burn yourself when working on it. Close off water feed to system and drain at boiler to zero psig. Get the new part ready to install with tape or pipe dope. Unscrew the old part and catch the new one on the fly. You can put a towel around the pipe to catch the small amount of water that will escape. Vacuum in system will prevent only a little water to escape. Not a fan of auto vents. Use a manual vent. Once the air is first driven off there is no further need for venting if new makeup water is not added to the system.

[Bob Engelhardt]

Turn off the power and let system cool enough that you won't burn yourself when working on it. Close off water feed to system and drain at boiler to zero psig.
[snip].

That's exactly what I'm trying to avoid with the "band aid". I've worked on enough old plumbing to know that what you see is often not all that you get. In this case that vent may have been there 60 years and at least 35. I'm not going to screw with it until it doesn't matter how long it takes. Thanks anyhow.

[Bob Engelhardt]

[snip]
My first thought is to use that self-fusing tape - ... A hose clamp around the tape?
[snip]

In the meanwhile I tried the tape - it didn't work. I think that the constant water presence inhibited the fusing. The clamp didn't help.

[old mart]

I have never seen an auto vent built into a valve before, not on the eastern side of the pond. I would be inclined to lever off the plastic cap for a look, maybe there is a gland that can have some ptfe tape put in it.
You can buy a leak inhibitor, try a plumbing/ heating shop.

[Bob Engelhardt]

when applying clean with abrasive NOT wire brush.have a sqirt bottle with water to apply while wrapping it works better than dipping. When mixing,kneeding, epoxy mix until it start to feel warm then apply vigorusly. after tape has been applied massage the tape thoroughly.

Thanks! Yours sounds like the voice of experience & that's the very best kind.

[Bob Engelhardt]

Sometimes it's better not to overthink things: