Cast Iron Radiator Air Vent Leaking

3 years ago

I have on an old style (early 1900's) cast iron radiator. The air vent valve has a crack in it and it's leaking water. I have two questions...

1--I was told I would need to replace the valve with a new 1/8" valve. Any tips on draining my system/isolating a radiator? I could really use a good tutorial on this.

2--Instead of replacing the valve, I'm wondering if I can put some type of a patch on the leaking valve. I tried JB Weld with no luck. Does anyone have a product that would work for this type of leak?

Featured Answer

mike_home

3 years ago

The video above shows how the replace a vent on a steam radiator. In this case the air bleeder valve needs to be replaced on a hot water system radiator. One cannot be substituted for the other.

Did you try JB Water Weld? The manufacturer claims it can withstand 4370 PSI and 300F degrees. I have never done this so I can't say if it will work.

To drain the radiator you will need to shut off the boiler and the water feed. Then you have to drain water out of the system. There should be a drainage valve near the bottom of the boiler. You will likely have to connect a garden hose to do this. After the valve is replaced, you will need to fill the boiler with water and then bleed the trapped air out of every radiator in the house. You should be able to find a YouTube video on how to do it. I think the hardest part is removing the old valve without breaking the threads.

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Comments (10)

Stax
3 years ago
TOCL&H thanked Stax
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TOCL&H
Original Author
3 years ago
Thank you for the suggestion. I haven't tried the JB Water Weld--I didn't know that they had that product.

I am definitely going to try that first, but if it does not work, do you know if it's possible to avoid draining the entire system? I thought I could maybe just shut off this one radiator. There is some type of valve that I've shown in the last photo, but I could be mistaking this for a shut off valve.
TOCL&H
Original Author
3 years ago
I thought I'd post an update...I tried the Water Weld, but didn't have any success. I ended up calling in a plumber and he was able to replace the old valve--he did it "live" to avoid draining the boiler system. It was a 15 minute job--glad to be done!
elunia
3 years ago
Excellent ending!
TOCL&H thanked elunia
mike_home
3 years ago
How much water came out when the valve was removed? Did the plumber add water to the boiler and bleed the radiator after the valve was changed?
sktn77a
3 years ago
Sometimes, you just gotta pay "the man"!
wishiwereintheup
3 years ago
Plumbers know what they are doing!!

BTW, that's a beautiful radiator. Exceptional detail on it.
TOCL&H thanked wishiwereintheup
TOCL&H
Original Author
3 years ago
mike_home --Sorry for the slow reply! The water that came out of the valve was minimal--about a cup. He had the new valve already to go. Then after he removed the old valve, he "thumbed" the valve quickly to stop the water flow, then popped the new one right in. He did not add water to the boiler or bleed the radiator after the valve was changed.
mike_home
3 years ago
There is likely a small amount of air trapped at the top of the radiator. If the radiator gets as hot as it did in the past, then you should be fine.