Leaking air vent, rusty water

[Artm69]

On my 25 year old Burnham boiler, suddenly an air vent developed a leak. as seen in the pics, the water is quite rusty. How should I proceed with this repair? Replacing the vent should be straightforward but what about the rusty water? I fear that may be a bigger issue.

The boiler has never been drained for maintenance. The only issue was an expansion tank replaced twice over the years.

 

[Fitter30]

Has the boiler had a lot of makeup water added to it over the years? Make up water contains oxygen and that isn't good for a boiler system causing rust in the cast boiler sections and steel piping. The air vent just unscrews replace it. Drain and refill boiler and drain again. Add boiler treatment to the system then refill. Can add treatment by pulling the relief valve. With boiler is drained look to see if the boiler gauge (tridicator) goes to 0 and the temp looks close.

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[Artm69]

1. I'm sure plenty of added water has come in over the years. I thought nothing of it. Which boiler treatment is recommended?

2. Some more symptoms , weird:

3. Circulator on, heat on, outgoing pipe past exp tank gets hot, and is so for many feet.
4. Return pipe before circulator, and many feet before, is cold.
5. Turning off system, pipe before circulator gets hot.

6. Pressure is low at 5 when off. When hot, gets to 10. When I press valve to increase, nothing happens, I don't hear any water coming in.

This boiler is in basement, going up one level only and has only one circulator.

 

[Reach4]

If your auto fill valve does not leak, and if your boiler pressure relief valve is proper, and if you have a working well-sized thermal expansion tank, then adding water should not be needed.

Thermal expansion tank air precharge should be the same as your refill pressure, which is often around 12 psi.

 

[John Gayewski]

If I were you I would use the lower drain on the boiler and blow out the rust. Refill with some treatment.

 

[Artm69]

1. Yes, on lower drain to blow out.

2. What treatment to use?

3. Refill pressure: is 12 psi a standard rule irrespective of the height of water travel? I've been running 20 psi for units 2-3 floors up, form basement. This unit is only one floor up.

 

[John Gayewski]

1. Yes, on lower drain to blow out.

2. What treatment to use?

3. Refill pressure: is 12 psi a standard rule irrespective of the height of water travel? I've been running 20 psi for units 2-3 floors up, form basement. This unit is only one floor up.

Yes 12 to 15 psi cold. It'll rise a little as the system heats up. Any rust inhibitor

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[John Gayewski]

The rust could've just been from your air separator. When you let out from the lower drain see if there's rust. If there's only a tiny amount you might want to think about changing to a spirovent. They are better anyway.

 

[Fitter30]

Rectorseal 8 way boiler treatment quart.

 

[Artm69]

So, drainded boiler, fairly clear, changed air vent and autofill valve. All looks good. Autofill was clogged, thinking of rebuilding it as a spare. It's a basic 1156, worth it?