New Taco Hy Vent leaking

heatwanted

I had a Taco Hy Vent on my boiler start leaking heavily from its bleeder cap yesterday. I replaced it with a new Taco Hy Vent and the new one is also leaking from the cap when opened the slightest amount. I did some research and found that my Amtrol 30 expansion tank was 30 years old so I decided to swap that out today since some people have said that could be a factor with the leaky vent. After a can of PB Blaster (and an almost torn rotator cuff) I was able to get the old tank off and replace it.
Needless to say since I am making a post, the Taco Hy Vent is still leaking. I appreciate any advice/suggestions that may help me here. I had actually called my boiler service company but they blew me off with no availability till Monday to come out. With freezing temps forecast for this weekend I am trying to head that off. Thank you for any help!

Alan (California Radiant) Forbes

Automatic air vents can be finicky devices. There’s a valve that opens and closes to let air out. If the valve gets fouled with debris, it will leak and very often, dirt accumulates at the same high point where the vent is located and you probably got some of that caught in the new valve. 

I don’t know how an x-tank can affect an air vent. 

EBEBRATT-Ed

@heatwanted most boilers operate at 12-15 psi cold and may get to 20-24 when hot. Why not remove the vent and install a ball valve or petcock under the vent . They can get dirt in them or if they are venting a lot they will spit water,

What pressure is the boiler running at? you could also have a bad gauge on the boiler fooling you. You can put a temp gauge on the boiler drain to check,

You also should check the air pressure from the expansion tank air side before you install it. It has to be off the system or isolated and drained to check the air pressure.......no water pressure acting on the bladder. Fill valve and expansion tank should be set to the same pressure 12-15 psi.

hot_rod

I think most all brands operate like this brand. There is supposed to be a small air gap at the top, the white area in this cut away pic. This is intended to keep floating debris away from the needle valve.

If you depress that needle valve after you install it, the air gap vents out and you pull any debris, like teflon tape shards into the needle valve and they leak from minute one.

There are two pressure ratings on a vent. The operating pressure, and the shutoff pressure. Depending on which model you have, make sure the shut off pressure exceeds the max pressure you run the system at.

Joe Mattiello

When system is operating, can you hear air in the system? Is the PRV set and maintaining 12psi? Did anything else change in the system? Close the vent by tightening cap, and call tech support at 401-942-8000.