Fill valve replacement advice

David Nadle

I add water to my boiler by slightly opening a ball valve. I know ball valves are supposed to be on-off and not for flow control, but that's how the boiler was installed 7 years ago. The seal has now failed in a way so that water leaks past the closed ball and slowly floods the boiler. Before I replace it I thought I'd ask for advice. Would you go with another ball valve or something different?

Gordy

Pics of present boiler piping helpful.
Shut off valve before, and after pressure reducing valve to isolate, and replace in future also.

You say you leave the ball valve slightly open does the system leak to constantly have to add water?

Hap_Hazzard

I'd use a globe valve. They're designed for throttling. I'd also use a threaded one and install a union on the downstream side. This avoids any potential damage from heating the valve and makes it easier to replace in the future.

When you're adding water to the boiler, try to open the valve all the way as much as possible. Although they're intended for throttling, being partially open can allow impurities to accumulate inside the valve body, and if they get stuck between the disc and seat they can make it leak.

Also make sure the valve isn't mounted where live steam can enter it. Having a ball valve fail like this is a little unusual, so make sure it didn't have a reason to.

Gordy

My bad didn't see this was a steam boiler.

Abracadabra

David Nadle said:

I add water to my boiler by slightly opening a ball valve.

Why do you "slightly" open it and not open it completely and then shut it off completely?

KC_Jones

Another question that comes to my mind is how often do you have to add water to your steam boiler that this valve failed in 7 years? Under any circumstance that seems really short for a ball valve. Are you adding a lot of water to the boiler? I will third the opening of the valve, open it all the way there really is no reason to throttle that valve. Open it fill to the appropriate level then shut it off.

David Nadle

Thanks for the replies. I agree that it's seems very strange to have the ball valve fail this way. The answer to how often I add water is.. not that often. Every two weeks during the heating season I drain a quart or so from the bottom and refill with fresh. A small amount of water is lost through the vents during the coldest months but I don't think the makeup rate is excessive.

Gordy, I don't leave the ball valve cracked open. It's just that when I do open it I rarely open it fully.

The reason I throttle is that I'm not always adding the water to a cold boiler and don't want to shock it. This is one pipe steam with the return drops near the boiler. The installers piped the water feed into a drop, above the water line. This was smart, I think, as it further protects the boiler from thermal shock. But I guess there's a possibility that one side of the valve is exposed to steam.

Strategically, I'd rather be hard on the valve and gentle on the boiler. I wonder if any of my clarifications above give you any new ideas.

David Nadle

I finally got around to changing out the bad valve...for another ball valve. Quality sweat-on globe valves seem to have become rare and expensive.

The plastic seat got dislodged somehow and there's a clear gap.

I thought of another good reason to throttle the feed water. Cold skimming.