expansion tank?

dpframing

I am a homeowner who doesn't know anything close to the pros, but I'm handy.

The other boiler I have is acting up now. Water is pouring (at the end of a cycle) out the pressure relief valve. I am thinking of first replacing the original undersized expansion tank that came with the boiler when it was installed in 2002.
It's half the size of an Extrol30#. The same thing happened last year to the other boiler and when I replaced that expansion tank with an Extrol 30# , and the spillage stopped.

Can I half-drain the system to install it? I can't remember what I did last year.
Thank you.

Alan (California Radiant) Forbes

You've just got to drain it below the x-tank level. Otherwise, you're gonna' take a bath.

ChrisJ

Alan (California Radiant) Forbes said:

You've just got to drain it below the x-tank level. Otherwise, you're gonna' take a bath.

As long as you relieve the pressure, shouldn't you be able to remove the old tank and quickly swap in a new one without much if anything coming out of the closed system?


Never done this on my own, but I helped a friend swap a tank out over 10 years ago and we expected a ton of water to come spewing out and instead absolutely nothing came out.

unclejohn

Add a nipple and a ball valve and you won't need to worry about it ever again.

haunt

Once the pressure is relieved from the system make sure that everything is closed again, so you won't let any air into the system. Have your new tank ready to go on as soon as you remove the old one. The water should stay put as long as no air gets in to replace the water. It's like that trick where you put a piece of paper on top of a glass of water and turn it over. Watch trick 2 here:
https://www.youtube.com/watch?v=yUQHyhYCuwI

BUT, be prepared in case the water didn't see the video.

ChrisJ

When we did this at a friends house, there was three of us. The plan was the one guy would pull the old tank away, the second would cover the hole with his thumb and the third (me) would come in with the new tank.

It didn't go that way as no one realized the old tank was full of water. The first guy picked the tank up, second guy put his thumb over the hole, first guy dropped tank back down because he couldn't hold it, second guy yelled "IT'S ON MY FINGA!!!!! (he's from Brooklyn)" and I was in tears. We finally pulled the tank away and nothing came out so we both stood there surprised but realized as haunt said, if air can't get in, water can't get out.

Swapped the new tank in and everyone was happy, even the thumb.

I wish we had a video camera going. Good memories.

JUGHNE

I would go with the nipple and ball valve as suggested above.

However, I would take all pressure off system, have the nipple/valve ready with a longer temp nipple on the discharge of the valve. Remove the tank and start screwing the short nip/valve in with the valve open. That way if water is draining most of it will go thru the valve until you have it hand tight and then can shut the valve off. The longer temp nipple is to straighten out the stream of water if any and maybe direct it to a bucket.

This has been done with pressurized water mains and NG riser stubs in the alleys that capped. This method is used with a minimal of gas escaping from a 10 PSI gas line. (Outside of course).