water pressure tank questions...

[Glen A Stromquist]

Lots of good info on this while googling, but lots of conflicting advice as well so here goes...

My water system consists of a in-ground cistern that gravity feeds a pump in my basement. The pump has a small pressure tank directly on top of it, I'd say about 24" high and 12-14" across. Typically I hear the pump kick in one or twice per toilet flush etc.. Over the past 12 years (since I had the home built) I've had to add some air to the valve on top of the pump when I heard the pump kicking on more than a few times when a toilet was flushed, I'm not sure how much but after adding a few psi it would clear up, and adding to much actually made it worse.

Well lately it has been getting bad again, but this time no matter what I add it seems the same, as well there is water coming out the air valve when I check the pressure. I shut the system off and drained the tank, then turned the the pump back on without adding air and I was getting no water out the valve but the pressure was going up to about 40 lbs psi when the pump was running and kicking back in in the low 30's. When I tried to play with the pressures again water started coming out the valve again.

So I'm pretty sure the tank is kaput, and I'm thinking I should get a bigger one that sits on the floor to reduce the pump starting so often. However I asked the "hardware guy" one day a while ago and he explained that a bigger tank makes no difference, as the pump will kick on when the pressure drops to X, and that will be the same time whether the tank is big or small. Makes no sense to me as I was talking to someone else who said they had a tank about 3' tall and it was 5 minutes of the taps running before the pump kicked in, definatly not what I experience with the small tank.

So I'm hoping someone here can help me with:

Is my tank kaput given water is coming out the air valve?

Am I prolonging my pump life getting a bigger tank?

thanks in advance!

[Spud]

Hi Yes the air and water are separate on your type tank so no water should come out air valve Yes get a bigger one not only so it doesn't run as often But so it runs longer short runs are as bad pressure is still going to be the same when it drops to x pump will kick in just takes longer to get to x how big ? they have charts for this Spud

[Harry K]

Yes, I would replace the tank or, if the existing tank is too much a part of the pump system, just ignore it and add another tank. As for pressure, you should have it set to have 20psi difference between cut-in and cut-out, i.e., 30/50 or 40/60.

Harry K

[Bob S.]

Probably. There is a rubber bladder inside the tank that has burst. Most, but not all, bladders are replaceable. However, finding one locally is usually impossible so you would probably have to order one from the manufacturer. Also the inside of the tank is usually bare metal so rust has probably started. Better to replace the tank.

Your comments about adding air is a good indication why the bladder ruptured. Normal operation is air inside the tank compresses as the bladder fills with water. The water pressure plus the air pressure operates the pressure switch turning the pump on and off. If your tank leaks air, the bladder has to stretch much farther than it was intended, leading to failure. Always maintain the air pressure to specs (usually around 27 psi with the tank empty of water) to get the max life out of the new tank.

Yes. What you were told is true but misleading. All tanks, regardless of size, operate the same way and at the same pressures. However the volume of water inside the tank varies. A larger tank will cause the pump to run longer to fill it up, but will also lengthen the time between pump startups. Like most motors, getting up to speed is hard but once there running is easy. The less start/stops your pump does, the longer it will last.

Bob S.

[Gary Slusser]

"Bob S." wrote

I have to disagree. The 27 psi is not correct. The air pressure with no water in the tank is set at 1-2 psi less than the cut-in pressure setting of the pressure switch.

Also, most bladders are not replaceable. And actually the two largest manufacturers of well pump pressure tanks, don't have a one.

Gary Quality Water Associates

Bulletin Board

[Harry K]

Even on the tanks with a replaceable bladder I would prefer buying the entire tank rather than install just the bladder. It isn't a fun job.

All tanks do -not- operate at the same pressure. Also all tanks do not have a bladder. Residential systems usually are set to one of 3 settings 40-60 (common), 30-50 (not as common but o.k.), 20-40 (unusual and I wouldn't do it). Some are set for higher pressures but it is not recommended for residential use as it causes undue wear on fixtures.

Gary is correct on the pre-charge setting.

Harry K

[Harry K]

I should correct that about ignoring the old tank. The system will work just fine with it in the system, but if it has a blown bladder you could have rust and bad water in it.

Harry K

[Glen A Stromquist]

thanks all..

I ended up buying a 33 gal tank yesterday, installing was a snap with a few elbows and reducers and a couple of feet of high pressure hose. One thing I did notice was that the existing tank was reduced to 3/4" pipe feeding into the "T", so I reduced the 1" coming out of the new tank to

3/4 as well. In hindsight I could have taken the reducer off of the pump end and had 1" plumbing from the tank to the pump, but I'm not sure if this make any difference. The good news is that I barely hear the pump kick on anymore, the bad news is that there are drops of water leaking out the bottom of the tank somwhere, so out it comes tonight if I get time to see where the leak is, I cinched the fittings up pretty snug and used teflon tape on all the joints, so I'm thinking it's got to be on the tank itself.

I also have a couple of other questions...

Should I remove the reducers and have 1" plumbing from the tank to the "T", and should I use steel pipe rather than high pressure hose?

The tank I bought was pre charged to 28 psi, I can't see the settings on the pump but it reads 40 psi when the pump has stopped. I'm assuming that this means the pump is set at 20-40, so should I drop the pressure to 18psi or change the pump settings? I can't see anything on the pump but I'm assuming its under a small cover off to the side.

thanks again for all your help

[Bob S.]

Ok, a wording error. What I meant to say is all tanks (residential per the OP's description)operate in the same -range- of pressures.

I never said all tanks do.

Precharge values given by the manufacturer take this into account. In the 30-50 range, specified precharge is 28 (2 psi less than 30). Since the OP stated his pump turn on was in the low 30's, I picked the

30-50 range(which in this area is the most common BTW). So we all were saying the same thing.

Bob S.