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!