newer 20gal tank, only ~1.5 gal drawdown

[Charles City Mike]

I have learned a ton off of this forum so far, thanks!

Here's a few more questions I have:
Recently I began hearing a slight thump from under the house whenever the well pump cut on. Might just be pipe hammer. That in itself is not a problem except that it alerted me that my pump was cycling WAY too much.

It is a deep pump, sumberged, I have no other details. I never noticed this before, but until recently when we would loose power we still could take maybe 2 quick showers. Now, with a fully charged system I only get about 1.5 gallons! I have increased the pressure range for my on/off slightly to try and get more into the tank, which helped, but not much. It was cutting on about twice for every toilet flush, now maybe once. Using a hose normally it cuts on maybe every <30 secs; certainly not longer.

Tank: State Industries SPMD20, 20 gal, should be about 5-6 gals drawdown
Pres: Empty: 35 PSI, ON: 37 PSI, OFF: 64 PSI
(I got empty from where the gauge suddendly falls to 0 PSI with the system off.)

I DO get air pressure with the system off and drained, which roughly agrees with the 35 PSI above.

Quick additional question- where is the check valve in this type of system?

Please help me out before my pump grenades!
Mike

 

[Patrick88]

I assume you installed the same tank as your old one. When they build houses they use the smallest needed and cheapest for everything. I would have gone with a 40 gal equivalent, but they are sized to how many fixture and height. The rule of thumb i use is "you should be able to flush your toilet three times before the pump turns on". The check valve goes on the inlet side of your tank http://www.goulds.com/pdf/TTECHWP.pdf <<page 43

 

[Sponsor]

 

[Charles City Mike]

The tank is the original house tank from year 2000. Yes, the builders love using the cheapest stuff possible. If it goes out I will use a bigger one.

What is causing the low drawdown now, since the tank seems good? (Has air under pressure when drained.)

Thanks, Mike

 

[Bob NH]

If the bladder has a leak and there is water on the air side, that would cause low drawdown. Any water on the air side reduces the effective volume of the tank. That water will often not come out because the torn bladder may get jammed against the wall of the tank.

 

[Charles City Mike]

As the tank drains past 35 PSI (with pump off) water gauge pressure immediately drains to zero in about a second, is this normal???

Since there is some pressurized air which holds for extended periods of time (24 hours+) with the system drained I assumed that the bladder was intact, is this correct?

Mike

 

[Abikerboy]

You need to read "Check valve between pump and tank" thread. LOL!!!

 

[Valveman]

I believe BobNH is right about you bladder in the tank having water on top of it. To be sure, you can take out the air valve stem core and let all the air out of the tank. If only air comes out, then I am wrong. If water starts coming out after a bit, your tank is bad.

abikerboy is right about the above ground check valve causing the "thump" you are hearing. That thump is causing your system to see a shock of 10 times the pressure you see on your gauge. If your pump starts at 37 PSI, that "thump" causes your system sees a shock of 370 PSI. It also causes other problems as well.

 

[Rancher]

As the tank drains past 35 PSI (with pump off) water gauge pressure immediately drains to zero in about a second, is this normal???

This is normal for a bladder tank, because the water is pressurized by the aire in the bladder and when the tank runs out of water, there is nothing left to pressurize, hence rapid drop to zero.

Rancher

 

[Speedbump]

Rancher is right, but if the bladder has water on top, which will not necessarilly come out when you take out the schrader valves insert. But if water is above the bladder, the bladder is bad. What's left of the bladder can still cover the opening in the bottom of the tank and still act like a good tank.

bob...

 

[Charles City Mike]

Okay, thanks for all the help so far.

1) If I take out the valve core certainly all of the air will come out. If I then turn on the pump to presurize the bottom portion of the tank will I damage the (now empty) bladder by squishing it all the way to empty? If not, I can just do this and if no water comes out with even a little pressure in the water portion of the tank then I know for certain there is no water on top. (Right?) Just to make sure: Will slightly pump pressurizing the water portion of the chamber with NO air pressure screw up my tank???

2) I have read all of the "Check Valve" threads. There is not one under the house that I see, but maybe one at the top of the well column itself. It only thumps under certain flow conditions and then kind of lightly, which either tells me it's not that forceful or that it's not a force being created under the house- just being transmitted to the house (and must be addressed). I will try to find out if it is louder when I put my ear to the well head. It did sound a lot like the sound described in another thread, but not nearly as loud.

Will a couple of people please answer question #1. I want to be certain I don't screw up my tank! Thanks!

 

[Speedbump]

Do NOT do what you are planning to do to your tank. Simply push it to one side enough to see if it feels heavy. If it does, it's no good. If it's light, it may still be ok. If you let out the air and pressure it up, it will no longer be any good if it's a bladder tank. If it's one of those Well Mate Fiberglas tanks, it wouldn't matter.

bob...

 

[Charles City Mike]

Roger that. I won't do that. It should be nearly completely empty of water once the water pressure in the line drops to zero, thus relatively light. I will check that. I expect I might find it heavy.

Thanks, Mike

 

[Charles City Mike]

Well, I went down there and tapped on the tank, but couldn't hear any difference. I moved it and it was heavy even after being drained... about 20 gallons worth of heavy. Thing is, it must have had a little pinhole, so it never drained the pressurized air out, even when we lost power for a day or two. It just pushed the stagnant water out of the bottom of the air chamber. Once I managed to drag this thing out from under the house and open up the valve stem water came spraying out.

So, that answers my question about how it could have water above the a compromised diaphram, but still hold pressure- a pinhole.

Now to double check the check valve and reset my pressures.

Thanks!

 

[Bob NH]

Well, I went down there and tapped on the tank, but couldn't hear any difference. I moved it and it was heavy even after being drained... about 20 gallons worth of heavy. Thing is, it must have had a little pinhole, so it never drained the pressurized air out, even when we lost power for a day or two. It just pushed the stagnant water out of the bottom of the air chamber. Once I managed to drag this thing out from under the house and open up the valve stem water came spraying out.

So, that answers my question about how it could have water above the a compromised diaphram, but still hold pressure- a pinhole.

Now to double check the check valve and reset my pressures.

Thanks!

You didn't mention replacing the tank. Resetting the pressures comes after you install the new tank.

 

[Gary Slusser]

And since the pump didn't come on when the 37 psi setting was reached as you use water.... you still have the problem because a bad bladder can't cause that.

You could a plugged switch nipple, switch or any tubing to the switch.

With a submersible pump (in the well), you don't want additional check valves in the system; other than the one in/on the pump's outlet. They hide any water leaks between them and the pump.