The check valve at the tank is so that house pressure does not put pressure
on the well system when the pump is off. The check valve at the pump is to
keep water in the well piping so you don't pump air every time the pump
starts.

"Harry K" wrote in message
ups.com...

Bob wrote:
If a check valve at the pump is bad, and a check valve at the tank
isn't,
then any air hole between the two will allow the water to drain back
down
the pipe.

"Harry K" wrote in message
ups.com...

Bob wrote:
If you don't have a pump above ground, and you have wires going down
the
well, then you have a submersible pump. Most likely the check valve
is
threaded to it.
It's possible that the vertical pipe is cracked, but not probable.
It
would
be spraying water out the crack when the pump is running. Can you
look
down
the well and check that?
It's more likely that you have a crack or pin hole in a section of
pipe
that
is underground.

"Dennis Straussfogel" wrote in message
...
In article
.com,
"Harry K" wrote:

Bob wrote:
Sounds like a bad check valve. The water is draining back down
the
pipe, and
when the pump kicks on, it sucks up air first.

"Dennis Straussfogel" wrote in message
...
I have an old (30 yr?) bladderless pressure tank on a shared
(4
houses)
well. It appears that over the last six months, air has been
entering
the tank somehow and ending up in the house water lines.
I've
been
bleeding air out of the tank about once every week to ten
days
and
that
corrects the problem temporarily. My question is: is there
any
way
(such
as a particular pump failure mode) that would allow this to
be
happening, or is the only thing that could be wrong is that
we
are
pumping the well faster than it can recover? (There's no
obvious
reason
to think the water table has dropped in the last year.)

When I lived in New Hampshire (The Granite State), there was
a
process
called "hydro-fracting" which involved dropping dry ice down
the
well
shock cooling the bedrock and opening up the fissures to
allow
faster
well recovery. I now live in Northern British Columbia (on
probably
clay
and gravel), so my second question is: if we are overpumping
the
well,
what can be done about it?

Thanks a lot for any information.

Denny

Nope. If he has a jet pump or a shallow well one on top of the
well
and the check valve (footvalve) was bad, he would be loosing the
prime.
If it is a submersible, it pumps from under the water level and
thus
can't suck air from there. The only place I can see air
entering
the
system at the pump location is from the snifter valve or a
flapper
valve on the side of the tank. Dissolved gases in the well
water??

Harry K

There's definitely nothing on the side of the pressure tank and no
obvious places (clamps, etc.) where air could be leaking in. I
suppose
the drop line may be cracked, which would reinforce some suspicion
that
the problem coincided with the onset of cold weather--metal
contracting
and opening up the crack.

My best guess is that it's a submersible pump in a deep well (The
story
is that the original owner paid CA$10,000.00 in the '70's to have
it
drilled--but there's some speculation he may have inflated that
figure
to rip off the people he was going to share the well with. Nice
guy.)
As
I said before, I wouldn't be surprised if this is a real
"half-fast"
system, just surprised it's lasted this long.

Thanks again,
Denny

It cannot be 'sucking' air in any section of pipe between the pump and
the tank. That is all pressurized and any leak is going to spray out,
not suck in. Same goes for any pipe on the delivery side of the tank.
The only way air can be sucked into a system is from before the pump.
My guess still remains as outgassing from the water or malfunctioning
snifter/float valve in the tank.

Sorta OT. I was on a community well (originally 4 houses), It was
down to 2 when I bought and somehow I wound up being an unpaid
serviceman for the system. Got tired of that and drilled my own well.
I have known others on community ones also and seems like all of them
have complaints.

Harry K


Good point. I overlooked that the OP does have such a set-up. I
really don't understand why it is done since it is redundant other than
in one circumstance. A failure of the checkvalve at the pump, install
one at the tank to obviate pulling the pump. Of course that does
result in air in the pipes problems.

Harry K