We were having trouble getting water out of a large water tank and I'm
told it may be because of an air lock.
The tank and all pipes were drained because a visitor left a tap on
for a couple of weeks without turning off the stopcock by the tank.
There's an outlet pipe poking up 6 inches in the middle of the tank,
and a 1 inch inside diameter plastic pipe that runs downhill for 100
yards.
Then there is a T junction with one pipe going up to the kitchen sink
and the other going up to some handbasins. The vertical drop from the
bottom of the tank to the taps is about 10 feet.

There is no other water supply available to use to force air out of
the pipes.

There's several feet of water in the tank now, but none would come out
of the taps. I managed to rig up a large teapot with the spout
attached to each tap and sucked air out through a little hole in the
lid using a vacuum cleaner. After a lot of effort and lots of water
and air came out, I've got a reasonable flow of water from all the
taps, but not as good as it used to be. When it rains a bit more we'll
have a 20 foot head of water.

I don't really understand where the air would collect, since I imagine
the pipes are reasonably straight, and a 10 foot head of water should
surely push the air out. Without digging up the pipes covered in 50
year old tree roots I can't be sure what's there.
I would expect the air to rise up to the taps, but apparently not.
Does anyone know what was happening?

Matty F wrote:
We were having trouble getting water out of a large water tank and I'm
told it may be because of an air lock.
The tank and all pipes were drained because a visitor left a tap on
for a couple of weeks without turning off the stopcock by the tank.
There's an outlet pipe poking up 6 inches in the middle of the tank,
and a 1 inch inside diameter plastic pipe that runs downhill for 100
yards.
Then there is a T junction with one pipe going up to the kitchen sink
and the other going up to some handbasins. The vertical drop from the
bottom of the tank to the taps is about 10 feet.

There is no other water supply available to use to force air out of
the pipes.

There's several feet of water in the tank now, but none would come out
of the taps. I managed to rig up a large teapot with the spout
attached to each tap and sucked air out through a little hole in the
lid using a vacuum cleaner. After a lot of effort and lots of water
and air came out, I've got a reasonable flow of water from all the
taps, but not as good as it used to be. When it rains a bit more we'll
have a 20 foot head of water.

I don't really understand where the air would collect, since I imagine
the pipes are reasonably straight, and a 10 foot head of water should
surely push the air out. Without digging up the pipes covered in 50
year old tree roots I can't be sure what's there.
I would expect the air to rise up to the taps, but apparently not.
Does anyone know what was happening?

No. But it happens.

Had the same prob with my oil pipe. Tank up 1.5 meters above ground Pipe
goes down, under ground, and comes up to 6 inches above ground.

First ever fill, and no oil at either of the two exit pipes.

Had to SUCK the bloody pipes to get it through. Once pipe full of oil,
no more problems.

Can only think that capillary action means that any air in pipe causes
oil to stick to pipe!

"Matty F" wrote in message
...
We were having trouble getting water out of a large water tank and I'm
told it may be because of an air lock.
The tank and all pipes were drained because a visitor left a tap on
for a couple of weeks without turning off the stopcock by the tank.
There's an outlet pipe poking up 6 inches in the middle of the tank,
and a 1 inch inside diameter plastic pipe that runs downhill for 100
yards.
Then there is a T junction with one pipe going up to the kitchen sink
and the other going up to some handbasins. The vertical drop from the
bottom of the tank to the taps is about 10 feet.

There is no other water supply available to use to force air out of
the pipes.

There's several feet of water in the tank now, but none would come out
of the taps. I managed to rig up a large teapot with the spout
attached to each tap and sucked air out through a little hole in the
lid using a vacuum cleaner. After a lot of effort and lots of water
and air came out, I've got a reasonable flow of water from all the
taps, but not as good as it used to be. When it rains a bit more we'll
have a 20 foot head of water.

I don't really understand where the air would collect, since I imagine
the pipes are reasonably straight, and a 10 foot head of water should
surely push the air out. Without digging up the pipes covered in 50
year old tree roots I can't be sure what's there.
I would expect the air to rise up to the taps, but apparently not.
Does anyone know what was happening?


Is the tank sealed with a lid?

Are there any filters on the pipework, anywhere?

Did the water completely dry out when the taps were left running?

From what you describe, it sounds more like sediment has blocked the
pipework, rather than an air lock.

I take it that the little six inch pipe, sticking up in the middle of the
tank, is the actual outlet from the tank to the taps? If it is, then this
may have been left sticking up to stop any dirt from getting into the
system, but because the taps were left on, some muck has actually been
dragged into the pipes.

Maybe the pipework needs a good blow, rather than a suck. Can you get a
small piece of garden hose on one of the taps and blow through it. Even
borrow a set of bellows to give the pipes a real go blow through.

You might be able to make a small plunger that fits inside the outlet pipe
in the tank, and ram that down a few times to see if it helps to clear any
muck or air from the system. Nothing fancy. Just a metal washer and rubber
washer that fit quite tightly inside the pipe. Screw them on to a broom
handle and use it as a small plunger.

Just some simple ideas to try, I know, but they might help a little bit..

Matty F wrote:

We were having trouble getting water out of a large water tank and I'm
told it may be because of an air lock.
The tank and all pipes were drained [snip a lot]
Does anyone know what was happening?

I had a similar experience a few weeks ago, I had drained off a hot
water header tank to fit a new bath and basin.
Reconnected the basin, put a iso valve on the bath, which would be
refitted later that day, then turned back on the water.
The water flowed into the basin, but only very slowly.

Much head scratching later, and I chanced upon the probable theory -
there was around 6 feet of air in the 22mm pipe leading to the bath.
When the basin tap was put on, the water would flow slowly, but had
little pressure. My theory was that as the water came down from the
header tank, the air in the bath pipe was being compressed, then
exerting a pressure on the incoming water, so the flow was reduced to a
trickle.
A higher header tank, or a larger header tank would overcome this air
pressure, but the small one in the house wasnt enough.
And then, once the bath tap was connected, the air come out, and flow
was returned to normal, so the theory was about right, though it did
have me worried for a while that there was a blockage.
Alan.
--
To reply by e-mail, change the ' + ' to 'plus'.

On Dec 17, 8:44 pm, "BigWallop"
wrote:

Is the tank sealed with a lid?

It has a wooden shingle roof that lets any amount of air into it.

Are there any filters on the pipework, anywhere?

No filters.

Did the water completely dry out when the taps were left running?

The water in the tank was at the level of the outlet pipe, so I
imagine all of the pipework was completely full of air.

From what you describe, it sounds more like sediment has blocked the
pipework, rather than an air lock.

I take it that the little six inch pipe, sticking up in the middle of the
tank, is the actual outlet from the tank to the taps? If it is, then this
may have been left sticking up to stop any dirt from getting into the
system, but because the taps were left on, some muck has actually been
dragged into the pipes.

The wooden tank has a plastic lining and is fairly clean. I suppose if
there was any floating muck, that would have gone down the pipe. In
fact that is probably the answer to the problem.

Maybe the pipework needs a good blow, rather than a suck. Can you get a
small piece of garden hose on one of the taps and blow through it. Even
borrow a set of bellows to give the pipes a real go blow through.

Someone else used a bike pump with a non-return valve to blow into a
tap.
That had some effect, but the water flow soon stopped again.
The vacuum cleaner worked well, but the first reservoir I made was not
big enough and water was sucked right through the cleaner. I had to
take it apart and dry it out. A proper wet & dry vacuum cleaner would
be the answer.

You might be able to make a small plunger that fits inside the outlet pipe
in the tank, and ram that down a few times to see if it helps to clear any
muck or air from the system. Nothing fancy. Just a metal washer and rubber
washer that fit quite tightly inside the pipe. Screw them on to a broom
handle and use it as a small plunger.

It's a bit hard to get into the tank. I'd need to use a ladder, and
that would damage the plastic lining. The small inspection hatch is
not directly above the pipe, so a 10 foot long plunger wouldn't work.

Just some simple ideas to try, I know, but they might help a little bit..

I suspect there's a blockage at the T junction, and there are no
records of where that is. It's probably under the building where that
is one foot from the ground.

On Tue, 16 Dec 2008 21:58:27 -0800 (PST), Matty F wrote:

There is no other water supply available to use to force air out of
the pipes.

Air locks are funny things, the bouancy of the air lock forces the fluid
to flow around it in the pipe. You have to overcome that bouancy with a
pressure that is greater that it, to push the air through. This might be
acheiveable by getting as much flow as you can, all taps fully on. The
only other way is suck from the outlet or better pressurise from the
inlet.

Getting at the inlet end sounds a bit tricky now as it disappears under
20' of water. I'd wait until you have the full head then open everything
fully up and see if that is enough to push things through.

--
Cheers
Dave.

On Tue, 16 Dec 2008 21:58:27 -0800 (PST), Matty F
wrote:



I don't really understand where the air would collect, since I imagine
the pipes are reasonably straight, and a 10 foot head of water should
surely push the air out. Without digging up the pipes covered in 50
year old tree roots I can't be sure what's there.
I would expect the air to rise up to the taps, but apparently not.
Does anyone know what was happening?

Hi, unfortunately, no I don't, but similar problem yesterday.

How do these air locks come about and how do they cause flow problems?
Yesterday, our mains water flow decreased to a trickle. Usually, this
is due to a significant leak somewhere in the mains....we are on quite
an elevated site and many miles from the resevoir which feeds us and
there isn't much of a grid! Hence, any significant leak in about a 5
mile radius impacts us. So, rang the water company, fully expecting to
be told "there is a leak at xxxxxx. Is this likely to affect you?" and
they knew of nothing in the area. I'd already checked that our supply
pipe (which is about 200m long) was not leaking by checking the meter.
The CS person suggested turning the house stop tap off and on again
several times which I duly did and voila back to full flow rate. Now I
am puzzled why this worked and how the air lock arose in the first
place. There has been no recent work on any of the plumbing.

Any explanation appreciated.
Please reply to group - email address is not monitored
Ian

Ian wrote:
On Tue, 16 Dec 2008 21:58:27 -0800 (PST), Matty F
wrote:


I don't really understand where the air would collect, since I imagine
the pipes are reasonably straight, and a 10 foot head of water should
surely push the air out. Without digging up the pipes covered in 50
year old tree roots I can't be sure what's there.
I would expect the air to rise up to the taps, but apparently not.
Does anyone know what was happening?

Hi, unfortunately, no I don't, but similar problem yesterday.

How do these air locks come about and how do they cause flow problems?
Yesterday, our mains water flow decreased to a trickle. Usually, this
is due to a significant leak somewhere in the mains....we are on quite
an elevated site and many miles from the resevoir which feeds us and
there isn't much of a grid! Hence, any significant leak in about a 5
mile radius impacts us. So, rang the water company, fully expecting to
be told "there is a leak at xxxxxx. Is this likely to affect you?" and
they knew of nothing in the area. I'd already checked that our supply
pipe (which is about 200m long) was not leaking by checking the meter.
The CS person suggested turning the house stop tap off and on again
several times which I duly did and voila back to full flow rate. Now I
am puzzled why this worked and how the air lock arose in the first
place. There has been no recent work on any of the plumbing.

Any explanation appreciated.
Please reply to group - email address is not monitored
Ian

Same type of principle as rocking a car back and forward to get it out
being stuck in a muddy or snowy hole. Pressure from supply stops when it
is turned off and water with air trapped will move a bit. When supply
turned back on again pressure shifts it a bit and so on.

On Wed, 17 Dec 2008 17:16:40 +0000, Invisible Man
wrote:



Same type of principle as rocking a car back and forward to get it out
being stuck in a muddy or snowy hole. Pressure from supply stops when it
is turned off and water with air trapped will move a bit. When supply
turned back on again pressure shifts it a bit and so on.

Nice analogy. Thank you. I can see that.
I've never known of an air lock in mains pressure pipe before.
Live and learn!
Please reply to group - email address is not monitored
Ian

Ian wrote:
On Tue, 16 Dec 2008 21:58:27 -0800 (PST), Matty F
wrote:



I don't really understand where the air would collect, since I
imagine the pipes are reasonably straight, and a 10 foot head of
water should surely push the air out. Without digging up the pipes
covered in 50 year old tree roots I can't be sure what's there.
I would expect the air to rise up to the taps, but apparently not.
Does anyone know what was happening?

Hi, unfortunately, no I don't, but similar problem yesterday.

How do these air locks come about and how do they cause flow problems?
Yesterday, our mains water flow decreased to a trickle. Usually, this
is due to a significant leak somewhere in the mains....we are on quite
an elevated site and many miles from the resevoir which feeds us and
there isn't much of a grid! Hence, any significant leak in about a 5
mile radius impacts us. So, rang the water company, fully expecting to
be told "there is a leak at xxxxxx. Is this likely to affect you?" and
they knew of nothing in the area. I'd already checked that our supply
pipe (which is about 200m long) was not leaking by checking the meter.
The CS person suggested turning the house stop tap off and on again
several times which I duly did and voila back to full flow rate. Now I
am puzzled why this worked and how the air lock arose in the first
place. There has been no recent work on any of the plumbing.

I've had exactly the same experience. Turned off the stopcock to fit new
taps, turned it back on, only a trickle. Same cure, turned it on & off a
few times and it was fine. Still don't know why.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Wed, 17 Dec 2008 16:47:32 +0000, Ian wrote:

How do these air locks come about and how do they cause flow problems?

By blocking the pipe...

Your odd one, maybe there was a pressure reduction overnight when you
wouldn't notice that drew air into the system some how or air from repairs
elsewhere found it's way up to you. The turning on/off of the stop cock
I've been asked to do as well. It took quite a bit of "please listen to
what I am saying not what you expect me to say" to convince the CS
teletubbie that air was being sucked *into* the mains quite fast not that
I had no water or air was coming out.


--
Cheers
Dave.

On 18 Dec, 23:31, "Dave Liquorice"
wrote:
On Wed, 17 Dec 2008 16:47:32 +0000, Ian wrote:
How do these air locks come about and how do they cause flow problems?

By blocking the pipe...

Your odd one, maybe there was a pressure reduction overnight when you
wouldn't notice that drew air into the system some how or air from repairs
elsewhere found it's way up to you. The turning on/off of the stop cock
I've been asked to do as well. It took quite a bit of "please listen to
what I am saying not what you expect me to say" to convince the CS
teletubbie that air was being sucked *into* the mains quite fast not that
I had no water or air was coming out.

--
Cheers
Dave.

Try using a syphon to equalize the pressure from both sides? Get a
length of hose pipe long enough to go from the tank to the taps. Have
a tap/hose connector handy at the tap end. Stick the other end of the
hose in the tank and fix it there. Go to the tap end and suck to start
a syphone. When the water is flowing fix the hose to the tap using the
hose connector and open the tap. The water will try to reach the tank
level in the pipe and may dislodge the air or sludge. Might work?