Hot supply sputtering / gate valves


L

lister

Hi folks,

I had to change a sink today with no isolation valves on the taps, so
I had to shut off the water.

First turned cold off at rising main.

Looked in airing cupboard to be confronted by one tap like valve just
like the rising main, and three red wheel valves (gate valves?).

Couldn't work out which one stopped the hot, so turned em all off, and
ran a lot of hot taps until they slowed to a stop. All hunkey dorey.

After cutting the tap feed pipes, I was half way through fitting some
isolation valves when there was some ominous gurgling in the system
and a second later I got a four foot jet of water out of the hot pipe!
This cycle then kept occurring approx every 30 seconds or so while I
battled to fit the isolator!

After new sink in place I turned everything back on again. The problem
I now have is that the hot feed is spluttering / low pressure from
most hot taps in the house. Sometimes it's normal, sometimes it slows
to a trickle. I assume I have air in the system.

My questions therefore are:

1) If I leave the hot taps running will they sort themselves out?

2) Can I have gotten air in the cylinder? It is dangerous to turn the
cylinder on to heat if this is the case? Is there any way to tell?

3) The red gate valves don't seem to turn very far (maybe half a
turn). Is this right or have I knackered em?

Many thanks,
Lister
 
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G

Guest

lister said:
Hi folks,

I had to change a sink today with no isolation valves on the taps, so
I had to shut off the water.

First turned cold off at rising main.

Looked in airing cupboard to be confronted by one tap like valve just
like the rising main, and three red wheel valves (gate valves?).

Couldn't work out which one stopped the hot, so turned em all off, and
ran a lot of hot taps until they slowed to a stop. All hunkey dorey.

After cutting the tap feed pipes, I was half way through fitting some
isolation valves when there was some ominous gurgling in the system
and a second later I got a four foot jet of water out of the hot pipe!
This cycle then kept occurring approx every 30 seconds or so while I
battled to fit the isolator!

After new sink in place I turned everything back on again. The problem
I now have is that the hot feed is spluttering / low pressure from
most hot taps in the house. Sometimes it's normal, sometimes it slows
to a trickle. I assume I have air in the system.

My questions therefore are:

1) If I leave the hot taps running will they sort themselves out?

2) Can I have gotten air in the cylinder? It is dangerous to turn the
cylinder on to heat if this is the case? Is there any way to tell?

3) The red gate valves don't seem to turn very far (maybe half a
turn). Is this right or have I knackered em?

Many thanks,
Lister
There should be a vent pipe in the top of the cylinder running up to
overflow to the tank in the loft (assuming we are talking about traditional
house and system: I bow to other writers if not.), so air should work its
way out that way. If your pipes run a particularly circuitous route you may
have more trouble getting the air out. Sometimes there may be enough play
for you to shake the pipes a bit *with all the taps *turned off**, then you
may be lucky and hear the glugs in the tank as the bubbles work their way up
and out. If you try this with the taps on, the bubble will try to travel
down, but probably end up staying still.

The gate valves: http://en.wikipedia.org/wiki/Gate_valve should have
several turns on them and they are very often stuck. They are meant to be
fully open or fully closed. Sounds like yours were only partly open, and
are now covered in crud. If not fully open they can rattle - until crudded
at any rate -, but if turned out hard they get stuck, and commonly the end
snaps off next time you try to close them. They are very prone to getting
stuck and leaking yet very cheap to buy at your local plumbing suppliers.

What you should do is get yourself some new gate valves. Tie up the ball
valve on the loft tank - bungees are good for this - (especially if the
inlet has another stuck gate valve for the cold supply: if you need to
replace that one you will have to turn off the cold supply further back.),
and open all your hot taps until they stop, and leave them open for any
water that is suddenly released when you start replacing the valves. If you
have an old system you may have hassles replacing imperial sizes with
metric, in which case you may find it easier to replace the lengths of pipe
that have the valves in rather than trying to bodge old to new. If you have
managed to change a sink, you should be able to change these valves without
too much trouble - though working in confined cupboards full of pipes can
always present you with them! (Start with the highest valve to minimise any
spills.)

S
 
T

Tim Watts

Hi,

Hi folks,

I had to change a sink today with no isolation valves on the taps, so
I had to shut off the water.

First turned cold off at rising main.

Looked in airing cupboard to be confronted by one tap like valve just
like the rising main, and three red wheel valves (gate valves?).
Yes, almost certainly gate valves.
Couldn't work out which one stopped the hot, so turned em all off, and
ran a lot of hot taps until they slowed to a stop. All hunkey dorey.

After cutting the tap feed pipes, I was half way through fitting some
isolation valves when there was some ominous gurgling in the system
and a second later I got a four foot jet of water out of the hot pipe!
This cycle then kept occurring approx every 30 seconds or so while I
battled to fit the isolator!
Assuming a vented system:

The gate valve will *probably* have either stopped the cold tank filling
(and thus indirectly the hot tank) or it cut the feel from the cold to the
hot tank.

So, it sounds as if some air managed to get in and defeat the partiation
vacuum that was otherwise stopping the water coming out.
After new sink in place I turned everything back on again. The problem
I now have is that the hot feed is spluttering / low pressure from
most hot taps in the house. Sometimes it's normal, sometimes it slows
to a trickle. I assume I have air in the system.

My questions therefore are:

1) If I leave the hot taps running will they sort themselves out?
Usually.

2) Can I have gotten air in the cylinder? It is dangerous to turn the
cylinder on to heat if this is the case? Is there any way to tell?
Vented or unvented system?

If vented, it will fix itself. Unvented, no idea.



3) The red gate valves don't seem to turn very far (maybe half a
turn). Is this right or have I knackered em?
I thought they turned more than that - TBH used ball valves for so long,
I've forgotton.

BTW - next time,shut off the rising main, leave everything else open and
drain the HW tank via the lowest tap. Or get a pipe freeze kit :)
 
H

harry

Hi folks,

I had to change a sink today with no isolation valves on the taps, so
I had to shut off the water.

First turned cold off at rising main.

Looked in airing cupboard to be confronted by one tap like valve just
like the rising main, and three red wheel valves (gate valves?).

Couldn't work out which one stopped the hot, so turned em all off, and
ran a lot of hot taps until they slowed to a stop. All hunkey dorey.

After cutting the tap feed pipes, I was half way through fitting some
isolation valves when there was some ominous gurgling in the system
and a second later I got a four foot jet of water out of the hot pipe!
This cycle then kept occurring approx every 30 seconds or so while I
battled to fit the isolator!

After new sink in place I turned everything back on again. The problem
I now have is that the hot feed is spluttering / low pressure from
most hot taps in the house. Sometimes it's normal, sometimes it slows
to a trickle. I assume I have air in the system.

My questions therefore are:

1) If I leave the hot taps running will they sort themselves out?

2) Can I have gotten air in the cylinder? It is dangerous to turn the
cylinder on to heat if this is the case? Is there any way to tell?

3) The red gate valves don't seem to turn very far (maybe half a
turn). Is this right or have I knackered em?

Many thanks,
Lister
The gate valves are usually about 4 or 5 turns fully open to fully
shut. It's quite likely they are corroded up and can't be fully
opened/closed. Also the valve seats are quite likely corroded too &
the valve won't shut off tight.

You may have air in the sytem. Assuming you have a traditional tank
in the loft system. In the kitchen get a short piece of hose pipe and
join up the hot and cold taps. You may need assistance to hold the
hoses in place.
Turn on the hot tap and then the cold tap. High pressure mains water
will go into the hot sytem and displace any air. lesve it run for a
minute or so. Turn off the cold tap first and then the hot or you may
get a bit wet.
 
C

Chris J Dixon

Assuming a vented system:

The gate valve will *probably* have either stopped the cold tank filling
(and thus indirectly the hot tank) or it cut the feed from the cold to the
hot tank.

So, it sounds as if some air managed to get in and defeat the partiation
vacuum that was otherwise stopping the water coming out.
Which is perhaps just as well, since you could otherwise have
collapsed your hot tank!

Chris
 
H

harry

The gate valves are usually about 4 or 5 turns fully open to fully
shut.  It's quite likely they are corroded up and can't be fully
opened/closed. Also the valve seats are quite likely corroded too &
the valve won't shut off tight.

You may have air in the sytem.  Assuming you have a traditional tank
in the loft system.  In the kitchen get a short piece of hose pipe and
join up the hot and cold taps. You may need assistance to hold the
hoses in place.
Turn on the hot tap and then the cold tap.  High pressure mains water
will go into the hot sytem and displace any air. lesve it run for a
minute or so. Turn off the cold tap first and then the hot or you may
get a bit wet.- Hide quoted text -

- Show quoted text -
Oh, do this at the other taps in the house too if the problem persists.
 
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L

lister

The gate valves are usually about 4 or 5 turns fully open to fully
shut.  It's quite likely they are corroded up and can't be fully
opened/closed. Also the valve seats are quite likely corroded too &
the valve won't shut off tight.
Many thanks for all your replies guys. After reading that I had
another fiddle with the gate valves and managed to get the one
controlling the cold water feed to the cylinder all the way open. All
hot taps instantly fine again. Makes sense because they ran fine for a
few moments this morning before spluttering again which I guess is due
to the cylinder having a chance to fill full again overnight.

Looks like I'll have to look at replacing them at some point. Thanks
again.
 
L

lister

Tim Watts wrote:
Which is perhaps just as well, since you could otherwise have
collapsed your hot tank!

Chris
Sorry, can you eloborate just for my future safety! How can I collapse
the tank on a vented system?
 
D

Dave Liquorice

The gate valves: http://en.wikipedia.org/wiki/Gate_valve should have
several turns on them and they are very often stuck.
Yes, bastard things.
They are meant to be fully open or fully closed.
Not *fully* open, that is a guaranteed way for the crud/corrosion to
jam 'em up very firmly. You stand slightly more chance of them not
jamming if you fully open then close them half a turn or so. Also
it's a good idea to fully close and reopen them every so often, like
once a year.

If I ever take any of the gate valves out here they will be replaced
with full bore ball valves. Note "full bore", most ball valves are
not full bore and will restrict the flow, gate valves are full bore.
 
H

harry

Yes, bastard things.


Not *fully* open, that is a guaranteed way for the crud/corrosion to
jam 'em up very firmly. You stand slightly more chance of them not
jamming if you fully open then close them half a turn or so. Also
it's a good idea to fully close and reopen them every so often, like
once a year.

If I ever take any of the gate valves out here they will be replaced
with full bore ball valves. Note "full bore", most ball valves are
not full bore and will restrict the flow, gate valves are full bore.
It's not the fault of the vave design, it's the cheap and nasty metal
they'r made of.
Ball valves go exactly the same way if cheap and nasty.
 
D

Dave

Yes, bastard things.


Not *fully* open, that is a guaranteed way for the crud/corrosion to
jam 'em up very firmly. You stand slightly more chance of them not
jamming if you fully open then close them half a turn or so. Also
it's a good idea to fully close and reopen them every so often, like
once a year.
The advice on opening a valve fully and then closing it slightly applies
to any type of valve. If you can turn it, you know it is open, if you
can't, then you know it is closed.

Dave
 
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G

Guest

Dave Liquorice said:
Yes, bastard things.


Not *fully* open, that is a guaranteed way for the crud/corrosion to
jam 'em up very firmly. You stand slightly more chance of them not
jamming if you fully open then close them half a turn or so. Also
it's a good idea to fully close and reopen them every so often, like
once a year.
Yes, sorry, I was going to mention they needed to be backed off a fracton:
but not so much they get into the flow.

Cheers
S
 
G

Guest

The gate valves are usually about 4 or 5 turns fully open to fully
shut. It's quite likely they are corroded up and can't be fully
opened/closed. Also the valve seats are quite likely corroded too &
the valve won't shut off tight.
Many thanks for all your replies guys. After reading that I had
another fiddle with the gate valves and managed to get the one
controlling the cold water feed to the cylinder all the way open. All
hot taps instantly fine again. Makes sense because they ran fine for a
few moments this morning before spluttering again which I guess is due
to the cylinder having a chance to fill full again overnight.

Looks like I'll have to look at replacing them at some point. Thanks
again.


Watch out for crud in your taps if you let the cold tank right down - there
may have been stuff floating on it. Probably won't happen but if your tank
isn't fully covered you never know (I once got a CH pump choked with
polystyrene beads, when its header tank ran dry that had been covered with
a polystyrene sheet that had started to break up.)
 
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G

Guest

harry said:
The gate valves are usually about 4 or 5 turns fully open to fully
shut. It's quite likely they are corroded up and can't be fully
opened/closed. Also the valve seats are quite likely corroded too &
the valve won't shut off tight.

You may have air in the sytem. Assuming you have a traditional tank
in the loft system. In the kitchen get a short piece of hose pipe and
join up the hot and cold taps. You may need assistance to hold the
hoses in place.
Turn on the hot tap and then the cold tap. High pressure mains water
will go into the hot sytem and displace any air. lesve it run for a
minute or so. Turn off the cold tap first and then the hot or you may
get a bit wet.
Good idea Harry: must try to remember that.

S
 

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