I'm getting a small leak (the occasional drip) from the tap on an isolation
valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious isolation valve
with handle on one side and something which looks like an isolation valve
but has a hex nut where I would expect a slotted screwdriver fitting or a
handle.

A quick check shows that the hex nut will go through more than a quarter
turn and is currently turned as far clockwise as it will go.
I'm wary of turning it too far anti-clockwise just in case it's going to
come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come across an
isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully anti-clockwise
will it shut off the system or will it just fall out?

Alan

--
email ~= s/nospam//

Alan wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious isolation
valve with handle on one side and something which looks like an
isolation valve but has a hex nut where I would expect a slotted
screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will go.
I'm wary of turning it too far anti-clockwise just in case it's going
to come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall out?

Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


--
Adam

ARWadsworth wrote:

Alan wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious isolation
valve with handle on one side and something which looks like an
isolation valve but has a hex nut where I would expect a slotted
screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will go.
I'm wary of turning it too far anti-clockwise just in case it's going
to come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall out?

Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can simply turn off
the water supply and disconnect the leaking isolation valve and there won't
be a back-flow of water from the double chweck valve end?

Alan

--
email ~= s/nospam//

On 06/10/2010 10:55, Alan wrote:

So IIUC, this is what I think of as a one-way valve so I can simply turn off
the water supply and disconnect the leaking isolation valve and there won't
be a back-flow of water from the double chweck valve end?

Correct. You might find this helpful:
http://www.makewrite.demon.co.uk/SealedCH.html

--
Andy

In article ,
"ARWadsworth" writes:
Alan wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious isolation
valve with handle on one side and something which looks like an
isolation valve but has a hex nut where I would expect a slotted
screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will go.
I'm wary of turning it too far anti-clockwise just in case it's going
to come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall out?

Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.

The nut is designed to allow testing that both of the double check
valves are working - there's one either side of it. It should be left
tighened up normally, and should not leak.

The braided hose should not be left in place except when you're topping
up the heating system. With the hose removed, no water should leak
back out of that valve, and if you do undo that nut, no water should
leak out of that either (save for an initial drip because the cavity
it goes into will contain static water, but it shouldn't carry on
dripping indefinitely). If the double check valve leaks from either
point, it should be replaced. This can probably wait until you are next
having the heating serviced - it's probably not an emergency unless
it starts leaking fast. With the hose in place, it's not possible
to say if the valve has failed of not, as it may be preventing enough
pressure difference to fully shut off the double check valve.

IME, the guts of these valves are destroyed if they ever get frozen.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andy Wade wrote:

On 06/10/2010 10:55, Alan wrote:

So IIUC, this is what I think of as a one-way valve so I can simply turn
off the water supply and disconnect the leaking isolation valve and there
won't be a back-flow of water from the double chweck valve end?

Correct. You might find this helpful:
http://www.makewrite.demon.co.uk/SealedCH.html


Thanks,

Alan

--
email ~= s/nospam//

John Rumm wrote:
On 06/10/2010 10:55, Alan wrote:
ARWadsworth wrote:

wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious
isolation valve with handle on one side and something which looks
like an isolation valve but has a hex nut where I would expect a
slotted screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will
go. I'm wary of turning it too far anti-clockwise just in case
it's going to come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall
out? Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can simply
turn off the water supply and disconnect the leaking isolation valve
and there won't be a back-flow of water from the double chweck valve
end?


The double check valve lets water flow into the CH system from the
mains, but prevents its return. So you could remove the flexible
connection, and with the the tap closed on the right, no water will
flow from either side.

Obviously you can't remove either valve from the fixed piping without
water escaping since the valve is all that is holding it back.

But he can turn off the mains cold water and then remove/replace the leaking
isolation valve.

--
Adam

John Rumm wrote:

On 06/10/2010 15:38, ARWadsworth wrote:
John wrote:
On 06/10/2010 10:55, Alan wrote:
ARWadsworth wrote:

wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious
isolation valve with handle on one side and something which looks
like an isolation valve but has a hex nut where I would expect a
slotted screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will
go. I'm wary of turning it too far anti-clockwise just in case
it's going to come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall
out? Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can simply
turn off the water supply and disconnect the leaking isolation valve
and there won't be a back-flow of water from the double chweck valve
end?


The double check valve lets water flow into the CH system from the
mains, but prevents its return. So you could remove the flexible
connection, and with the the tap closed on the right, no water will
flow from either side.

Obviously you can't remove either valve from the fixed piping without
water escaping since the valve is all that is holding it back.

But he can turn off the mains cold water and then remove/replace the
leaking isolation valve.

Not sure which isolation valve you mean? In the original photo I can
only see two valves; the tap on the right and the double check on the
left unless I have missed something? You won't be able to take either of
those off the pipework without getting wet! The only bit you can safely
disconnect is the braided flexy connection.



The tap on the right (with the handle) is the one I want to change. Now I'm
told that the other (which I didn't recognise) is a non-return valve I can
just shut off the water and disconnect it without the entire CH system
draining onto the floor ;-)

Thanks to all

Alan
--
email ~= s/nospam//

John Rumm wrote:
On 06/10/2010 15:38, ARWadsworth wrote:
John wrote:
On 06/10/2010 10:55, Alan wrote:
ARWadsworth wrote:

wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious
isolation valve with handle on one side and something which looks
like an isolation valve but has a hex nut where I would expect a
slotted screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will
go. I'm wary of turning it too far anti-clockwise just in case
it's going to come unscrewed, fall out and coverthe floor in
water Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall
out? Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can simply
turn off the water supply and disconnect the leaking isolation
valve and there won't be a back-flow of water from the double
chweck valve end?


The double check valve lets water flow into the CH system from the
mains, but prevents its return. So you could remove the flexible
connection, and with the the tap closed on the right, no water will
flow from either side.

Obviously you can't remove either valve from the fixed piping
without water escaping since the valve is all that is holding it
back.

But he can turn off the mains cold water and then remove/replace the
leaking isolation valve.

Not sure which isolation valve you mean? In the original photo I can
only see two valves; the tap on the right and the double check on the
left unless I have missed something? You won't be able to take either
of those off the pipework without getting wet! The only bit you can
safely disconnect is the braided flexy connection.

The valve on the right (I assumed the one with the plastic tray underneath
it catching the drips needed replacing). However the OP could have moved the
tray for the photo!

Once the mains water stop tap is turned off, there is no reason why it
cannot be removed and replaced (other than the standing water in the
pipework if the cold taps in the house are not opened up)

The OP certainly cannot remove the double check valve without draining his
radiators.

--
Adam

John Rumm wrote:

On 06/10/2010 16:19, Alan wrote:
John Rumm wrote:

On 06/10/2010 15:38, ARWadsworth wrote:
John wrote:
On 06/10/2010 10:55, Alan wrote:
ARWadsworth wrote:

wrote:
I'm getting a small leak (the occasional drip) from the tap on an
isolation valve which is part of the top-up for the CH system.

The top-up is a simple flexible connection with an obvious
isolation valve with handle on one side and something which looks
like an isolation valve but has a hex nut where I would expect a
slotted screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more than a
quarter turn and is currently turned as far clockwise as it will
go. I'm wary of turning it too far anti-clockwise just in case
it's going to come unscrewed, fall out and coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not come
across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just fall
out? Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can simply
turn off the water supply and disconnect the leaking isolation valve
and there won't be a back-flow of water from the double chweck valve
end?


The double check valve lets water flow into the CH system from the
mains, but prevents its return. So you could remove the flexible
connection, and with the the tap closed on the right, no water will
flow from either side.

Obviously you can't remove either valve from the fixed piping without
water escaping since the valve is all that is holding it back.

But he can turn off the mains cold water and then remove/replace the
leaking isolation valve.

Not sure which isolation valve you mean? In the original photo I can
only see two valves; the tap on the right and the double check on the
left unless I have missed something? You won't be able to take either of
those off the pipework without getting wet! The only bit you can safely
disconnect is the braided flexy connection.



The tap on the right (with the handle) is the one I want to change. Now
I'm told that the other (which I didn't recognise) is a non-return valve
I can just shut off the water and disconnect it without the entire CH
system draining onto the floor ;-)

Yup, disconnect the flexy hose. The double check on the left will keep
the water in the CH system. (you may spill half a cup out of the hose!)

The valve with the knob you can change once you have turned off the
mains cold water. Again if you drop the pressure a bit at a tap, and
then endure the other taps are off, you can do a quick swap like for
like without draining everything down.


Went to try changing the isolation valve (tap) - turned off the mains,
checked no flow through taps and disconnected the flexible hose at the tap
end - water poured out from the flexy hose

Fortunately I was paranoid enough to have been prepared (with plasic sheet
and bowl) so no harm done.

Looks like the double check valve is also naff so now it's down to draining
the system and replacing both valves

Alan

--
email ~= s/nospam//

Alan wrote:
John Rumm wrote:

On 06/10/2010 16:19, Alan wrote:
John Rumm wrote:

On 06/10/2010 15:38, ARWadsworth wrote:
John wrote:
On 06/10/2010 10:55, Alan wrote:
ARWadsworth wrote:

wrote:
I'm getting a small leak (the occasional drip) from the tap
on an isolation valve which is part of the top-up for the CH
system.

The top-up is a simple flexible connection with an obvious
isolation valve with handle on one side and something which
looks like an isolation valve but has a hex nut where I would
expect a slotted screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more
than a quarter turn and is currently turned as far clockwise
as it will go. I'm wary of turning it too far anti-clockwise
just in case it's going to come unscrewed, fall out and
coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not
come across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just
fall out? Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can
simply turn off the water supply and disconnect the leaking
isolation valve and there won't be a back-flow of water from
the double chweck valve end?


The double check valve lets water flow into the CH system from
the mains, but prevents its return. So you could remove the
flexible connection, and with the the tap closed on the right,
no water will flow from either side.

Obviously you can't remove either valve from the fixed piping
without water escaping since the valve is all that is holding it
back.

But he can turn off the mains cold water and then remove/replace
the leaking isolation valve.

Not sure which isolation valve you mean? In the original photo I
can only see two valves; the tap on the right and the double check
on the left unless I have missed something? You won't be able to
take either of those off the pipework without getting wet! The
only bit you can safely disconnect is the braided flexy connection.



The tap on the right (with the handle) is the one I want to change.
Now I'm told that the other (which I didn't recognise) is a
non-return valve I can just shut off the water and disconnect it
without the entire CH system draining onto the floor ;-)

Yup, disconnect the flexy hose. The double check on the left will
keep the water in the CH system. (you may spill half a cup out of
the hose!)

The valve with the knob you can change once you have turned off the
mains cold water. Again if you drop the pressure a bit at a tap, and
then endure the other taps are off, you can do a quick swap like for
like without draining everything down.


Went to try changing the isolation valve (tap) - turned off the mains,
checked no flow through taps and disconnected the flexible hose at
the tap end - water poured out from the flexy hose

Fortunately I was paranoid enough to have been prepared (with plasic
sheet and bowl) so no harm done.

Looks like the double check valve is also naff so now it's down to
draining the system and replacing both valves

Alan

Did you say something that rhymed with Clucking Bell when the water poured
out?

--
Adam

In article ,

Went to try changing the isolation valve (tap) - turned off the mains,
checked no flow through taps and disconnected the flexible hose at the tap
end - water poured out from the flexy hose

Fortunately I was paranoid enough to have been prepared (with plasic sheet
and bowl) so no harm done.

Looks like the double check valve is also naff so now it's down to draining
the system and replacing both valves

Isn't that always the way.

To avoid this sort of problem my system has a 1/4 turn isolating valve
on both the mains side and the C/H side.

Also, to make it easier to drain down the system and to inject
inhibitor, I have an open port (via valve) on the system side and the
check valve on the mains side (flipped to correct the orientation).

As you're draining down anyway this may be a sensible change to
incorporate.

If you fancy a bigger chore, it may be time to shift the filling point,
above that rad isn't the most inconspicuous spot.
--
fred
FIVE TV's superbright logo - not the DOG's, it's ********

ARWadsworth wrote:

Alan wrote:
John Rumm wrote:

On 06/10/2010 16:19, Alan wrote:
John Rumm wrote:

On 06/10/2010 15:38, ARWadsworth wrote:
John wrote:
On 06/10/2010 10:55, Alan wrote:
ARWadsworth wrote:

wrote:
I'm getting a small leak (the occasional drip) from the tap
on an isolation valve which is part of the top-up for the CH
system.

The top-up is a simple flexible connection with an obvious
isolation valve with handle on one side and something which
looks like an isolation valve but has a hex nut where I would
expect a slotted screwdriver fitting or a handle.

A quick check shows that the hex nut will go through more
than a quarter turn and is currently turned as far clockwise
as it will go. I'm wary of turning it too far anti-clockwise
just in case it's going to come unscrewed, fall out and
coverthe floor in water

Here's a photo of the set up
http://tinyurl.com/2az5hwt
The offending item is on the left - here's a close up photo
http://tinyurl.com/28cnbpx

I've had a quick look through various web-sites but I've not
come across an isolating valve looking like this.

Can someone enlighten me please - if I turn the nut fully
anti-clockwise will it shut off the system or will it just
fall out? Alan

It's a double check valve.
http://www.screwfix.com/prods/96336/

I would not turn the nut fully anti-clockwise.


So IIUC, this is what I think of as a one-way valve so I can
simply turn off the water supply and disconnect the leaking
isolation valve and there won't be a back-flow of water from
the double chweck valve end?


The double check valve lets water flow into the CH system from
the mains, but prevents its return. So you could remove the
flexible connection, and with the the tap closed on the right,
no water will flow from either side.

Obviously you can't remove either valve from the fixed piping
without water escaping since the valve is all that is holding it
back.

But he can turn off the mains cold water and then remove/replace
the leaking isolation valve.

Not sure which isolation valve you mean? In the original photo I
can only see two valves; the tap on the right and the double check
on the left unless I have missed something? You won't be able to
take either of those off the pipework without getting wet! The
only bit you can safely disconnect is the braided flexy connection.



The tap on the right (with the handle) is the one I want to change.
Now I'm told that the other (which I didn't recognise) is a
non-return valve I can just shut off the water and disconnect it
without the entire CH system draining onto the floor ;-)

Yup, disconnect the flexy hose. The double check on the left will
keep the water in the CH system. (you may spill half a cup out of
the hose!)

The valve with the knob you can change once you have turned off the
mains cold water. Again if you drop the pressure a bit at a tap, and
then endure the other taps are off, you can do a quick swap like for
like without draining everything down.


Went to try changing the isolation valve (tap) - turned off the mains,
checked no flow through taps and disconnected the flexible hose at
the tap end - water poured out from the flexy hose

Fortunately I was paranoid enough to have been prepared (with plasic
sheet and bowl) so no harm done.

Looks like the double check valve is also naff so now it's down to
draining the system and replacing both valves

Alan

Did you say something that rhymed with Clucking Bell when the water poured
out?


Actually it was more like Go Hit!

--
Alan

email ~= s/nospam//

In article ,
John Rumm writes:

If you are feeling brave, leave the flexy connected at both ends, and
undo to union nut for the double check valve, while keeping it pushed
against its stub of pipe with the other hand. Once the nut is free,
quickly swap the DC valve for a new one[1], and do the nut up again. As
long as the CH is off, and you have bled a litre of water out of a rad
somewhere, you won't lose much more.

Need to drain enough so pressure guage shows zero.

Just make sure you have the replacement bits easily to hand and in the
right state to use!

[1] Pull valve off, thumb over pipe end, pick up new valve and repeat.
Push valve against pipe stub while tightening union nut.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

In article ,
fred writes:
If you fancy a bigger chore, it may be time to shift the filling point,
above that rad isn't the most inconspicuous spot.

Try to keep it so you are within line-of-sight of the pressure guage
whilst filling system. Another option would be to add another
pressure guage at the filling point.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]