New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

--
Mike W

visionset wrote:
New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

--
Mike W

Hi Mike,

Massive coincidence... I was just searching the forum as I have this
issue and your post appeared!! I am getting similar symptoms on my
newly installed Glow-Worm combi. I have an engineer visiting tomorrow
about a separate issue (loud rumbling) but I will ask him about this as
well. Watch this space!

J

In article ,
visionset writes:

New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

Possibly a deadleg of hot water pipework somewhere which is
full of air. The pressure increase in the cold supply as you
turn off a tap due to the momentum of the incoming water will
result in the air deadleg being compressed by water momentarily
flowing through the boiler. I don't know how the hot water store
works in that boiler, but maybe the air could be trapped in there?

--
Andrew Gabriel

On Fri, 15 Sep 2006 18:03:47 +0000, visionset wrote:


New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

In addition to AG's reply which I believe to be correct. You can switch
your boiler from intermittently heating the HW by turning the HW knob
fully anticlock and then back to where it was. This will save gas but
the HW will take longer to come through hot.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Fri, 15 Sep 2006 19:51:02 +0000, Andrew Gabriel wrote:

In article ,
visionset writes:

New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

Possibly a deadleg of hot water pipework somewhere which is
full of air. The pressure increase in the cold supply as you
turn off a tap due to the momentum of the incoming water will
result in the air deadleg being compressed by water momentarily
flowing through the boiler. I don't know how the hot water store
works in that boiler, but maybe the air could be trapped in there?

I have a deadleg as a temporary measure when swapping over from the stored
water conventional system to this one. As I have good ceiling and floor I
have capped off the hot supply from the old cylinder, so maybe it is
there. I'll try flexing the capped end down and whilst SWMBO runs the
taps bottom to top.
The boiler itself has a bleed program that does heating and hot water.
I've run this twice, so I'd expect internal components to be properly
bled. Shag, I've just thought - haven't bled the washing machine...

Thanks AG!

--
Mike W

On Fri, 15 Sep 2006 21:43:55 +0000, visionset wrote:

On Fri, 15 Sep 2006 19:51:02 +0000, Andrew Gabriel wrote:

In article ,
visionset writes:

New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

Possibly a deadleg of hot water pipework somewhere which is
full of air. The pressure increase in the cold supply as you
turn off a tap due to the momentum of the incoming water will
result in the air deadleg being compressed by water momentarily
flowing through the boiler. I don't know how the hot water store
works in that boiler, but maybe the air could be trapped in there?

I have a deadleg as a temporary measure when swapping over from the stored
water conventional system to this one. As I have good ceiling and floor I
have capped off the hot supply from the old cylinder, so maybe it is
there. I'll try flexing the capped end down and whilst SWMBO runs the
taps bottom to top.
The boiler itself has a bleed program that does heating and hot water.
I've run this twice, so I'd expect internal components to be properly
bled. Shag, I've just thought - haven't bled the washing machine...


The bleed program is for the primary side of the boiler.
There is not much pipework for any significant amount of air to get stick
in the domestic side.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

"Ed Sirett" wrote in message
news
On Fri, 15 Sep 2006 18:03:47 +0000, visionset wrote:


New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

In addition to AG's reply which I believe to be correct. You can switch
your boiler from intermittently heating the HW by turning the HW knob
fully anticlock and then back to where it was. This will save gas but
the HW will take longer to come through hot.


My parents WB combi (there is no HW storage in this one AFAIK but I would
have to check) also fires up when certain cold taps are used. This is only
caused when the outside tap or utility room cold taps are used and these are
the only taps between the combi and the main stop tap. No other taps cause
this "problem"

Is there any chance that these taps are causing a pressure drop that makes
the combi think HW has been called for?

Adam

On Sun, 17 Sep 2006 15:36:25 +0000, ARWadsworth wrote:


"Ed Sirett" wrote in message
news
On Fri, 15 Sep 2006 18:03:47 +0000, visionset wrote:


New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

In addition to AG's reply which I believe to be correct. You can switch
your boiler from intermittently heating the HW by turning the HW knob
fully anticlock and then back to where it was. This will save gas but
the HW will take longer to come through hot.


My parents WB combi (there is no HW storage in this one AFAIK but I would
have to check) also fires up when certain cold taps are used. This is only
caused when the outside tap or utility room cold taps are used and these are
the only taps between the combi and the main stop tap. No other taps cause
this "problem"

Is there any chance that these taps are causing a pressure drop that makes
the combi think HW has been called for?

I still think you need some sort of dead leg (or maybe very poorly clipped
pipework) after the boiler on the HW pipes to get this effect.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Sun, 17 Sep 2006 16:46:00 +0100, Ed Sirett wrote:

On Sun, 17 Sep 2006 15:36:25 +0000, ARWadsworth wrote:


"Ed Sirett" wrote in message
news
On Fri, 15 Sep 2006 18:03:47 +0000, visionset wrote:


New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

In addition to AG's reply which I believe to be correct. You can switch
your boiler from intermittently heating the HW by turning the HW knob
fully anticlock and then back to where it was. This will save gas but
the HW will take longer to come through hot.


My parents WB combi (there is no HW storage in this one AFAIK but I would
have to check) also fires up when certain cold taps are used. This is only
caused when the outside tap or utility room cold taps are used and these are
the only taps between the combi and the main stop tap. No other taps cause
this "problem"

Is there any chance that these taps are causing a pressure drop that makes
the combi think HW has been called for?

I still think you need some sort of dead leg (or maybe very poorly clipped
pipework) after the boiler on the HW pipes to get this effect.

I still have the problem
I looked up dead leg to ensure I understood you, could you clarify please
Ed?

I have tried all I can think of, and with knowledge of all my pipework, to
eradicate any air.

As I mentioned I do have a dead end section of pipe, which is horizontal,
but I am able to push this down to an angle sufficient (I'd have thought)
to expel the air.
I take it by your definition this is what you mean and that you expect
this to be full of air for the condition to be present?

If this dead leg is impossible to purge then I'll just have to wait till I
can get to the tee to modify the pipework. But at the moment there is too
much destruction waiting to made good elsewhere.

On Sun, 17 Sep 2006 20:57:43 +0000, visionset wrote:

On Sun, 17 Sep 2006 16:46:00 +0100, Ed Sirett wrote:

On Sun, 17 Sep 2006 15:36:25 +0000, ARWadsworth wrote:


"Ed Sirett" wrote in message
news On Fri, 15 Sep 2006 18:03:47 +0000, visionset wrote:


New Vaillant combi.
Any cold mains tap or valve is closed boiler seems to sense increase in
pressure and turns itself on. I imagine without investigating further
that it is heating the small hot water store as it does do intermittently
anyway. This happens every time so it isn't coincidence.
Any ideas?

In addition to AG's reply which I believe to be correct. You can switch
your boiler from intermittently heating the HW by turning the HW knob
fully anticlock and then back to where it was. This will save gas but
the HW will take longer to come through hot.


My parents WB combi (there is no HW storage in this one AFAIK but I would
have to check) also fires up when certain cold taps are used. This is only
caused when the outside tap or utility room cold taps are used and these are
the only taps between the combi and the main stop tap. No other taps cause
this "problem"

Is there any chance that these taps are causing a pressure drop that makes
the combi think HW has been called for?

I still think you need some sort of dead leg (or maybe very poorly clipped
pipework) after the boiler on the HW pipes to get this effect.

I still have the problem
I looked up dead leg to ensure I understood you, could you clarify please
Ed?

I have tried all I can think of, and with knowledge of all my pipework, to
eradicate any air.

As I mentioned I do have a dead end section of pipe, which is horizontal,
but I am able to push this down to an angle sufficient (I'd have thought)
to expel the air.
I take it by your definition this is what you mean and that you expect
this to be full of air for the condition to be present?

If this dead leg is impossible to purge then I'll just have to wait till I
can get to the tee to modify the pipework. But at the moment there is too
much destruction waiting to made good elsewhere.

I mean a part of the HW pipework which has not flow through it and thus
can harbour air. A way you can get the air out of a 'dead' branch is to
fit a quarter-turn service valve (aka Ball-o-fix) which you can use to
flush out the branch into a bucket/bowl/tray thus expelling any air.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

On Mon, 18 Sep 2006 22:18:47 +0100, Ed Sirett wrote:

I mean a part of the HW pipework which has not flow through it and thus
can harbour air. A way you can get the air out of a 'dead' branch is to
fit a quarter-turn service valve (aka Ball-o-fix) which you can use to
flush out the branch into a bucket/bowl/tray thus expelling any air.

Yeah of course, I'm juggling 20 jobs, my only excuse for being daft.

--
Mike W

I still think you need some sort of dead leg (or maybe very poorly clipped
pipework) after the boiler on the HW pipes to get this effect.


Ed,

Can I ask what you mean by 'poorly clipped pipework' in laymans terms?

Thanks

Stuart

On Tue, 19 Sep 2006 10:39:22 -0700, jks wrote:


I still think you need some sort of dead leg (or maybe very poorly clipped
pipework) after the boiler on the HW pipes to get this effect.


Ed,

Can I ask what you mean by 'poorly clipped pipework' in laymans terms?

Pipes that visibly move in repsonse to pressure variations, in this case
caused by turning taps on or off.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

I have now solved my three dead legs by putting valves on the end and
then bleeding air. (Thanks for the tip!) The combi boilder now does
not fire when I use the cold water system.

However, the boiler still seems to fire for a couple of seconds every
so often (haven't timed it but it seems to be about every hour).

My only explanation is that this is the pre-heat function keeping a
little reservoir of water warm. Am I correct? If so, does anyone know
how to turn this functionality off on a Glow-worm CXI combi??

Thanks

J

On Sun, 24 Sep 2006 09:52:42 -0700, jks wrote:


I have now solved my three dead legs by putting valves on the end and
then bleeding air. (Thanks for the tip!) The combi boilder now does
not fire when I use the cold water system.

However, the boiler still seems to fire for a couple of seconds every
so often (haven't timed it but it seems to be about every hour).

My only explanation is that this is the pre-heat function keeping a
little reservoir of water warm. Am I correct? If so, does anyone know
how to turn this functionality off on a Glow-worm CXI combi??

Thanks


Provided we are talking about a model with GCN 47-047-23/24/27 a GW nn
CXi Combi then look in the manual you'll see what to do to stop the
preheat function?



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html
Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards

a classic case of RTFM......Thanks Ed, I found it and it works.