Hi all....i have a pressure loss on a combi heating system....the system is
stable when the heating is switched off....stable for over a week at 1.5
bar...but after a hour or so of activity on central heating there is a loss
.... a fairly big loss ...the trouble is is that i can't find the loss...i've
checked all radiators and all valves on those radiators...there is no sign
of any leakage to plaster work around the house....all radiators are
full...i bled them last week ...so where can it be....i've looked around the
boiler itself and have come up blank...no leaks to be found.

All help appreciated.

Simmmy

On Mon, 28 Mar 2005 09:12:38 +0000, Simmmy wrote:

Hi all....i have a pressure loss on a combi heating system....the system is
stable when the heating is switched off....stable for over a week at 1.5
bar...but after a hour or so of activity on central heating there is a loss
... a fairly big loss ...the trouble is is that i can't find the loss...i've
checked all radiators and all valves on those radiators...there is no sign
of any leakage to plaster work around the house....all radiators are
full...i bled them last week ...so where can it be....i've looked around the
boiler itself and have come up blank...no leaks to be found.

All help appreciated.

See FAQ.

--
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

Thanks for the reply....do you suspect a release valve or expansion tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

Thanks
"Ed Sirett" wrote in message
news
On Mon, 28 Mar 2005 09:12:38 +0000, Simmmy wrote:

Hi all....i have a pressure loss on a combi heating system....the system
is
stable when the heating is switched off....stable for over a week at 1.5
bar...but after a hour or so of activity on central heating there is a
loss
... a fairly big loss ...the trouble is is that i can't find the
loss...i've
checked all radiators and all valves on those radiators...there is no
sign
of any leakage to plaster work around the house....all radiators are
full...i bled them last week ...so where can it be....i've looked around
the
boiler itself and have come up blank...no leaks to be found.

All help appreciated.

See FAQ.

--
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

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and see if
the
pressure release valve blows at 3 bars ( don't go much above that whatever
happens ).
However, I expect your expansion tank has lost its air. Look back at the
various combi threads over the last 10 days or more.

Andy.

Thanks ... i have done what you said and looked back and came across this
post...
"Central Heating Boiler problem"



I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.




These are the very same problems i have had recently...this is what someone
recons the problem is

Expansion vessel is not working to absorb the water expansion

Is this a easy and inexpensive repair?



Thanks







"andrewpreece" wrote in message
...

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and see
if
the
pressure release valve blows at 3 bars ( don't go much above that whatever
happens ).
However, I expect your expansion tank has lost its air. Look back at the
various combi threads over the last 10 days or more.

Andy.

Thanks ... i have done what you said and looked back and came across this
post...
"Central Heating Boiler problem"



I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.




These are the very same problems i have had recently...this is what someone
recons the problem is

Expansion vessel is not working to absorb the water expansion

Is this a easy and inexpensive repair?




"andrewpreece" wrote in message
...

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and see
if
the
pressure release valve blows at 3 bars ( don't go much above that whatever
happens ).
However, I expect your expansion tank has lost its air. Look back at the
various combi threads over the last 10 days or more.

Andy.

"andrewpreece" wrote in message
...

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and see
if
the
pressure release valve blows at 3 bars ( don't go much above that whatever
happens ).

You could then try buying a new pressure relief valve as its very likley
that doing what you suggest will result in system dirt lodging under the
seat of the valve causing a slow drip which may not be curable:-(.
Never deliberately over pressure a relief valve on a system whuch has been
in use for any length of time.

I would suggest you fit a polythene freezer bag over the outlet pipe of the
relief valve with an elastic band to secure it. Then see if it collects
water in it when your boiler heats up. This will tell you if the water is
going out of the relief valve. Watch the pressure gauge after you have
charged the system while cold and switched it on to heat up the radiators.
An excessive pressure rise will indicate a lack of somewhere for the water
to expand into as the temperature rises. This means your expansion vessel
may have lost its gas precharge, it may have a blocked connector pipe
between vessel and system or it may never have been big enough in the first
place (more or less in that order)

"Simmmy" wrote in message
. uk...
Thanks ... i have done what you said and looked back and came across this
post...
"Central Heating Boiler problem"



I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.




These are the very same problems i have had recently...this is what
someone
recons the problem is

Expansion vessel is not working to absorb the water expansion

Is this a easy and inexpensive repair?




"andrewpreece" wrote in message
...

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion
tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and
see
if
the
pressure release valve blows at 3 bars ( don't go much above that
whatever
happens ).
However, I expect your expansion tank has lost its air. Look back at the
various combi threads over the last 10 days or more.

Andy.





I have no idea what it costs. You need to find your expansion vessel thingy,
possibly
painted red, about a foot or more across at the back of the combi, a bit
doughnut shaped.
Unscrew the cap on the bicycle valve attached to it ( gingerly ): if water
comes out the diaphragm
in the expansion vessel has leaked - time for a new expansion vessel. If air
comes out then check the pressure on it and pump it back up to what it
should be ( I confess I don't know ) with a
bicycle pump, and dab a bit of soapy water across the inlet to the valve to
see if it is leaking air.
If the vessel has leaked and you want to repair it yourself you may be able
to avoid the grief of dismantling the combi to get at the vessel by
attaching a new expansion vessel on the CH pipework at an appropriate place
elsewhere. You'll have to drain the CH down etc etc. Spare parts can be
bought on a number of websites, Google for more info. NB I am not an expert!
DYOR etc.

This question comes up every week without fail!

Andy.

Thanks...

Much appreciated.

Simmmy
"andrewpreece" wrote in message
...

"Simmmy" wrote in message
. uk...
Thanks ... i have done what you said and looked back and came across this
post...
"Central Heating Boiler problem"



I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.




These are the very same problems i have had recently...this is what
someone
recons the problem is

Expansion vessel is not working to absorb the water expansion

Is this a easy and inexpensive repair?




"andrewpreece" wrote in message
...

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion
tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and
see
if
the
pressure release valve blows at 3 bars ( don't go much above that
whatever
happens ).
However, I expect your expansion tank has lost its air. Look back at
the
various combi threads over the last 10 days or more.

Andy.





I have no idea what it costs. You need to find your expansion vessel
thingy,
possibly
painted red, about a foot or more across at the back of the combi, a bit
doughnut shaped.
Unscrew the cap on the bicycle valve attached to it ( gingerly ): if water
comes out the diaphragm
in the expansion vessel has leaked - time for a new expansion vessel. If
air
comes out then check the pressure on it and pump it back up to what it
should be ( I confess I don't know ) with a
bicycle pump, and dab a bit of soapy water across the inlet to the valve
to
see if it is leaking air.
If the vessel has leaked and you want to repair it yourself you may be
able
to avoid the grief of dismantling the combi to get at the vessel by
attaching a new expansion vessel on the CH pipework at an appropriate
place
elsewhere. You'll have to drain the CH down etc etc. Spare parts can be
bought on a number of websites, Google for more info. NB I am not an
expert!
DYOR etc.

This question comes up every week without fail!

Andy.

On Tue, 29 Mar 2005 00:18:25 +0100, andrewpreece wrote:




I have no idea what it costs. You need to find your expansion vessel thingy,
possibly
painted red, about a foot or more across at the back of the combi, a bit
doughnut shaped.
Unscrew the cap on the bicycle valve attached to it ( gingerly ): if water
comes out the diaphragm
in the expansion vessel has leaked - time for a new expansion vessel. If air
comes out then check the pressure on it and pump it back up to what it
should be ( I confess I don't know ) with a
bicycle pump, and dab a bit of soapy water across the inlet to the valve to
see if it is leaking air.
If the vessel has leaked and you want to repair it yourself you may be able
to avoid the grief of dismantling the combi to get at the vessel by
attaching a new expansion vessel on the CH pipework at an appropriate place
elsewhere. You'll have to drain the CH down etc etc. Spare parts can be
bought on a number of websites, Google for more info. NB I am not an expert!
DYOR etc.

This question comes up every week without fail!

Which is why we have a FAQ (with suggested answers).


--
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

I have looked outside at the outlet pipe and it suggests it has been
leaking....water round the pipe and also on the ground underneath.

Whats the course of action now?

"I would suggest you fit a polythene freezer bag over the outlet pipe of the
relief valve with an elastic band to secure it. Then see if it collects
water in it when your boiler heats up. This will tell you if the water is
going out of the relief valve".

I would'nt say there was a excessive rise in water pressure whilst the
heating is running....just a loss of pressure after it cools back
down...again i can find no leaks to any plaster work inside the house or at
any radiators and boiler.

Thanks


"John" wrote in message
...

"andrewpreece" wrote in message
...

"Simmmy" wrote in message
k...
Thanks for the reply....do you suspect a release valve or expansion tank
leak?

It's to big a job for me but it will save me ripping up carpets and
boards...!

You could try pressurising your CH system with your filling loop, and see
if
the
pressure release valve blows at 3 bars ( don't go much above that
whatever
happens ).

You could then try buying a new pressure relief valve as its very likley
that doing what you suggest will result in system dirt lodging under the
seat of the valve causing a slow drip which may not be curable:-(.
Never deliberately over pressure a relief valve on a system whuch has been
in use for any length of time.

I would suggest you fit a polythene freezer bag over the outlet pipe of
the relief valve with an elastic band to secure it. Then see if it
collects water in it when your boiler heats up. This will tell you if the
water is going out of the relief valve. Watch the pressure gauge after you
have charged the system while cold and switched it on to heat up the
radiators. An excessive pressure rise will indicate a lack of somewhere
for the water to expand into as the temperature rises. This means your
expansion vessel may have lost its gas precharge, it may have a blocked
connector pipe between vessel and system or it may never have been big
enough in the first place (more or less in that order)

On Thu, 31 Mar 2005 11:14:44 +0000, Simmmy wrote:

I have looked outside at the outlet pipe and it suggests it has been
leaking....water round the pipe and also on the ground underneath.

Whats the course of action now?

"I would suggest you fit a polythene freezer bag over the outlet pipe of the
relief valve with an elastic band to secure it. Then see if it collects
water in it when your boiler heats up. This will tell you if the water is
going out of the relief valve".

I would'nt say there was a excessive rise in water pressure whilst the
heating is running....just a loss of pressure after it cools back
down...again i can find no leaks to any plaster work inside the house or at
any radiators and boiler.

Sounds like the pressure relief valve has gone weak. This will need
replacing. The boiler manual will tell you how, if your are competent to
do so.

--
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

Thanks...really appreciate all the help.

Simmmy
"Ed Sirett" wrote in message
news
On Thu, 31 Mar 2005 11:14:44 +0000, Simmmy wrote:

I have looked outside at the outlet pipe and it suggests it has been
leaking....water round the pipe and also on the ground underneath.

Whats the course of action now?

"I would suggest you fit a polythene freezer bag over the outlet pipe of
the
relief valve with an elastic band to secure it. Then see if it collects
water in it when your boiler heats up. This will tell you if the water is
going out of the relief valve".

I would'nt say there was a excessive rise in water pressure whilst the
heating is running....just a loss of pressure after it cools back
down...again i can find no leaks to any plaster work inside the house or
at
any radiators and boiler.

Sounds like the pressure relief valve has gone weak. This will need
replacing. The boiler manual will tell you how, if your are competent to
do so.

--
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