[Nick]

I have had this problem for about a year now. The original post he
http://groups.google.co.uk/group/uk....pr%40yahoo.com

Its a 12 year old Worcester combi boiler. When we use the hot water,
it works ok for about 5 mins and then the pilot goes out hence the
flames go out. We have to wait a couple of mins and then re-light the
pilot after a few attempts. The hot water will then work for about 3
mins and then same happens again and so on. The central heating works
fine and will carry on all night if necessary.

Originally we called out Britisg Gas (BG) as we have homecare. They
had no idea what was wrong. I then complained and had 2 more visits.
They could not fnd anything and just made up an execuse that my
central heating was blocked up and needed a flush etc. otherwise they
would not look at my boiler anymore. We had Transco check out gas
pressure and they said everything was ok.

Come April/May and I was really fed of not being able to have proper
running water so decided to replace the boiler. All of a sudden the
problem went away. So we put the new boiler plan on the 'back-burner'
and carried on with the old boiler through the summer months. Then
towards end of Sept it started again and then got progressively worse.
This weekend it went out and would not light up at all again. Note
that this weekend is the coldest of the year so far.

I am no engineer but this points something to do with gas usage or
pressure. First its nothing to do with CH blockage as CH works fine,
its only hot water that triggers the pilot. Secondly the boiler worked
fine during the summer months. Now that it is really cold it is worse.
Could there be some issues with gas pressure?

I am going to cancel BG homecare because they have been useless. How
do I get Transco to give me true facts? I am loathed to spend 2k on a
new boiler installation just because there may be something wrong with
the gas supply.

All ideas welcome.

[Newshound]

When you run the DHW with the CH off, does the boiler seem to get noisier
before it cuts out? This is the symptom with mine (no pilot light, and it
cuts out sooner than 5 minutes), but it is cutting out on primary water
over-temperature (hence sounds of incipient boiling) because not enough heat
is getting transferred to the DHW through the partially blocked heat
exchanger. Are you in a hard water area? In my experience, 12 years is a
pretty good life for a modern combi.

Ed will probably be along in a minute!

[[email protected]]

On Sun, 23 Nov 2008 04:26:09 -0800 (PST), Nick
wrote:

I have had this problem for about a year now. The original post he
http://groups.google.co.uk/group/uk....pr%40yahoo.com

Its a 12 year old Worcester combi boiler. When we use the hot water,
it works ok for about 5 mins and then the pilot goes out hence the
flames go out. We have to wait a couple of mins and then re-light the
pilot after a few attempts. The hot water will then work for about 3
mins and then same happens again and so on. The central heating works
fine and will carry on all night if necessary.

Originally we called out Britisg Gas (BG) as we have homecare. They
had no idea what was wrong. I then complained and had 2 more visits.
They could not fnd anything and just made up an execuse that my
central heating was blocked up and needed a flush etc. otherwise they
would not look at my boiler anymore. We had Transco check out gas
pressure and they said everything was ok.

Come April/May and I was really fed of not being able to have proper
running water so decided to replace the boiler. All of a sudden the
problem went away. So we put the new boiler plan on the 'back-burner'
and carried on with the old boiler through the summer months. Then
towards end of Sept it started again and then got progressively worse.
This weekend it went out and would not light up at all again. Note
that this weekend is the coldest of the year so far.

I am no engineer but this points something to do with gas usage or
pressure. First its nothing to do with CH blockage as CH works fine,
its only hot water that triggers the pilot. Secondly the boiler worked
fine during the summer months. Now that it is really cold it is worse.
Could there be some issues with gas pressure?

I am going to cancel BG homecare because they have been useless. How
do I get Transco to give me true facts? I am loathed to spend 2k on a
new boiler installation just because there may be something wrong with
the gas supply.

All ideas welcome.

Could the thermocouple need replacing .Cheaper than a boiler to see if
it is that.

[Dave Liquorice[_2_]]

On Sun, 23 Nov 2008 04:26:09 -0800 (PST), Nick wrote:

When we use the hot water, it works ok for about 5 mins and then the
pilot goes out hence the flames go out. We have to wait a couple of mins
and then re-light the pilot after a few attempts. The hot water will
then work for about 3 mins and then same happens again and so on. The
central heating works fine and will carry on all night if necessary.

I'd be tempted to replace the thermocouple and check the size and position
of the pilot light flame. Though the fact that it works fine for CH is
counter to a duff thermocouple or badly adjusted pilot flame. Does the CH
use a different burner or different parts of the same burner compared to
HW?

Note what another posted has said about more noise in HW mode just before
it stops. It could be the overheat trip doing what it should due to the HW
heat exchanger being scaled up.

--
Cheers
Dave.

[YAPH]

On Sun, 23 Nov 2008 12:34:33 +0000, newshound wrote:

When you run the DHW with the CH off, does the boiler seem to get noisier
before it cuts out? This is the symptom with mine (no pilot light, and it
cuts out sooner than 5 minutes), but it is cutting out on primary water
over-temperature (hence sounds of incipient boiling) because not enough heat
is getting transferred to the DHW through the partially blocked heat
exchanger. Are you in a hard water area? In my experience, 12 years is a
pretty good life for a modern combi.

Good point. When you have to relight the boiler is there a reset button
somewhere you have to press back in before it will relight? Does the
thermocouple have either a couple of tags partway along its length, or
where it's connected to the gas valve are there a couple of wires going
off to an overheat trip switch?

If you can feel the flow pipe from the heat exchanger (inside the boiler,
not the one coming out of the boiler to the CH - and take care you don't
touch anything electrical while doing this) does it get much hotter on DHW
than on CH? (An infra-red thermometer or some sort of thermometer you can
get onto this pipe would tell you more accurately).

--
John Stumbles -- http://yaph.co.uk

Seagull Management
Management technique characterised by flying in, making a lot of noise,
crapping on everything, and then leaving.

[Nick]

Yes it does get noisier with hot water but is very quite with CH. I
had the gas pressure checked out and its spot on; no problems there.

So could it be just the blocked up CH system as BG claim? If so why
didnt they address that in their annual maintenance programme or at
least tell me about flushing.

[Dave Liquorice[_2_]]

On Mon, 24 Nov 2008 00:35:55 -0800 (PST), Nick wrote:

So could it be just the blocked up CH system as BG claim?

Unless they are being very loose with their terminology I'd say the CH
system is fine and it's a scaled up heat exchanger for the HW.

If so why didnt they address that in their annual maintenance programme
or at least tell me about flushing.

Scaling of the heat exchanger is "wear and tear" TBH there is very little
to actually routinely maintain in a room sealed boiler. They just work
until a moving part wears out or scale builds up.

--
Cheers
Dave.

[Toby]

Nick wrote:
Yes it does get noisier with hot water but is very quite with CH. I
had the gas pressure checked out and its spot on; no problems there.

So could it be just the blocked up CH system as BG claim? If so why
didn't they address that in their annual maintenance programme or at
least tell me about flushing.

I am no expert, but if the CH works, and the DHW if the thing causing the
boiler to trip out, I can't see the problem being with the CH side!

It could be a scaled up heat exchanger on the DHW side, resulting in the
boiler calculating the flow rate and adjusting the burners to what it then
thinks is correct for that situation, but then not getting enough heat away
from the boiler, then the overheat trip triggers.

Do you live in a hard water area, if so, do you have anything to prevent
scale, like an ion exchange water softener?

Toby...

[Nick]

They have been and this time figured out that some part had gone it.
They returned next day with tha part (SW Stat??) - a little cumbell
type device with 2 long leads. They installed this part and the pilot
came back on and stayed on. They left.

However, the old problem still exists - when using hot water, it keeps
going out every 4-5 mins and the pilot has to be re-lighted.

Also they said that the bolier is on a reduced parts list - they cant
get all the parts for it. Its a Wrcester combi bought in 1996.