"Brett Jackson" wrote in message
...
I have a Vokera Linea 28 boiler which intermittently fails to ignite. The
light on the front flashes red and I get an error number. The strange
thing
is that it is only when the weather is colder, and only usually between
5pm
to 7pm. It might do this four or five times per year between Sept and
March.

I'm led to thinking that this may be a localised gas pressure issue (5-7pm
people will have their hobs/ovens on, and their CH systems will be getting
the house warm for the evening), or maybe something to do with the gas
pipe.

Question is, should I be concerned about this and seek a resolution, or
just
resign to re-setting the boiler now and again?





Why don't you get a u-tube manometer ( or make one ) and see if your theory
is correct? You caould measure at the bleed nipple on your gas meter, or at
an approprate point on your boiler ( see manual ), if you feel you are
competent. It may require a bit of patience, but if it turns out to be a
drop in the gas pressure, you could examine the gas pipe run from your meter
to your combi and see if it could be beefed up. IIRC, it should be 22mm pipe
to within a metre of the combi, and even then I suppose it depends on the
power output of the combi ( though 28kW should be OK for
22mm pipe generally ). How long is your gas run? How many elbow joints are
there?

Andy.

Combi boiler potential problem
 

I have a Vokera Linea 28 boiler which intermittently fails to ignite. The
light on the front flashes red and I get an error number. The strange thing
is that it is only when the weather is colder, and only usually between 5pm
to 7pm. It might do this four or five times per year between Sept and
March.

I'm led to thinking that this may be a localised gas pressure issue (5-7pm
people will have their hobs/ovens on, and their CH systems will be getting
the house warm for the evening), or maybe something to do with the gas pipe.

Question is, should I be concerned about this and seek a resolution, or just
resign to re-setting the boiler now and again?

"andrewpreece" wrote in message
...

"Brett Jackson" wrote in message
...
I have a Vokera Linea 28 boiler which intermittently fails to ignite.
The
light on the front flashes red and I get an error number. The strange
thing
is that it is only when the weather is colder, and only usually between
5pm
to 7pm. It might do this four or five times per year between Sept and
March.

I'm led to thinking that this may be a localised gas pressure issue
(5-7pm
people will have their hobs/ovens on, and their CH systems will be
getting
the house warm for the evening), or maybe something to do with the gas
pipe.

Question is, should I be concerned about this and seek a resolution, or
just
resign to re-setting the boiler now and again?





Why don't you get a u-tube manometer ( or make one ) and see if your
theory
is correct? You caould measure at the bleed nipple on your gas meter, or
at
an approprate point on your boiler ( see manual ), if you feel you are
competent. It may require a bit of patience, but if it turns out to be a
drop in the gas pressure, you could examine the gas pipe run from your
meter
to your combi and see if it could be beefed up. IIRC, it should be 22mm
pipe
to within a metre of the combi, and even then I suppose it depends on the
power output of the combi ( though 28kW should be OK for
22mm pipe generally ). How long is your gas run? How many elbow joints are
there?

Andy.



I wouldn't know where to start with a manometer. I've done my own CH and
replaced all the plumbing in the house but I'm not so keen to do anything
with the gas.

The 22mm pipe runs to within 2m of the boiler where it drops to 15mm. There
are 4 elbow joints and 2 90 degree bends in to 22mm pipe and 2 elbows + 1
bend in the 15mm pipe. Overall the length of pipe from the meter to the
boiler is 11m all-in. The only other thing using the gas is the hob which
is connected to the same 22mm run right next to the meter.

I wouldn't have though the pipe size would effect the ability for the boiler
to fire in the first place?

"Brett Jackson" wrote in message
...

"andrewpreece" wrote in message
...

"Brett Jackson" wrote in message
...
I have a Vokera Linea 28 boiler which intermittently fails to ignite.
The
light on the front flashes red and I get an error number. The strange
thing
is that it is only when the weather is colder, and only usually
between
5pm
to 7pm. It might do this four or five times per year between Sept and
March.

I'm led to thinking that this may be a localised gas pressure issue
(5-7pm
people will have their hobs/ovens on, and their CH systems will be
getting
the house warm for the evening), or maybe something to do with the gas
pipe.

Question is, should I be concerned about this and seek a resolution,
or
just
resign to re-setting the boiler now and again?





Why don't you get a u-tube manometer ( or make one ) and see if your
theory
is correct? You caould measure at the bleed nipple on your gas meter, or
at
an approprate point on your boiler ( see manual ), if you feel you are
competent. It may require a bit of patience, but if it turns out to be a
drop in the gas pressure, you could examine the gas pipe run from your
meter
to your combi and see if it could be beefed up. IIRC, it should be 22mm
pipe
to within a metre of the combi, and even then I suppose it depends on
the
power output of the combi ( though 28kW should be OK for
22mm pipe generally ). How long is your gas run? How many elbow joints
are
there?

Andy.



I wouldn't know where to start with a manometer. I've done my own CH and
replaced all the plumbing in the house but I'm not so keen to do anything
with the gas.

The 22mm pipe runs to within 2m of the boiler where it drops to 15mm.
There
are 4 elbow joints and 2 90 degree bends in to 22mm pipe and 2 elbows + 1
bend in the 15mm pipe. Overall the length of pipe from the meter to the
boiler is 11m all-in. The only other thing using the gas is the hob which
is connected to the same 22mm run right next to the meter.

I wouldn't have though the pipe size would effect the ability for the
boiler
to fire in the first place?

I would imagine a manometer is the only way to confirm your theory about the
gas pressure dropping. It's just a u-tube of clear plastic tubing, about a
foot fro tp to bottom, half-filled with water. Stuff one end of the pipe on
the gas nipple/whatever to be measured, crack open the gas nipple or turn on
the gas, and watch the water o down on one side of the tube, and rise up on
the other. The gas pressure, in millibars, is the difference in height
between the two columns of water, measure in centimetres. The pressure
should be about 18-20 millibars I think. You could take a reading earlier in
the day then watch how the water levels vary between 5 and 7pm, and see if
they fall unusually low...be careful about gas leaks though.

Andy.

On Sun, 19 Sep 2004 17:23:53 +0100, Brett Jackson wrote:


"andrewpreece" wrote in message
...

"Brett Jackson" wrote in message
...
I have a Vokera Linea 28 boiler which intermittently fails to ignite.
The
light on the front flashes red and I get an error number. The strange
thing
is that it is only when the weather is colder, and only usually between
5pm
to 7pm. It might do this four or five times per year between Sept and
March.

I'm led to thinking that this may be a localised gas pressure issue
(5-7pm
people will have their hobs/ovens on, and their CH systems will be
getting
the house warm for the evening), or maybe something to do with the gas
pipe.

Question is, should I be concerned about this and seek a resolution, or
just
resign to re-setting the boiler now and again?





Why don't you get a u-tube manometer ( or make one ) and see if your
theory
is correct? You caould measure at the bleed nipple on your gas meter, or
at
an approprate point on your boiler ( see manual ), if you feel you are
competent. It may require a bit of patience, but if it turns out to be a
drop in the gas pressure, you could examine the gas pipe run from your
meter
to your combi and see if it could be beefed up. IIRC, it should be 22mm
pipe
to within a metre of the combi, and even then I suppose it depends on the
power output of the combi ( though 28kW should be OK for
22mm pipe generally ). How long is your gas run? How many elbow joints are
there?

Andy.



I wouldn't know where to start with a manometer. I've done my own CH and
replaced all the plumbing in the house but I'm not so keen to do anything
with the gas.

The 22mm pipe runs to within 2m of the boiler where it drops to 15mm. There
are 4 elbow joints and 2 90 degree bends in to 22mm pipe and 2 elbows + 1
bend in the 15mm pipe. Overall the length of pipe from the meter to the
boiler is 11m all-in. The only other thing using the gas is the hob which
is connected to the same 22mm run right next to the meter.

I wouldn't have though the pipe size would effect the ability for the boiler
to fire in the first place?

You have nailed down the circumstances so preciusly that I think it is
almost certain that a gas supply pressure problem is involved.

Whilst Transco try to get everyone to have at least 21mBar +/- 1mb meter
outlet pressure at all times I beleive they are legally obligated to
provide 15mBar. This means all gas appliances are expected to work safely
(if not effectively) with a supply proessure of 14mBar.

You might have somewhat poor pipework (house with totally compliant pipe
work are few and far between) that's loosing say 3 mBar and the boiler is
having difficulty.

You can either wait a few years to see if Transco dig up the road and give
you a more constant supply, or you can have the gas pipe work brought up
to scratch.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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