Low Gas Pressure
Private Enquirer
to test exactly what was happening before deciding whether to call a CORGI
engineer or Transco/British Gas as I do not want to get fobbed off by either
as I like to understand what is happening first.
We had a new condensing boiler fitted about 4 years ago by British Gas - a
large one badged by BG but probably a
Worcester Bosch 40 HE Plus with a slightly higher heat output spec. They
upgraded the gas supply pipes to 28mm from the meter to allow for pressure
drops while running. Our gas cooker T's off this somewhere in 15mm I
believe. All working fine!
Two years ago we had a new gas meter and regulator/governor fitted as part
of the gas mains upgrade in our road in plastic.
Last week during very cold weather I measured 22mBar static pressure using a
conventional water gauge at the gas meter test point. When
the boiler fires up the working pressure drops to anything between 16mBar
and 18mBar still at the gas meter depending on how large a flame is being
demanded
by the central heating system. I therefore detect about 5mb drop just at
the meter.
I called British gas this week when the temperature was very much warmer and
they came
within the hour. He showed me his water gauge readings (all at the gas
meter as before)
and they were totally different from mine last week. The static pressure
was 24mb and the
working pressure was 19mb when the boiler was running full.
He got the same sought of drop in pressure I had found (i.e about 5mb drop)
but from a much
higher static pressure.
He seemed a bit officious and said mine was his third similar visit that day
and he blamed CORGI engineers for taking wrong readings. He thought my
governor was the best brand new type available and should be correct. He
said if the working pressure was below 19mb he could adjust the governor (I
thought they were not supposed to do that).
After he had gone I re-tested it myself and got very similar readings. I
found the static pressure was even up to 25mb today and I confirmed his
19mb working pressure.
I think we were both right on the different days as I had measured it low
last week when the only thing that had changed was the ambient temperature
which was much colder then. Does the gas pressure change much with
weather temperature and overall demand in the street?
I cannot get them to do anything today so am stuck with what I have got
for the time being. Everything seems to be working OK.
What do others think.
Andrew Mawson
"Private Enquirer" <pri...@NOSPAM.cwcom.net> wrote in message
news:rLmdnbhh2b-pLfDU...@bt.com...
I had a similar problem just before Christmas two years ago. Pavement
works dragged out my steel gas main. Transco insisted on pulling a
plastic pipe up the old one then wouldn't reconnect my appliances as
the pressure drop was too high. They went through three cycles of
pulling a bigger plastic pipe though before concluding I needed a
bigger meter (BGas had checked the boiler every year for ten years
with no issues!!) Wanted me to pay for a bigger meter. Eventually
resolved when I dragged the Transco big cheese out of a meeting in
Paris to give him a bollocking (hehe). However I'm personally
convinced that the problem was relatively low pressure in the street
main due to high demand and there was no problem with either the pipe
of meter.
AWEM
cynic
Ye canna change the laws of physics captain
Under exceptionally heavy loads such as everyone running boilers
simulataneously the dynamic pressure in the gas mains will reduce due
to pipe friction losses.
This is not helped at all by multiple large instantaneous demands from
high flow rate combis when hot water is called for (hot water storage
systems are much more forgiving)
It comes down to the gas distribution infrastructure. If this is a
regular thing then there is an argument for Transco to rip up the
roads, replace the pipes with larger etc etc. Of course Vladimir Putin
may also come into the equation!
Private Enquirer
"cynic" <icel...@talktalk.net> wrote in message
> Ye canna change the laws of physics captain ...
That (and the other poster) is the best answer I have had so far. BG may
have official published specs agreed with CORGI but it is clear that I am
seeing problems with their distribution. On the cold day with big demand my
governor had not actually cut in to do its job and all I was seeing was
direct pressure fluctuations in my newly plastic lined old iron pipe. They
re-laid the gas big street main using a push in plastic liner which is
obviously smaller than the original iron pipe. I should have called BG out
on a cold day to get a more realistic reading. The evidence was lost on a
warm day and everything appeared to me normal, although I suspect I should
not see a 5mb drop at the meter if the actual street supply is up to spec.
Thanks for that explanation
RW
If it ain't broke why try to fix it?
Does everything work as normal ?
if so why worry .
Ed Sirett
No. You need to see the difference between the running pressure when the
smallest hob ring is on it's lowest setting. The standing pressure (24mb)
just tells you that there is at least 24mb in the service main.
>
> He seemed a bit officious and said mine was his third similar visit that
> day and he blamed CORGI engineers for taking wrong readings. He thought
> my governor was the best brand new type available and should be correct.
> He said if the working pressure was below 19mb he could adjust the
> governor (I thought they were not supposed to do that).
No. You and I are not supposed to tamper with that but he may.
>
> After he had gone I re-tested it myself and got very similar readings.
> I found the static pressure was even up to 25mb today and I confirmed
> his 19mb working pressure.
>
> I think we were both right on the different days as I had measured it
> low last week when the only thing that had changed was the ambient
> temperature which was much colder then. Does the gas pressure change
> much with weather temperature and overall demand in the street?
Quite probably, not all areas, not even most will have a problem. It's
far worse in Bulgaria ;-)
>
> I cannot get them to do anything today so am stuck with what I have got
> for the time being. Everything seems to be working OK.
>
> What do others think.
What's happening at the hob. Can you see the flames alter? Do any of the
rings go out when on minimum?
--
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
Andrew Gabriel
Ed Sirett <e...@makewrite.demon.co.uk> writes:
>
> Quite probably, not all areas, not even most will have a problem. It's
> far worse in Bulgaria ;-)
I bet they don't bother to purge the the whole network
and everyone's home pipework before allowing it back on;-)
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Ed Sirett
> In article <rxtbl.67555$626....@newsfe09.ams2>,
> Ed Sirett <e...@makewrite.demon.co.uk> writes:
>>
>> Quite probably, not all areas, not even most will have a problem. It's
>> far worse in Bulgaria ;-)
>
> I bet they don't bother to purge the the whole network and everyone's
> home pipework before allowing it back on;-)
Never having being to Bulgaria I don't know what type of equipment is
commonly used. It might well be industrial type kit and communal heating.
ARWadsworth
"Ed Sirett" <e...@makewrite.demon.co.uk> wrote in message
news:tb4cl.10105$Rn6....@newsfe22.ams2...
> On Wed, 14 Jan 2009 23:26:39 +0000, Andrew Gabriel wrote:
>
> > In article <rxtbl.67555$626....@newsfe09.ams2>,
> > Ed Sirett <e...@makewrite.demon.co.uk> writes:
> >>
> >> Quite probably, not all areas, not even most will have a problem. It's
> >> far worse in Bulgaria ;-)
> >
> > I bet they don't bother to purge the the whole network and everyone's
> > home pipework before allowing it back on;-)
>
> Never having being to Bulgaria I don't know what type of equipment is
> commonly used. It might well be industrial type kit and communal heating.
>
Sorry for the late question, I have been away for a few days, but what would
happen in this country if a sizeable area actually lost its gas supply and
needed to be reconnected?
In my house the combi should be fine. The sensor will detect no gas and
close the valve off. I am sure my cooker would fill the house up with gas if
it lost its gas supply and then was reconnected. The closest scenario I can
find is when a gas main got filled with water in a nearby village (about 10
years ago) and each house on the supply had to be checked at the meter. That
was over 200 houses and it took a few weeks before everyone was back to
normal. I believe that every house had to be disconnected at the meter and
connected back up one by one.
Adam
Dave Liquorice
> Sorry for the late question, I have been away for a few days, but what
> would happen in this country if a sizeable area actually lost its gas
> supply and needed to be reconnected?
Reading between the lines of the reports relating to the big gas main fire
at Rawtenstall just before Christmas. They tell people to turn their gas
off at the meter. They then pressurise the main again, presumably purging
and checking for leaks as they say not turning off at the meter may slow
down return of supply. After that they visit every property and check it,
making sure pilot lights are lit etc.
A lot of ex-soviet Eastern Eurpean countries have massive communal heating
systems, not just individual buildings but whole blocks and towns.
--
Cheers
Dave.
Tim Downie
>
> Sorry for the late question, I have been away for a few days, but
> what would happen in this country if a sizeable area actually lost
> its gas supply and needed to be reconnected?
>
> In my house the combi should be fine. The sensor will detect no gas
> and close the valve off. I am sure my cooker would fill the house up
> with gas if it lost its gas supply and then was reconnected.
That happened with us recently when a gas main was accidentally cut. Before
the supply could be restored, every house ahd to have its gas supply turned
off. Fine if you were in the house when they called. If not, they dug up
your incoming supply and physically cut it off.
Tim
Ed Sirett
If someone chops through a service main with a JCB, it's much cheaper to
let the gas vent and monitor the pressure than to cut the gas off.
ARWadsworth
"Dave Liquorice" <allsortsn...@howhill.com> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.net...
I have had the pleasure of visiting some ex-soviet Eastern European
countries. The "modern" tower blocks which could mean anything from 1970
onwards may well have the communal heating systems. Believe it or not there
are systems in place that are quite similar in Doncaster. I was gobsmacked
when I saw it.
Adam
The Natural Philosopher
Martin Bonner
> On Mon, 19 Jan 2009 10:55:11 +0000, Tim Downie wrote:
> > ARWadsworth wrote:
>
> >> Sorry for the late question, I have been away for a few days, but what
> >> would happen in this country if a sizeable area actually lost its gas
> >> supply and needed to be reconnected?
>
> >> In my house the combi should be fine. The sensor will detect no gas and
> >> close the valve off. I am sure my cooker would fill the house up with
> >> gas if it lost its gas supply and then was reconnected.
>
> > That happened with us recently when a gas main was accidentally cut.
> > Before the supply could be restored, every house ahd to have its gas
> > supply turned off. Fine if you were in the house when they called. If
> > not, they dug up your incoming supply and physically cut it off.
>
> > Tim
>
> If someone chops through a service main with a JCB, it's much cheaper to
> let the gas vent and monitor the pressure than to cut the gas off.
But you probably want to discourage people from welding the pipe back
together again :-)