New boiler undergassed. Blame gas meter governor?

[ernie mendoza]

I have just had a new Worcester-Bosch 24i system boiler installed in
the loft to replace a 30-year-old non-condensing boiler in the
kitchen. Tests show it is "undergassed". The installer says it may
be a problem with the gas meter governor, in which case they say
Transco would have to fix it. However the 22mm pipe required by the
boiler is connected to a 15mm pipe from the gas meter. Should the
installer fit a larger pipe to the gas meter instead of blaming the
governor and shifting the problem to Transco? Any advice most
welcome.

[John]

"ernie mendoza" <scra...@nospam.com > wrote in message
news:fp6a265q91ip8uck6...@4ax.com...

I'm about to have a similar change with a 30CDi - into the loft. Pipe sizes
cannot be readily checked so I may have the same problems and will need an
external 22mm up to the loft.

Worcester will give good advice if you know the pressure at the boiler. I
had this:

"The recommended working gas pressure at the appliance is 18.0mbar however
the boiler will function correctly when set as low as 16.5mbar. In most
cases when testing the working gas pressure with other devices in the
property this 22mm pipe diameter is necessary. Should your installer be able
to achieve at least 16.5mbar on 15mm pipe-work then the manufacturers
warranty should remain unaffected. "

[John Rumm]

Easy enough to check. Just work out if the pipework you have is adequate
for the required flow rate.

Look in your boiler manual[1] for the maximum gas flow rate required by
the boiler in cubic metres per hour. Then use the pressure drop tables
shown here:

http://www.copperinfo.co.uk/plumbing-heating-and-sprinklers/downloads/pub-124-copper-for-domestic-gas-installations.pdf

To see if your pipework is adequate can deliver the required flow.

[1] Available here if you have not got it:

http://www.worcester-bosch.co.uk/installer/products/gas-boilers/greenstar-24i-system

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

[fred]

In article <iPudnRw-FaTgyLjR...@brightview.co.uk>, John
Rumm <see.my.s...@nowhere.null> writes

>On 25/06/2010 22:16, ernie mendoza wrote:
>
>> I have just had a new Worcester-Bosch 24i system boiler installed in
>> the loft to replace a 30-year-old non-condensing boiler in the
>> kitchen. Tests show it is "undergassed". The installer says it may
>> be a problem with the gas meter governor, in which case they say
>> Transco would have to fix it. However the 22mm pipe required by the
>> boiler is connected to a 15mm pipe from the gas meter. Should the
>> installer fit a larger pipe to the gas meter instead of blaming the
>> governor and shifting the problem to Transco? Any advice most
>> welcome.
>
>
>Easy enough to check. Just work out if the pipework you have is adequate
>for the required flow rate.
>
>Look in your boiler manual[1] for the maximum gas flow rate required by
>the boiler in cubic metres per hour. Then use the pressure drop tables
>shown here:
>
>http://www.copperinfo.co.uk/plumbing-heating-and-sprinklers/downloads/pub-
>124-copper-for-domestic-gas-installations.pdf
>
>To see if your pipework is adequate can deliver the required flow.
>
>
>[1] Available here if you have not got it:
>
>http://www.worcester-bosch.co.uk/installer/products/gas-boilers/greenstar-24i-
>system
>

In addition, if the installer is suggesting that the meter regulator is
faulty then invite him to measure the pressure at the meter outlet test
point with the o/p present and show that it is out of spec (20mbar
+/-1mbar) with the boiler running flat out. O/P may need to watch out
for smoke & mirrors at this point to avoid being duped by a dodgy
measurement technique.

Finger in the air suggests it should be 22mm to within 20cm of the
boiler but nothing beats the full design process above.

Good info here http://www.makewrite.demon.co.uk/GasFitting.html under:
3 Working on Gas Pipework
a) What size pipes should be used for gas?
--
fred
FIVE TV's superbright logo - not the DOG's, it's bollocks

[cynic]

Instead of simply blaming the governeor he should fit his manometer to
the test nipple on the meter and measure the pressure at the meter
with the appliances running. Unles you live in a bugalow with the
meter close below the boiler I would say the pipe is likely to require
uprating.
Transco will probably tell you the same thing

[ransley]

What did the old boiler consume, the new unit is smaller and uses less
gas, right. Was a Manometer used to test flow

[js.b1]

On Jun 25, 10:16 pm, ernie mendoza <scramb...@nospam.com > wrote:
> the 22mm pipe required by the boiler is
> connected to a 15mm pipe from the gas meter.

If the installers has fitted 15mm pipe from the gas meter, they have
fitted too small a pipe. Which begs the question, is the person Gas
Safe or sub-contracted from one who is?

[timothy...@gmail.com]

As a GasSafe engineer. I would not leave any appliance attached to any gas pipe if the input pressure did not meet that specified in the Manufacturers Installation Instructions. If there was a problem with the meter governor, I would ask the O/P to attend.

[No Name]

As I understand it, a competent GasSafe engineer should be doing
calculations on the pressure drop along the gas pipework taking into
account its length, diameter and gas "load for each appliance connected.

The idea is that when everything is running at full pelt, the prssure at
*any* point in the pipework is still +/- 1 mBar of 20 mBar

Where gas pressure is insufficient, the practical solution is to
actually increase the pipe diameter accordingly to bring the pressure
drop to within 1 mBar.

In my case, I have 28 mm pipe from the gas meter, This runs to the
landing floor where it then Tees off to two off 22mm pipe.

One feeds a 38 kW COmbi boiler and the other then feeds the cooker which
comprises of two gas ovens and a 5 ring hob. (one of the burners is a
Wok burner)

So expecting a combi boiler to run off at least 10m of 15 mm copper pipe
is unrealistic. Either uprate the pipe diameter or fit a smaller boiler
and then complain how the hot water is not hot enough or has poor flow rate!

[Fredxx]

On 13/07/2020 14:48:15, Chris Hogg wrote:

> I imagine Mr Mendoza has either had it fixed or blown himself to
> smithereens in the intervening ten years...

While you are correct, it is welcome to have someone this group who is
both versed in gas and helpful. Elsewhere these two characteristics seem
mutually exclusive.

[John Rumm]

Yup helpful is good, but I would kind of hope one quality you can count
on in a gas fitter is attention to detail :-)

And yes, for the OP, his 24kW boiler will have a gas rate of around 2.2
m^3/hour [1]. And a 15mm pipe will not be able to supply that gas rate
through 15mm pipe over an effective pipe length of much over 4m [2],
which makes it unlikely that it would be ins spec at the time of fitting.

[1]

http://wiki.diyfaq.org.uk/index.php/Gas_units

[2]

http://wiki.diyfaq.org.uk/index.php/Gas_pipe_sizing#Design_Data

[Cynic]

This thread was resurrected from 2010. What's gone on this time?

[Tim+]

Cynic <johnje...@gmail.com> wrote:
> This thread was resurrected from 2010. What's gone on this time?
>

I suspect other web portals are copying Home Owners Hub and are presenting
old messages as new. Can’t be arsed to check though. ;-)

Tim Packwood, maybe you could enlighten us?

Tim
--
Please don't feed the trolls

[Brian Gaff (Sofa)]

Well back in 2010, I imagine its probably blown up by now anyway.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
bri...@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
<timothy...@gmail.com> wrote in message
news:09e1871f-1cdc-4726...@googlegroups.com...