On Mon, 24 May 2004 19:22:24 +0000, Seri wrote:
"Ed Sirett" wrote in message
news
| On Mon, 24 May 2004 14:31:51 +0000, Seri wrote:
|
|
| "Ed Sirett" wrote in message
| news
| | "Seri" wrote
| | I have a new boiler snip I thought it was a great excuse to
purchase a
| | flammable gas detector snip I tested the existing gas piping
snip,
| one of the joins in the existing pipework manages
| | to just get the detector to tick over to the first level (above
| | 100ppm but less an 1000ppm),
| | What is the allowed maximum PPM of flammable gas from a join?
| |
| | Have a look in the Gas Fitting FAQ below.
| | The limit for Domestic Natural gas pipework is NO drop of pressure in
| | 2minutes when measured with a U-gauge and less than 0.25mBar when
measured
| | electronically.
|
| I read through the FAQ in its entirity, snip I can't easily perform a
'pipes only test'.
snip
| I know the FAQ says up to 4mBar drop over 2 minutes is allowed, but I
wanted
| to triple check.
| I have 1mBar drop (1.2 if being pedantic) testing at the meter test
point
| over the space of 2 minutes, this is with the cooker and boiler
connected to
| the pipework but in an 'off' state, is this a natural and allowable
drop?
|
| It would be best at this point to turn the cooker and boiler off at their
| respective isolators or remove the bayonet hose. The boiler will likely
| have some sort of 1/4 turn cut off.
| If you then get a 0 drop (you did allow a 1 min settling time before
| beggining the test?) AND there is no smell of gas then that is adequate.
|
| If you still get a non zero drop then the leak MUST be found.
| It could be anywhere from the MCV, meter, govenor or pipe work.
|
|
| Likely placed where it is good to start looking:
| 1) any place where the pipe comes out of a concrete floor.
| 2) anywhere the pipe goes unprotected through a wall.
| 3) around the meter especially if it has been changed recently.
| 4) New pipe work.
| 5) The anaconda (flexible corrugated stainless pipe) especially if it had
| flux on it and/or got wet.
|
| A pro will probably
| 1) test the U guage for leaks (to eliminate the wild goose chase).
| 2) Put a disc in the meter outlet to split the problem between the meter
| and your pipes.
|
| Appliances are allowed to leak slightly provided they don't smell.
| Pipes are never allowed to leak, any.
Thanks for the continued help, unfortunately the previous owner of this
property (well, his dad) installed everything himself and had 'interesting'
ideas about the way things should have been done, this has ranged from the
water plumbing to the electrics to the extension to the gas fittings, the
entire thing.
I can't locate any easy way of isolating either the hob or the central
heating boiler, the upstairs water on demand boiler has a master gas 'off'
valve which I turned off before starting any testing but the same doesn't
seem to be possible for the other two devices.
I left the gauge to settle for a minute before starting testing, but as
said, the hob and the heating boiler were off but not isolated from the gas
supply.
I also ensured that the testing screw was tested with gas leak detection
fluid and the new electronic gas detector before turning on the gas supply.
Basically, my question now is this, from what's been said so far, the gas
here needs some extensive testing.
I've been in this property with the current state of affairs for just over
two years.
All of the 15mm gas pipe will need to be replaced with 22mm pipe to
accomodate the new boiler (this would take it almost all the way back to the
meter)
The hob is fed from an entirely seperate feed from the meter.
The replacement pipework and the installation of the boiler will be
happening in about 4 weeks.
Q: Should this be okay as it is until the new boiler is installed?
Q: With no device other than the hob connected is it normal that I'll notice
any drop? (I seem to recall hobs can be a little 'lossy')
IME appliances rarely leak, leaks are usually the pipework.
Well if you were registered and you found a leaking installation you need
to do one of two things:
a) Fix it.
b) Turn it off and label it as dangerous.
Anything else is not competant gas fitting so you are invited to make you
own assessment.
--
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