Why size of gas pipe?

[peteheat]

Thanks for all the sensible answers lol.

BTW some years ago a qualified plumber/gas fitter put in a replacement high level toliet cistern in my Dad's house.

He then found the overflow outlet was on the wrong side, so could not go directly out of the wall like the previous pipe.

So he did some very neat pipework out of the other side of the cistern, upwards to clear the top of the tank, horizontally along the top of the tank, back down the other side then horizontally out through the original hole in the wall.

I spotted this wonderful plumbing when I was standing there one day using the facilities.

What prize shall I give for anyone who can spot what was wrong?

PS I feel it is a good job I didn't ask why he didn't do the whole gas pipe run in flexi to make the job even easier!

Actually he could have, you mighrt not have liked the cost though, love the cistern story, just shows how valuable a drill is

 

[Howsie]

Thanks for all the sensible answers lol.

BTW some years ago a qualified plumber/gas fitter put in a replacement high level toliet cistern in my Dad's house.

He then found the overflow outlet was on the wrong side, so could not go directly out of the wall like the previous pipe.

So he did some very neat pipework out of the other side of the cistern, upwards to clear the top of the tank, horizontally along the top of the tank, back down the other side then horizontally out through the original hole in the wall.

I spotted this wonderful plumbing when I was standing there one day using the facilities.

What prize shall I give for anyone who can spot what was wrong?

PS I feel it is a good job I didn't ask why he didn't do the whole gas pipe run in flexi to make the job even easier!

Doesn't sound like any qualified plumber I know. Are you sure he was qualified?

 

[stratobuddy]

Yes, but a long time ago, before even Corgi.

He was excellent on lead piping and wiped joints.

 

[kay-jay]

Yes, but a long time ago, before even Corgi.

He was excellent on lead piping and wiped joints.

Before even common sense?

Sent from my GT-I9100 using Tapatalk 2

 

[Roger Welton]

Before even common sense?

I believe it is still optional now

 

[snowhead]

I believe it is still optional now

Health and Safety legislation has ruled out the need for anyone to have common sense.

 

[frankjames]

You Must ! do a complete run from the gas meter in 22mm and the the final foot or so in 15mm.

 

[AWheating]

You Must ! do a complete run from the gas meter in 22mm and the the final foot or so in 15mm.

are you a gas safe registered engineer? how did you work out the pipesize?

 

[Koogatubac]

Think hes going off a general rule, however thats kind of changed now combi's are getting higher KW and if they have other appliances.

General rule now in domestic normal 3 bed semis are 28mm off meter, main run of 22mm then boilers are normally 15mm connections so i normally just reduce at last elbow to boiler.

Every situation is different though! Thats where your experience and knowledge comes into play

 

[Dotty]

And 20 minutes sitting down to size it properly. Don't take long. Do it right the first time!

 

[neily01]

are you a gas safe registered engineer? how did you work out the pipesize?

i have a nice little work sheet the gas center made up. i dont know if you boys use the same method but the initial calculation is appliance kw x .09 = required meters per hour. i find this is always slighty undersized compared to m/i

 

[DirksPlumbing]

Those installers fitting incredible lengths of 15mm for LPG do my head in.
But at least thanks to modulating boilers its only NCS.

Then again if you gas rate a zero governor boiler on NG with 13mbar inlet you will be amazed to find it running at full capacity. Just the oven needs a bit longer in winter to warm up.
And your FGA might be a bit off.

Now my question why have domestic boilers from 35kW a 22mm gas connection and not 28mm?

 

[Dotty]

Because it's what the manufacturer decides. They probably want to standardise as much as they can for buying in bulk thereby reducing their outlay and increasing their profit margins. As you know, it's down to you as the gsr to ensure the pipe's properly sized.

 

[stratobuddy]

Another installer I was involved with had a "suck it and see" approach.

Pipe from meter was 22mm and disappeared below floor. When it came back up again on the opposite side of the house at the old boiler it was 15mm.

There was no way of finding out how far away it changed to 15mm. It could have been 1 metre away, or the whole depth of the house.

So GSR installed new combi boiler using the existing pipe, then fired it up and made various gas measurements at the boiler.

He said these were OK, so there was no need to run new pipework across the house.

 

[neily01]

Those installers fitting incredible lengths of 15mm for LPG do my head in.
But at least thanks to modulating boilers its only NCS.

Then again if you gas rate a zero governor boiler on NG with 13mbar inlet you will be amazed to find it running at full capacity. Just the oven needs a bit longer in winter to warm up.
And your FGA might be a bit off.

Now my question why have domestic boilers from 35kW a 22mm gas connection and not 28mm?

fitted a vaillant for the first time in a while, o/vent model. nice little chart inside giving you meter op to boiler ip. 19mb op means you can have as little as 15mb ip, allowing for a aprox 1.5mb across gas valve means their happy with 16.5 mb at appliance. just as a side note now started installing test nipples just before the appliance, know my pipe sizing is correct then.

 

[AWheating]

Now my question why have domestic boilers from 35kW a 22mm gas connection and not 28mm?

fitted a 38kw heat only recently with a 15mm connection. The boilers connection size has no relavance to pipework/carcus apart from the last connection of course.

 

[Mike Jackson]

Another installer I was involved with had a "suck it and see" approach.

Pipe from meter was 22mm and disappeared below floor. When it came back up again on the opposite side of the house at the old boiler it was 15mm.

There was no way of finding out how far away it changed to 15mm. It could have been 1 metre away, or the whole depth of the house.

So GSR installed new combi boiler using the existing pipe, then fired it up and made various gas measurements at the boiler.

He said these were OK, so there was no need to run new pipework across the house.

Nothing wrong with that approach. If I can't see a lot of the run I will quote to fit a boiler on the existing pipe run with an extra cost to upgrade the gas pipe if necessary. If the gas supply is insufficient the customer is prepared for the extra cost and if it's fine they've saved paying me for unnecessary work.

 

[stratobuddy]

That's what I thought too.

A new supply would be difficult, parts of it would have to be outside the house on an external wall, a temptation to copper thieves.

 

[Anton]

What are the chances of all 4 qualified gas engineers being wrong?

The same odds as Wayne Rooney having more than one brain cell.

 

[peteheat]

The same odds as Wayne Rooney having more than one brain cell.

Ahhh chit, ye mean Wayne Rooney is GSR now as well?

Too many believe the rumors about plumbers earnings