Gas Pipe Sizing Question

[cr0ft]

Gents,

I don't have my gas books to hand but went to a quote tonight. Amongst other things the customer wants a gas boiler service. She asked me to look at a gas pipe outside. Immediate thoughts were that it wasn't sleeved at all going through the cavity wall. It was installed by a local competitor in 2012.

The pipe is run in 22mm to the boiler and has 9 elbows and is 22m (ish) long. It's a 30KW combi boiler. I think the pipe is undersized and that I am going to run the part outside the house in 28mm up into the loft of the bungalow.

No other gas appliances in the house.

Can any kind soul do the calculation for me please? I wanted to do the quote tonight that's all.

Cheers

 

[Chalked]

Needs some 28 in there pretty much up to 3m of the appliance

 

[plumben]

Mr Combi app reckons 28mm giving a pressure drop of 0.530mbar

 

[Dotty]

Mr Combi app reckons 28mm giving a pressure drop of 0.530mbar

It's what I get.

 

[jtsplumbing]

Did you do any checks ? what were you getting at Boiler

 

[tamz]

Pressure drop on 22m of 22mm with 9 elbows would be in the region of 1.33mb.
Not right but hardly the end of the world.
Stick 6m or 9m of 28mm on and it will be below 1mb.

 

[REDSAW]

so its A.R then?

 

[tamz]

Naw its NCS and you don't need to do anything except not it down or inform them.

 

[REDSAW]

Naw its NCS and you don't need to do anything except not it down or inform them.

back on the books this week and its AR not sleeved. daft innit!

 

[tamz]

Not sleeved is classed as wgaf too

 

[jtsplumbing]

Not sleeved is classed as wgaf too

Wgaf = ???????????

 

[tamz]

Write it down, forget it and move on is the polite way of saying it.

Its a shame it took a judge to get gas safe and the hse to bring out GIUSP7 in the hope it will stop engineers scaring the **** out of people unnecessarily and focus on what the real dangers are.

 

[cr0ft]

It's what I get.

View attachment 25703

Going to get that app, looks very handy. Thanks all.

 

[cr0ft]

Write it down, forget it and move on is the polite way of saying it.

Its a shame it took a judge to get gas safe and the hse to bring out GIUSP7 in the hope it will stop engineers scaring the **** out of people unnecessarily and focus on what the real dangers are.

To my mind I was more concerned about the gas pipe going through a hole that looks like it's been drilled out with a 22mm masonry bit. The gas pipe was proper tight in there and any relative movement of the leafs of the cavity would likely damage it. It's also a proper mess around the outside of the house too, that's what the customer wasn't happy with and she wants it sorted out!

Will run it in 28mm from the meter box and through the loft, easy enough to do and it needs sleeving anyway so may as well do the job properly.

I haven't checked the pressure drop yet at the boiler as it was just a quote for various different jobs. Either way though if I am sorting out the sleeving then I may as well install it to the correct size anyway.

 

[tamz]

Thats fair enough. It should be sleeved and you were right to point it out and rectify it at the homeowners cost.
What i'm on about is more coming across it on a job where you are there for something else or a LLC and are in and out. Its a NCS, it won't kill anyone so you inform the people without scaring them into spending money they don't need to and move on.

 

[cr0ft]

Just noticed in the latest gas bulletin, NCS is being abolished anyway from July 2016 so would you now classify this as AR (no sleeving through wall) or let it go?

http://www.User PlumbersForums.net ...ituation_Procedure_(GIUSP)_Edition_7.0_v1.pdf

(Section 2 refers).

The question is: -

Does a situation exist on the appliance/installation which may lead to an unsafe situation. I would argue that in this case with the pipe tight against both cavity leafs it does. In this case there is almost no gap to allow movement. What do others think?

(Not going to AR the install, just interested in other people's thoughts on this now NCS are no more).

 

[Howsie]

From a pressure perspective, a lot will depend on the boiler as well.

 

[ShaunCorbs]

Ar as it is at risk of the cement eating through the copper and filling the void

 

[plumben]

I'd be with Shaun on this one, at risk of potentially rupturing the pipe from either corrosion or movement in one side of the wall causing the cavity to fill with gas that would potentially go un noticed

 

[tamz]

NCS is NOT being done away with, just the need to formally inform. Its a bit of a mess really .
You don't up the classification.
An unsleeved pipe is still not to current standards because it should have a sleeve however the risk is so small it is negligible and has now been removed from the GIUSP. You would just mark it down or verbally inform as pipe should be sleeved or whatever wording you like and that is enough.

Every pipe, water or gas should be sleeved when passing through a wall as the risk of corrosion is the same no matter what is running through (hot pipes moreso because of thermal movement) it but how many run around shutting stopcocks because the hot and cold have been cemented in........no one does.