15mm gas pipe for boiler

[silverback]

Looking at the Ri instructions it says that the gas connection is 22mm, this would mean that a 22mm supply is needed, as you cannot reduce the inlet supply

I dont see how you can logically come to that conclusion!

It is as perverse as those who think because Vaillant have a 15 mm gas inlet the whole gas supply can be in 15 mm.

The gas supply has to have a minimum pressure drop of 1.0 mB. Thats the only criteria.

Many makers say the gas supply has to be 22 mm. Thats only because otherwise cowboy installers would do it all in 15 mm.

It says in the instructions that the Gas connection is 22mm, now I don't fit Worcester so I don't know, but if the gas connection is 22mm then it needs to be connected with 22mm, do you think your Gas Safe inspector would except you connecting a boiler with 15mm when it has a 22mm connection at the boiler, I don't think so

 

[silverback]

From the Worcester web site with regards to the 18Ri.

Under no circumstances should the size of the gas supply pipe be less than that of the appliance inlet connection (22mm diameter).

Also from the Worcester web site for the 18Ri and this is from the installers section

Greenstar 18Ri and 24Ri and Greenstar CDi regular models

Under no circumstances should the size of the gas supply pipe be less than 22mm.

Now that to me clearly says the supply must be 22mm, it does not look like a statement just for cowboys, although cowboys would not bother looking at the web site

http://www.worcester-bosch.co.uk/installer/boilers/gas-boilers/greenstar-18ri/supply-requirements

 

[ALEC1]

gosh the poor OP, he queried his installer and he now sees the dilemmas all installers face...

 

[silverback]

gosh the poor OP, he queried his installer and he now sees the dilemmas all installers face...

Exactly, there is never clear and concise information, but in the case of the Worcester 18Ri it does state that the gas connection is 22mm, as I said previously, I don't fit Worcester boilers, so have not fitted one of these, but all I know is when I get a boiler with a 22mm gas connection at the boiler, i ensure I run 22mm to the boiler.

 

[Agile]

In virtually alll cases a 22 mm supply is needed unless the meter is in the same cupboard!

It never causes the boiler a problem is a larger gas supply pipe is used.

The makers suffer from real nupty installers who dont upgrade the gas supply.

I am doing an upgrade throught the loft, out the back and back in behind the boiler. All easier because they were having a new roof and had scaffolding up!

 

[silverback]

Tony, it says in the instructions that the gas connection to this boiler is 22mm so it does not matter if the meter was right next to the boiler, if the gas connection on the boiler is 22mm then the supply at that connection must be 22mm

 

[Agile]

Well obviously it needs to be a 22 mm connection to fit but if only say 1000mm to the meter then it can then be reduced to 15 mm.

The only requirement is that the presure drop is less than 1.0 mB.

 

[silverback]

Well obviously it needs to be a 22 mm connection to fit but if only say 1000mm to the meter then it can then be reduced to 15 mm.

The only requirement is that the presure drop is less than 1.0 mB.

I disagree with that, if the manufacturer supplies a 22mm gas connection on their boiler, then it should be connected in 22mm as as it sates on the Worcester web site, you should not reduce this connection

 

[simond]

Me too.

Come on Tony, you know the rules. The manufacturer instructions over-ride the gas regs and Worcester are absolutely clear about this requirement, unequivocally so.

If you talk to Worcester at length about it, they will tell you that they will review each case on it's merits but there is really no excuse for following their instructions, whether we believe them to be unnecessary or not.

Every ACS card holder should know how to size pipework correctly but we also are told in our gas exams, verbatim, that for domestic sized works we follow manufacturers instructions where these specifically differ from general practice.

If you willfully do not follow your training then you are not a responsible installer in the view of the licensing authority - with all that entails.

 

[gasanstuff]

I recall Worcester releasing a tech article which allowed the use of 15 mm gas pipe on the 12 and 15 ri. 18 ri and above must have a minimum of 22mm ( think they state that no part of gas pipe is allowed to be smaller than the inlet connection. I am a Worcester accredited installer, I dont have a letter allowing me to fit boilers on small pipes. I just install them as they should be installed as per MI.
Hope this helps

 

[simond]

Spot on.

 

[Agile]

I know what they say and I also know that its because they have so many problems with installers who dont connect the proper gas supply pipe sizes.

If I was installing one then I would use at least 22 mm tube all the way if it was 18 kW or larger.