Combi gas pipe question

[Ford Prefect]

Morning,

I'm fitting my central heating at the moment - after putting it off all summer, the weather has focused my attention on it now.

I'm going to get quotes for the installation, but I'm a bit confused about the gas pipe. The boiler (Vaillant ecomax 828) needs a 15mm gas input. However, I've read that I should use 22mm for boilers.

Does this mean I run 22 all the way from the meter to the boiler, and then fit a 15mm reducer just before the connection? Or does it just need to be 22mm up to a point, then split into 2 15mm, one to the boiler, one to the cooker (to be fitted later)

Hope someone can help on this,

Andy

BTW, I'm not connecting the gas pipe to the meter or boiler, just laying out the route - I'm getting a corgi in to do the notifyable stuff.

[EricP]

This is a skilled job requiring calculations. Let the Corgi bloke do it. It won't cost much more as he is on site anyway.

If you get the pipe wrong he will refuse to connect it anyway.

[Ford Prefect]

Thanks for that, I'll just do the chasing out for the pipe run, and let the expert do the rest then..

[John Rumm]

In general, yes you run a bigger pipe and drop down in size either as you go into the boiler, or a short way before it.

Have a look at the sizing tables here:

is a worked example using these in a recent thread here:

[Andy]

Usually the combi manufacturers say 15mm is OK for the last metre ( or less ). As has been mentioned really you need to calculate whether the pipe you plan is OK taking into account other appliances demands and the effect of elbows etc. If elbows are making the effective length of the pipe too long try using sweeping curved bits of pipes to make your own, wide radius elbows, as it were.

If you do it yourself make sure you clean up not only the pipe where it is to be soldered, but also the inside of the couplers/elbows etc, with wire wool.

Andy

[fred]

As John says 22mm is likely, my own boiler has a 15mm inlet and I ran it in 22mm then reduced it to 15mm for the last 150mm or so. Having done the calculations myself I'd say it is unlikely to have a run of length with less than 22mm being suitable. That's not to say I haven't seen plenty of 'professional' jobs done in clearly inadequate runs of 15mm.

[Ford Prefect]

Thanks for all the advice. I think I'll run the 22mm from the meter to the boiler and let the installer sort out the 15mm bit.

[EricP]

Bet he says "why did you use 22mm???"

You are in a no-win situation and have decided on the best course of action. :))

[John Rumm]

Just to clarify, you may find that even 22mm is not enough in some cases

- hence why you need to work out the maximum gas rate required and then work out the pressure drop at the required length.

Rather like the famous example Ed posted a while back:

[Guy King]

The message from John Rumm contains these words:

[Ed Sirett]

That was only supplying a cooker (11kW) but even so.

[marcusb3495]

if you are trying to fitt a gas boiler and not quallified to do so

--you can be prosecuted

this is not the site to get imformation as most are diy ers and from i have seen CAN give BAD ADVISE i am a fully quallified and it costs me a fortune to keep to up to date howerver

22 from meter--last meter 15mm

howerver depends what you have gas wise

good proctice to put 28mm in from the meter --

and do not put the vaillant onto olds rads and pipework because i will gaurentee if its a combi the diverter will go

Ed Sirett wrote:

[Andy Hall]

Take a read of the Gas Safety (Installation and Use) Regulations 1998

3 (1) says (and I quote)

1. - (1) No person shall carry out any work in relation to a gas fitting or gas storage vessel unless he is competent to do so.

Note that the word "competent", not the word "qualified" is used.

While I can appreciate that you do have difficulties with the use of English, the meaning of the two words is quite different.

This is not a "site" - it is a Usenet newsgroup.

Really? Presumably there is no written test if that's the case......

Is that what you tell all of your customers in an attempt to increase the amount of work allegedly needed?

Presumably you don't do written quotes stating this? Do you have numeracy as well as literacy problems?

[Guy King]

The message from "marcusb3495" contains these words:

Who says. You don't have to be qualified, just competent, and if it's your own system you're free to get on with it.

[David Hansen]

On 2 Nov 2006 14:13:42 -0800 someone who may be "marcusb3495" wrote this:-

Really.

Assuming one is working on one's own property and is competent to do the work (which essentially means being able to make proper joints and test for leaks, though there are other things to do with combustion in some circumstances) then the Labour Party haven't yet made it illegal to work on gas. No doubt they have plans to do so and thus put money into the pockets of various groups as part of their nanny state agenda, but they haven't done so yet.