gas supply pipe

[srp]

I was contemplating replacing my rather aged Potterton Lynx with a nice new boiler. Browsing through the install information for the Worcester combis. I see that they can require a 22mm gas feed from the meter. Is this a typical requirement ? The Lynx boiler has what appears to be a

15mm gas pipe, which is completly concealed in the wall , replacing this would be a major PITA I reckon... So my question is... What Kw output can you get from a 15mm pipe these days, Or more specifically what boiler will work on that size pipe ?

Simon

[andrewpreece]

It's more complex than that. The resistance of pipes to gas flow goes up very fast as you shrink the pipe diameter and increase the demand . There are ways to calculate the size of pipe you need available on the web. It also depends on how many elbow joints are in the path, and what other appliances using gas spur off from the main 22mm supply pipe.

Typically you can get away with 22mm pipe from the gas meter to within 1m of the boiler, then feed it with a 15mm pipe, but you'd be better off Googling a bit to find a website with a set of formulas or reckoning tables on it.

Andy

[Andy Hall]

You have to look at the lengths of the various sections of pipe to know that.

If the 15mm length is very short, it may not matter, but flow gets much worse with length.

There is a useful application note on the Copper Development Association web site on how to calculate this in accordance witht eh requirement to achieve no more than a 1mB pressure drop.

[Ed Sirett]

Yes, but see FAQ.

The Lynx boiler has what appears to be a

Gas rates will be similar so pipe work should be the same but existing installation is probably sub-standard.

[Rod]

"andrewpreece" wrote in news:42f20039@212.67.96.135:

Not disagreeing with you on a logical or practical basis (I don't claim to know enough to do so!), but the WB installation instructions are categoric that this is not allowed.

[sploop]

Hi, have to run gas to an island cooker. Floor is concrete. Anybody know regs for putting pipe in floor re insulation, depth etc. Thanks all

[Sponix]

All I konw is that it shouldn't have joints if possible..if it does then they MUST be soldered.

sponix

[Sponix]

..and the copper mustn't come into direct contact with the concrete...

sponix

[Christian McArdle]

Nope, but do run two, so you've got a spare! (This particularly applies to the water pipework, if applicable).

Christian.

[Richard A Downing]

Why, what happens to copper in contact with concrete?

R.

[EricP]

It eats the copper pipe.

A friend is waiting for the plumber to dig his 15 foot hallway up at this moment to replace the mains in. Vax is his friend.

[sploop]

That sounds like a sleeve, tight fitting no room for gas to collect??? Any ideas what type ans fit??? Thanks guys

[Andy Hall]

Corrodes. The solution is to wrap in Denso tape or equivalent to protect it.

[Antony]

If you need to ask this, maybe you should get a CORGI in to do the work?

You can get upvc channel that you embed in the concrete, with a cover that fixes over the top. No problems then with the pipe being in contact with the concrete, and it should be accessible later depending on the floor covering. If you intend to embed the pipe in cement, either wrap in Denso tape, or buy yellow plastic sleeved copper. BES sell it. I'd fit an isolating 1/4 turn gas valve before the point where it goes into the floor, so you can cut it off later. You'll also need to use fixed pipework all the way to the hob - no flexible or demountable connectors allowed.

You'll also need to check the pressure drop - don't assume 15mm is sufficient. Also don't assume you can't use 10 or even 8mm pipe instead

- but you won't know without doing the calcs.

-Antony