Gas down to garage (again)

[Paul J S Green]

I need to run gas down to the garage which is about 20 odd metres away from the house at the bottom of the garden.

i've discussed this on the group before and received a lot of help.

after a lot of consideration and soul-searching i've dug a trench about 18 inches deep all the way down (i need to run water, etc - NOT ELECTRICITY in this trench, that's separate).

my main question at this point is, can i run yellow plastic mdpe down the trench - this seems common sense, but there seems to be a slight grey area in the regulations dictating that all pipework after the meter needs to be copper (sometimes shielded by yellow plastic coating) - this mainly comes from google groups search.

also, i only want to run a simple combi boiler (don't know what type yet, but unlikey to be beyond 100,000 btu) so will i get away with

32mm mdpe?

thanks in advance for all help.

paul

email replies to paul dot green at totalise dot co dot uk - freeserve address duff!

[Ed Sirett]

I beleive that all installation (cf service) pipework must be copper or steel. Even 28mm/1" pipe work will likely be marginal for a 20m run and 24kW.

It may turn out to be considerably cheaper to let transco put the pipe in for you by requesting a new gas supply, they will lay yellow MDPE but _their_ pipe will be under more pressure and can therefore handle a bigger pressure loss.

[IMM]

28mm will give about twice the requirements.

20 metres of 22mm will give: 2.9 cubic metres 20 metres of 28mm will give: 5.9 cubic metres

Looks like a mixture of 28 & 22mm would do.

I assume this is after the meter. I personally see nothing wrong with running yellow plastic pipe as long as it enters the building as per plastic mains pipes; terminated immediately. I would install a maintap isolator in the remote building.

I can't say I have read anything that specifically says all pipes after the meter "must be metal", although the last time I read BS6891 was a long time ago. Plastic cannot be overground, except the short piece on emerging.

[Paul J S Green]

I intended to terminate the connections as transco would, buying all the stuff off BES.

what plastic diameter would do - 32mm outside dia?

i would just want to run a relatively small combi to heat a 7m by 10m garage (insulation getting better on an ongoing basis) and maybe up to

12l/min hot water.

thanks again paul

[Ed Sirett]

Well you can use MPDE and I would say it will have to be 32mm (effectivly

1" ID) to run the 24kW you'll be looking for. I have seen an 18kW combi but that of course will have a very low flow of HW.

The transition from metal to MDPE will take place below ground and the metal parts below ground will of course be corrosion protected.

375mm minimum depth under drives and 50mm elsewhere.

Warning tape to be placed in the backfill of the trench.

[dcbr26117]

For starters mdpe isn't allowed to enter the building, entry and the first 1m should be screwed iron.

Do you have an industrial gas ticket, if not get a corgy registered engineer with the correct qualifications to install and test it.