gas pipes outside the house

  WhiteTruckMan 06:42 AM 25 Aug 12

In case anyone was wondering about the increase in the local moth population, it's because I've finally decided to pry open my wallet and splash out on a new boiler. I've had several quotes, and the one I am most likely to go with has made a novel suggestion that I dont know what to make of that nobody else has, and I thought I would run it by the forum to see what people thought of it.

I need a new gas supply pipe. I'm not disputing this, as they have all told me the same thing. The old one is 15mm, and I need a 22mm pipe. But where it gets inteeresting is that it has been suggested that instead of a somewhat convoluted routing of the new pipe, they simply bore a hole through the outside wall and run the new pipe up the outside of the side of the house then back in at the new boiler.

I've never even heard of this sort of thing being done before, let alone seen it. The side of my house has a driveway, so in theory there is no public access, but I'm concerned about a number of things, namely metal thieves, accidental damage, and weather. Do gas pipes freeze up in winter if above ground?

The fitter said he'd done quite a few like this, with never any problems, but he would say that, wouldnt he? I checked his gas safe card, along with picture, and he's qualified, so it should be legal. But that doesnt necessarily mean it's a good idea.

Has anybody any thoughts or experience in this sort of thing?


  morddwyd 07:07 AM 25 Aug 12

Like many, my gad meter is in a plastic box on the front wall.

The pipes are exposed to frost etc. below the box, and the plastic box is no protection against even a small hammer.

I've never heard of any problems, but a longer length of pipe may be more attractive to thieves, particularly in some parts of the country.

  wiz-king 07:46 AM 25 Aug 12

It's common practice to run gas pipes outside from a meter box to the entry point for the kitchen/boiler. I have seen some that go around two sides of a house.If it's a sraight run you could hide it a plastic cable conduit trunking strip if it matches the outside of the house (rendered) or use a cable guard.

  Quickbeam 07:58 AM 25 Aug 12

Yes it's quite common now, my neighbour has the same type of external fitting as you describe. The reason is of course cost. If you want it hidden within you'll have to pay more.

It'll also involve a lot of internal upheaval in the way of carpets back and floors up, possibly some wall repairs as with rewiring. I had mine rewired in the spring and the new feed to the garage was done in the same manner, through the outer wall from the consumer unit and an armoured cable clipped along the outside into the garage. The alternative was to dig the driveway up to fit it as per the original feed.

Now that you're aware of this type of gas fitting, take a local walk, you'll see them now that you're aware of it and know where to look. In reality it's no more visual than normal external soil pipes.

As for the metal theft worry, if you expect to have your garden gates nicked as a matter of course, it's then not recommended:)

  Forum Editor 08:26 AM 25 Aug 12

Running gas pipes on external walls is a common practice, and complies with Gas Safe codes of practice, so no worries there, as long as the pipe run goes by the shortest possible route, and is properly clipped to the wall. As your installer is Gas Safe registered I'm sure that will be the case. He should sleeve the pipe through the wall in a plastic conduit, by the way. This can subsequently be filled with expanding foam to seal any gaps.

There will be no danger from frost or weathering - the pipe will do good service for many years.

One quick point worth knowing. Modern combi boilers have self-moderating burners, and when they go at full blast there's a considerable gas demand. In some cases where pipe runs are long, or contain multiple changes of direction it's advisable to run 28mm pipe from the gas meter to within a metre or so of the boiler, especially if there are branches that feed a hob, or any other gas device. The reason for this is that a big demand from the boiler when it fires up can cause a sudden drop in flow to the ancilliary devices, and if a hob is a few years old it may not have a flame-failure device. This could mean that a hob burner that is on a low setting could go out, and then, when flow is restored to normal it could allow unlit gas to escape into the room. It's unlikely to happen in most modern homes, but it's worth mentioning. Gas regulations are very strict on these matters.

  Forum Editor 08:37 AM 25 Aug 12


"Wife's friend just got her house rewired and they took the wires out of the house through the wall and ran them round the side of the building the same way as they do the gas pipes nowadays."

I hope the electric cables were enclosed in round PVC conduit, carefully clipped to the wall? It's OK to run cables in this way (It's often done to get power up to a loft conversion) provided all cable is enclosed in conduit.

  Wes.Clox 09:56 AM 25 Aug 12

Unsure if this will work.

We have just had a full rewire and new combie central heating. The old boiler was in an out house just to the right of the light, inlet now bricked up. The new combie boiler is where the old airing cupboard is in the centre of the house. One gas pipe goes to this, the other to the gas range in the kitchen.

External gas pipe

  Woolwell 10:48 AM 25 Aug 12

I've had an external gas pipe to a re-posiitoned combi boiler for several years without any snags at all. However if you have an external condensate drain pipe from the boiler then you need to make sure that it doesn't freeze. Regrettably part of mine does freeze.

  Fruit Bat /\0/\ 14:12 PM 25 Aug 12

Yes done similar.

Removed old boiler from kitchen and old hot & cold water tanks from airing cupboard. Moved one radiator and changed five.

New Combi Boiler fitted in airing cupboard. Ran new 28mm copper pipe gas supply from meter through wall, up outside wall and back into airing cupboard. Had gas safe man into to connect, test and provide certification.

My neighbours had freezing problems last year with condensate drains 15mm pipe so have 15mm through wall into 28mm on outside which will prevent blockage by freezing.

Just realised that the Kitchen and bedroom above (that used to get really hot) will be affected by the move as no heating in kitchen now boiler is moved and pipes that ran under bedroom floor from tank to boiler are gone, I'll have to turn the radiator on in the bedroom :0)

Next job is replaster and new kitchen, anyone recommend good heaters for kitchen, thinking of the sort that fit under the base units and blow hot air out at floor level

  oresome 14:24 PM 25 Aug 12

It seems standard now to run gas pipes and the condensate drain pipe externally.

It does make the house look ugly and I wouldn't like it. The houses were originally built with internal soil pipes, so otherwise have an uncluttered external appearance.

I personally would also avoid a combi boiler, prefering a system boiler with hot water storage tank, allowing the backup of an immersion heater. The boiler itself can be much smaller and the gas supply pipe remain at 15mm.

  wiz-king 15:03 PM 25 Aug 12

oresome even with a system using a hot water tank most modern boilers need a 22mm gas pipe to be sure of the initial start-up gas flow.


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