Gas pipework from Meter to Boiler under concrete

[DeanS]

Hello,

 

We have started a new build and are soon to start laying services.  The house is a PassivHaus and the floor structure is a concrete slab sitting on 300mm of insulation.  Most of the services (water, electrics and telecoms) are coming into the house through ducts (blue, black, orange respectively) which then need to be made airtight (a headache as I understand).  Using duct is great because we never liked the idea of services being set beneath the slab never to see the light of day again and impossible to do anything with if they leak / fail or if we need to upgrade etc.  And, duct is relatively cheap and futureproof and with grommets, tapes, care can be made airtight.  All great.

 

But, we are struggling a little with the gas supply.  The meter will be in a half-buried box at the front of the house and the boiler is some 8m away in a utility room.  The current proposal by the plumber is to run copper pipe from the meter to the boiler below the slab + insulation.  We trust the plumber and he is corgi qualified, but the idea of copper pipes with joints sat in the ground below 0.5m of concrete, steel and insulation doesn't sit particularly well.

 

Does anybody know of any alternatives?  Options we have discussed with the contractor are:

 

1. Run the pipe on the external elevation and enter the building close to the boiler (but, there is limited space down the side of the house where the pipe would run).  And, its a bit of an ugly and seems mad to run pipes around a new build house.
2. Run the gas pipe in the french drain that runs around the house, perhaps in perforated duct, and then up through the building close to the boiler (again, as above, space is limited).  But, aesthetically much better than option 1.
3. Run the gas pipe in a duct under the floor, perhaps using TracPipe or similar.  But, we understand this needs to be vented which may cause issues with airtightness.  If the duct is non-perforated and we seal the duct to the airtightness later in the floor then cap externally, this could work.  Otherwise, can we cap internally and vent externally?
4. Move the meter inside into a meter cabinet and run the pipe in duct internally (as both ends of the duct are internal, airtightness is less of an issue).  This would put the meter in a ground floor bedroom, which is not ideal.
5. Move the boiler closer to the meter (but, current house layouts do not permit this).

 

Of these options, number 3 would be ideal, then perhaps option 2.  But, I wonder if there are other options we should discuss with the contractor?

 

We would really appreciate peoples view on our preferred options or any other options that are robust (i.e. flexible / futureproof and pipe not set under a slab) and that comply with regs.

 

Thank you in advance.

 

DS

 

[Russell griffiths]

Why not use an Alpex type pipe ?  

This is like a polyplumb type thing with an aluminium core, our gas was done with this no joins at all. 

comes on a coil in a sort of stiffish configuration would need straightening out to push through the ducting. 

One conection at the metre and one at the boiler. 

 

[Nickfromwales]

Trac has been mentioned, but there's also this stuff. 

 

1 hour ago, DeanS said:

Run the gas pipe in a duct under the floor, perhaps using TracPipe or similar.  But, we understand this needs to be vented which may cause issues with airtightness.  If the duct is non-perforated and we seal the duct to the airtightness later in the floor then cap externally, this could work.  Otherwise, can we cap internally and vent externally?

 

Venting a gas run at one end is permissible. Cap at the house side and make the external end the open end, thus satisfying the requirement to vent the duct. Basically the requirement is there to allow escaping gas to vent and be discovered / detected. 

 

[AliG]

This thread got me thinking. In the extension on my current house the pipe is run behind the stud wall between the meter and the boiler. I wondered why this wasn't being considered as an option. I did think it was unusual at the time it was done and I did wonder if there were issues with it.

 

So from reading up on it now, you can run it inside a wall but it is not ideal and it should be vented to prevent gas build up in the event of a leak. I believe that the wall my pipe is inside is open to the loft above.

 

However, it has now got me thinking the same question in my new place. The gas will come in next to the boiler, but there are 2 gas fires 30m away at the other end of the house, how do I get the gas there? I will check with the builders tomorrow, they either already have a plan, or haven forgotten that they need to get it to the fires.

 

Reading up on TracPipe it seems that it is rated for being buried directly in concrete/screed. Only the ends where there will be joints need to be in a ventilated area. This is where the meter and boiler are so should be fine. So in option 3 as suggested above the TracPipe would not have to be in a ventilated duct, it could be inside the concrete floor so there would be no issues with air tightness. Is this correct?

[jamiehamy]

My understanding from having two cars on lpg is that gas being heavier than air,  it needs to vent downwards to the ground. This is supposedly one reasons cars on Lpg are not allowed on the Channel Tunnel trains. Same with my camper - the vent goes down through the floor. 

 

If gas is run below the slab,  is there not the same risk on gas being unable to escape?   

[dogman]

I used gastite coil. It is set in the concrete slab which i understand is allowed . Comes in rolls and different diameters to match your supply needs.It is stainless steel in yellow plastic