Central Heating Pipes in Wall - how to avoid?

[Bear]

Yet another post (well this is a new house for me!)

Positioned and fixed some shelves over the weekend. Before drilling, scan with metal detector which went mad. Couldn't work out why but subsequently drilled 2-3 inches away from any beeping. No problems. Later check all the rads - all of which feed into the walls at the centre of the rad - bingo must be central heating pipes. Since we still have hot water (and I didn't get wet whilst drilling) looks like I've been lucky (not tested the rads but since as I said, didn't get wet can't see a problem).

Problem now is, metal detector only goes to depth of about 1 inch - so if pipes are buried deeper, what's to stop me hitting them in future? I have many pictures to hang and will undoubtedly want to position shelves etc. in years to come.

I always thought central heating pipes went through the floor. This is a 50's bungalow, recently rewired and central heating upgraded a few years back with combi boiler - guess sticking them in the walls is current practice. Daft if you ask me.

[John]

My combi is upstairs - so all pipes drop down the walls from above..

[The Medway Handyman]

Is it possible that the room has been plasterboarded via the dot & dab method? This tends to confuse detectors - which are flakey anyway.

Keep an eye on the combi presure guage, if it keeps dropping you might have a problem.

If feeling brave, remove the screws one by one & see if you get squirted in the eye!

New builds tend to use plastic pipes & should, repeat 'should' have metallic tape over the pipes for the detector to pick up.

Daft indeed. I've only drilled through one in 4 years though, despite using

2 different detectors.

[John Rumm]

A 50's place probably has solid floors. Means pipes dropping down from the loft is the normal way forward in the circumstance.

[YAPH]

Are your radiator pipes about 8 or 10mm diameter rather than 15 or even

22mm? If so you've got 'microbore' which is often run within the cavities of stud walls, behind the plasterboard of dot+dab-ed walls or even in the plaster course.

[Roger Mills]

Indeed. Even so, it's more usual to find them coming down the *surface* of the wall (possibly boxed in) rather than being buried *in* the wall.

[Dave Plowman (News)]

Only if you have no taste. ;-) Bit like surface wiring. There are no pipes showing in this Victorian house anywhere - except of course rad tails and those inside existing cupboards.

[Bear]

As for unscrewing the screws I don't think this is necessary since if the drill bit + wall plug didn't puncture the pipes, then the screw certainly shouldn't have.

22mm? If so you've got 'microbore' which is often run within the cavities of stud walls, behind the plasterboard of dot+dab-ed walls or even in the plaster course.

Not sure what dot and dabbed walls are, and no clue about microbore (never even heard of it) but any visible pipes from radiators are significantly thinner than in our older house which had a gravity fed central heating systems. I would guess most are 8 or 10mm - the ones for the heated towel rails definately are.

[NT]

Those are microbore. Ubore is bent rather than joined, so you cant assume it will stick to straight lines. In fact, it wont.

A simple solution to your problem would be to use a (small) pointed flat drill bit in a hand drill. These low performance bits will churn through plaster quickly, but when they meet something that requires real drilling performance they're crap, so your copper pipes will be fairly safe. You can make such bits from unwanted or broken drill bits.

[The Medway Handyman]

Prolly not, but if the wall is plasterboard the drill bit only punctures the

10 - 12mm board, the screw goes right through the plug & can puncture a pipe BTDTGTTS

Dot & dab is a method of quickly dry lining a wall. 'Dabs' of plasterboard adhesive are 'dotted' onto the wall & the the plasterboard is basically stuck on. This leaves a mixture of solid blobs of adhesive and voids, which confuses the hell out of detectors.

Microbore is simply thinner tube 8mm or 10mm exactly as you describe & can be copper or plastic.

Microbore pipes are sometimes laid behind the plasterboard to conceal them.

[<me9]

ITYM dots are fixed to the wall with plasterboard adhesive and levelled. Dabs of adhesive are added between the dots, and the plasterboard applied and (temporarily) nailed to the dots. When the adhesive is set, the nails (which have a double head) are removed, and the joints taped and filled, together with the nail holes. Alternatively the boards are skimmed.

And cold bridges where the dabs are, but warmer than a conventionally plastered wall.

[The Medway Handyman]

Never seen that done. What do you mean by 'dots'?

[<me9]

They're little fibre pads, about 2mm thick, and about 38x75mm. Getting these on the wall, levelled correctly is the hardest part. Adhesive that's old and goes off quickly makes it easier.

To set the levels I usually use screws plugged into the wall, adjusting the depth for correct level, then use a straight edge to level the dots vertically and horizontally. You can then end up with a wall accurate to a couple of mm.

[End of tether]

I recently had the aggravation of dot and dab plasterboard with 10mm plastic micro bore piping ‘somewhere’ behind it, move radiator across wall was the request, pipework was horizontal across wall at valve height toward a corner then it turned vertical somewhere’ near the corner, the pipes if gentle drilling for new rad fixing (fancy tall narrow radiator) would move aside safely but if enclosed in a’dab’ of board adhesive were undetectable plus the meandered up the wall in an approximate width of 14” so a minor disaster waiting for the unwary, a bit of metal tracer wire or similar would have saved hours of messing around, formerly I was an electrician and regulations are strict on cables straight up above or below outlets and protective metal covers too, so beware plastic pipes folks, it did occur an infra red imaging detector might help when the heating was still flowing to show hot areas but at hundreds of £££ not really an option for the average job

[Vir Campestris]

Ah, wonderful HoH... "posted 12 years ago" it says :P

I've been close to that. I found where my radiator pipes were by the simple method of mounting the wireless thermostat on top of them. It didn't puncture the pipes, but it didn't work too well either!

(it turns out they run across the ceiling of the old part of the house, down the wall, under the floor of the new extension, then to the radiator on the opposite wall)

Andy

[Brian Gaff (Sofa]

Why don't they make plastic pipes with a strip of foil down them for aiding finding many years later on.

As for 12 year old posts, well it is home owners club, which as we know is incapable of making the year of the original posting obvious or indeed quoting in any meaningful way, nor does it warn that inlaid photos links get lost on an ascii newsgroup. In my view the main problem is that the Usenet committes have not banned this non complient website from having access. Brian

[Tricky Dicky]

My daughter was told by the developer when she moved in to use a stud/pipe finder as the pipes although plastic were wrapped in foil insulation.

Richard

[Chris Hogg]

The CH pipes in my bungalow have triple layer walls, an aluminium central layer with 'plastic' inside and out. They respond strongly to my pipe detector set on 'metal'. There's almost certainly a brand or technical name for that design of pipe but I don't know it. Nor can I find a convincing image.

[Andrew]

I thought they had a metal layer to form the oxygen barrier ?.

Do metal detectors recognise this layer or not ?.

Andrew

[Andrew]

Speedfit claims to be 5 layers.

See the technical data here (it's long way down).