Water pipes behind built in electric oven?

[Albumen]

I'm re-routing some water pipes. CH Flow and Return, Hot and cold supplies.

I've just realised that I'm running them, horizontally along a wall in the kitchen, where there's probably going to be an electric oven, built in. With either an induction or gas hob above.

Questions:

1. Do built in ovens usually go right back to the wall? In other words how much space will I have.

2. Are there any regulations about this?

Obviously I'll try to get them as far back as possible and avoid joints right behind the applicant. I was going to do it in plastic, but I think I'll do at least that length in copper now and chase the plaster out to get it them further back.

Many thanks.

 

[PrenticeBoyofDerry]

Questions:

1. Do built in ovens usually go right back to the wall? In other words how much space will I have.

There is noramlly a space behind them but different models will offer differing spaces. Some barely give space for a plug. But the pipes would be best run in void under the cabinets.

2. Are there any regulations about this?

Yes there are for both electric and water
External influences, for electric and undue warming for cold water.

Obviously I'll try to get them as far back as possible and avoid joints right behind the applicant. I was going to do it in plastic, but I think I'll do at least that length in copper now and chase the plaster out to get it them further back.

Remember copper does not like limestone (it corrodes), so if chasing out in to mortars, the pipe will need protecting.
Also remember there are permitted depths in which you can chase in to the leaf/skin of bricks/blokes etc...

 

[Albumen]

Thanks for the response. Thinking again about it, plastic is probably better, if I can get the connectors away from where the oven will go. At least with plastic I can gently bend it the way I want it whereas with copper I'll have to do lots of bends, which I'm used to doing but not as easy.

Plus plastic pipe doesn't need protecting from mortar?

None of this will actually be connected, are there still regs that apply? It's a modern consumer unit with RCDs on every circuit. So supp bonding is now irrelevant maybe?

One horrible thought is that I do this, all nicely tucked out of the way and then the oven fixes to the back wall where my pipes are. Is that how oven fit? Or are they just fitted to the cabinet they're in?

 

[PrenticeBoyofDerry]

Do you know the type of oven you are getting?
A standard built in oven will be fitted in to an oven housing, (an opened back base unit). so the oven is seated within this housing.
There will be avoid of about 150mm below the base of the housing, you can route pipe work there and it will not encroach the space of the oven.

 

[Albumen]

Not really. But almost certainly electric. But thanks for that info. So I could just run them along the floor? Think of the fortune it would save me in pipe clips!!

Unfortunately I can't actually do that at the moment, because that's where the current cooker is. I'm tempted for now to sink them as far back into the wall as possible, without actually chasing any brickwork out. It's all going to be white Hep2O, which is demountable with the little tool thingy, so if necessary I can reroute if it doesn't work out.

 

[PrenticeBoyofDerry]

You would still need to clip the pipes regardless of in chase of on for, because if not clipped securely (there are requirements regarding pipe clipping distances, copper and plastic pipe spacing will be different) the pipe work could suffer from what is known as "water hammer", this is where the pipes will rattle and bang.
You must also keep the cold water pipe at a good distance from hot and C/H pipes. If mounting horizontal install the cold water pipe below any hot and C/H pipes to prevent warming of the cold water pipe. If cold water pipes are warmed you could end up contaminating the cold water. Might be worth consider lagging them, this will also help with undue warming and offer protection from external influence to any electric cable.

 

[Albumen]

Thanks.

Only joking about the clips, obviously.

The pipes as installed, by heating engineers, are run exactly the way you say they shouldn't. A horizontal run of five pipes, from top to bottom:

CH
Cold water
Gas
Hot water
CH

Never noticed the cold getting at all warm, except for the very first run off if a mixer tap has been on hot, and then changed to cold, where I assume that the cold inside the mixer tap is getting heated.

Why would cold water getting warmed lead to contamination?

 

[PrenticeBoyofDerry]

Why would cold water getting warmed lead to contamination?

Bacterial growth, when water starts to get warm micro-organisms thrive.
Cold water temperatures must be regulated to control this.
In your set up, as the gas pipe is directly under the cold water, the likelihood that any heat would be dissipated from pipework beneath is less.
But ideally the cold water should be at the bottom as heat rises, but if the gap/spaces is large enough between pipes then the hazard is greatly reduced.

 

[Albumen]

Thanks. I've never notice the water being anywhere near tepid, and where the pipes run horizontally they are not boxed in or anything, and they're in a cool part of the house, so heat is probably dissipating.

I usually fill the kettle from the hot, and if I'm going to drink cold first thing I let the tap run, like we used to with lead plumbing.

 

[PrenticeBoyofDerry]

That's all well and good but you asked this question
2. Are there any regulations about this?
So I informed you of them!

 

[Albumen]

Thanks for your help. I didn't really mean regs about the order of water pipes, but thanks for the information. Is that a regulation then? That the cold water shouldn't be above hot pipes in a horizontal run? Nobody told the plumbers who put them in then.

The regs I meant were running water and gas pipes behind an inbuilt oven.

Thanks

 

[PrenticeBoyofDerry]

No fitting shall be installed that it is likely to cause contamination of water to any pipe supplying cold water to domestic properties this is to prevent water being warmed to above 25 degrees C.

The regulation for distribution temperature of water, schedule 2, section 4, (R9.1)

It is recommended that hot water to be stored at not less than 60 degrees C, hot water to be distributed at not less than 50 degrees C, cold water stored and/or distributed at not more than 20 degrees C.
Pipes serving cold water taps, should be as short in length as possible, should be installed to prevent heat gain from adjacent hot water pipes or other heat sources.
The relative positions of cold water pipes to hot water pipes, should be so they are not warmed.
Horizontal cold and hot water pipes, should be fixed so that the hot water pipe is at a higher elevation than the cold water pipe.

Gas pipes: a gap of at 25mm between cable and 15mm-35mm pipe, a gap of at 50mm between 35mm plus pipe.
150mm gap between gas meter and associated fittings and electric meters, switches, socket, controls etc...

It's common sense, you are trying to prevent potential hazards from the environmental conditions and external influences.

 

[PrenticeBoyofDerry]

.


Gas pipes: a gap of at 25mm between cable and 15mm-35mm pipe, a gap of at 50mm between 35mm plus pipe.
150mm gap between gas meter and associated fittings and electric meters, switches, socket, controls etc...

Gas regulations
separation of gas installation pipework from other services.

BS6891:2005+A2:2008 (8.16.2)

 

[Albumen]

That's great, thanks.

I think I'm pretty much complying with all of that, at least where I'm not I'm not making it any worse than what the installers did. Considering they put the gas pipe through two walls, unsleeved, and cemented it in, I've got less concerns about my work than I have about theirs.

But going through it piece by piece.

Separation of gas and cables, yes, that's fine.

I usually set the hot at 75 at the combi, and part of the work I'm doing is making the path shorter, so OK.

Cold too is now getting a shorter path from mains supply to taps.

Only thing is cold is higher than both the DHW and the CH Flow. These pipes go, from top to bottom:

Return
Cold supply
Gas
DHW
Flow

That's about an 8 foot run. But like I said, not boxed in or anything. And on that run it's on its way to the boiler. In other words the cold is going to be heated anyway. But maybe it means the hot isn't really potable. First thing in the morning I've been filling the kettle from the hot tap, but thinking about it that's hot water that was once cold water being gently warmed by the CH Flow pipe, maybe. But not much.

But filling from the cold and letting it run a while probably still a good habit.

 

[PrenticeBoyofDerry]

If you are boiling the kettle would not make any difference as far as contaminated cold water is concerned, once boiled bacteria would be killed.

The issue about the cold water going to the boiler, becoming warm along the way, is not a concern. Well if you have back flow to the cold water taps then it does become a problem.