# David Wilson Homes plumbing



## GPB (25 Oct 2011)

A friend has recently bought a new David Wilson '5 Star' Homes 3 bed house with ensuite shower room and fitted with a combination boiler.

After about 2 weeks the whole ground floor flooded due to a 22mm plastic elbow on the rising main blowing apart in the kitchen ceiling void. They blamed this on water pressure too high, then a dodgy fitting.

Following several weeks using specialist equipment to dry the screed out again, they are now in the process of replacing dry lined walls, bit of ceiling, kitchen, doors, flooring, etc. Unfortunately yesterday they had another leak which means more drying out.

They've now chopped into the walls and cut large holes all over the kitchen and utility room ceiling and replaced all 22m plastic pipe with 15mm from the mains stopcock onwards, including that in the ceiling void.

From my limited plumbing experience (admittedly with roof tank, immersion heater, etc) I've always used 22mm pipe from the stopcock, with 22mm going to the bath, roof tank, and branching off with 15mm for sink, basin, etc.

Before I make a fool of myself, please could anyone with more knowledge tell me if they think 15mm from the stopcock under the sink onwards is ok? Is it likely to be noisy? Will they be able to fill a bath and use the electric shower at the same time? Any other possible drawbacks?

Many thanks in advance for any replies.

Graham


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## clk230 (25 Oct 2011)

must admit i have limited knowledge same as you but surely if there was to much pressure when using 22mm theres going tobe even more with 15mm.

any plumpers on here ?


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## Sawdust (25 Oct 2011)

GPB":284etf8v said:


> A..Before I make a fool of myself, please could anyone with more knowledge tell me if they think 15mm from the stopcock under the sink onwards is ok? Is it likely to be noisy? Will they be able to fill a bath and use the electric shower at the same time? Any other possible drawbacks?
> 
> Many thanks in advance for any replies.
> 
> Graham



Graham,

I don't know much about plumbing but my house has 15mm pipe from the stopcock onwards and we don't have any problems with it. We have 5 sinks and two showers in the house; it's not noisy and we've never noticed any problems running two showers at once.

Mike


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## RogerS (25 Oct 2011)

Graham

You might be better off asking this question over on Ask The Trades. 

If you are on a combi system for your domestic hot water then your hot water flow rate is going to be dependent on your mains.

Are they using 15mm plastic pipe or copper? What colour is it? White or grey.

I have never heard of this happening and can only put it down to them not fitting it properly. Inserts (the right type) inside the pipe and also, if using the white John Guest fittings, screwing them up tight after the pipe has been pushed in. It could even be something as silly as incorrect/faulty grab rings inside the fittings and/or the 22mm pipe not being 22mm. Extra hard pipe? I know that you can't use push-fit fittings on chrome pipes as the grab rings don't.

it would seem your friend is not alone

http://www.reviewcentre.com/reviews170529.html

David Wilson Homes are now part of Barratt. Say no more.


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## Dibs-h (25 Oct 2011)

Stepping down to 15mm will result in greater frictional losses, so therefore less flow.

They could have easily fitted a pressure reducing valve.

Dibs


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## marcros (25 Oct 2011)

RogerS":1ojgs9eb said:


> Graham
> 
> You might be better off asking this question over on Ask The Trades.
> 
> ...



I would think that it is likely to be the pipe not being pushed fully in. Professionals should know better, but corners are cut and people rush. The instructions say that you are supposed to mark the pipe to show where it should be pushed into, but I havent seen anybody bother on site. They are so easy to use, it is possible that an apprentice did it, rather than something like soldering, where you had to have some idea of what to do.

I used to sell plumbing fittings many years ago, and I dont recall any problems due to faulty plastic fittings. The original john guest system used to have a horseshoe type clip that went behind the fitting, to stop the collect being pressed in. Needless to say, nobody ever seemed to buy these because it was extra effort and expense, and we did have an issue or two where the system had been pressurised, pipe had flexed, and a fitting was pressed against a joist, releasing the collet and the pipe. I dont recall selling many replacement grab rings either for when hep2o was reused!

I would stake my reputation on user error rather than the fittings being faulty.

Mark


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## Jacob (25 Oct 2011)

GPB":15kgbk1c said:


> .... .......... Will they be able to fill a bath and use the electric shower at the same time? ....


Depends on the pressure. 
Electric showers don't need a lot - I think ours needs 3 bar or something. Needed a reducing valve to keep it down. 
Reducing pipe size doesn't alter pressure itself, but could reduce flow, which amounts to the same thing at the end of the pipe run i.e. pressure would fall off faster, with less effect nearer the stopcock.


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## studders (25 Oct 2011)

I have heard of this happening several times, one job done by a pro and several others done by competent diyers. I don't do much plumbing these days but if I do I stick to soldered joints, call me old fashioned.....


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## doorframe (25 Oct 2011)

studders":1tyan9p4 said:


> I don't do much plumbing these days but if I do I stick to soldered joints, call me old fashioned.....



+1. And I only use compresion joints where I have to..... ie... valves etc. I avoid push-fit like the plague, but the pros on site use it 99%.

I replumbed my entire house about 5 yrs ago, when I replaced the boiler/cylinder/tank(s)/ leaking rads etc and all the imperial leaking pipework with metric and a combi. I was told (advised) to keep the DHW to the bath in 22mm all the way, but drop to 15mm at the earliest point when tee-ing off to the sinks and showers, reason being that you'll use much less hot water in the sinks and showers, and want the hot water more instantly, so the thinner pipe will help achieve this. 

I wasn't overly convinced but he was an experienced plumber so I followed his advise and so far no problems.

Roy


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## RogerS (25 Oct 2011)

doorframe":2kb79bxv said:


> ... reason being that you'll use much less hot water in the sinks and showers, .... problems.
> 
> Roy



Tell me about it. We used to have to run off 3 litres of water at the kitchen sink before we got any hot water. And, of course, that also meant that when we turned the tap off, that left 3 litres of hot water wasting away in the pipe. So i fitted a secondary return. End of problem.


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## doorframe (25 Oct 2011)

RogerS":2b3oo7qz said:


> Tell me about it. We used to have to run off 3 litres of water at the kitchen sink before we got any hot water. And, of course, that also meant that when we turned the tap off, that left 3 litres of hot water wasting away in the pipe. *So i fitted a secondary return*. End of problem.



That's way over my head. My plumbing knowledge is poor at best. My boiler is on the top floor (3 storey house with 2 intermediate levels), and the kitchen is on the ground floor. So the longest run for DHW is the kitchen sink. Kept that to 15mm from within 3 feet of the boiler, tee-ing off to the bathroom sink and shower room sink and shower itself on the way down. 

Roy.


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## sparkymarky (25 Oct 2011)

as i`ve said in previous posts push fit plumbing is not in my opinion a safe and correct way of installing plumbing fittings, although it does have its use`s to get out of a tight spot (or up against a thatched roof). push fit manufactures claim that the fitting is safe and leak free for up to 100 years, however on central heating and hot water systems the 100 year date is massively reduced by up to 50 years. when i raise this with other plumbers they say "not my problem i probably wont be around then" which is fair enough but in 50 years i predict that there will be alot more holes in walls and ceilings.
when installing i always solder where i can then compression fittings, a soldered joint or a compressed metal olive on a pipe is always better than a single soft rubber o-ring.

unfortunately in response to the op`s thread blown out fittings is a common occurrence with push fit fittings and i find myself attending numerous water leaks where the fitting has failed and leaked water in the customers houses. from my experance with pipe sizing when i was a plumbing apprentice if you have a bath and a shower then the smallest size of incoming main for this size of house would need to be 22mm as if it was smaller the flow would reduce when numerous taps are open to the point that it could stop the flow switch operating on the boiler so your friends hot water will go cold as the boiler will not realise that there is any flow through the boiler. 
the plumbers fitting a 15mm pipe to help reduce this problem just sounds absolutely stupid they should of fitted a prv if they were worried about high pressure as dibs-h quite rightly said. as a professional plumber i quite often find the plumbers that are working on large developments are no more than fitters and have very little training (that being said there are also some very good plumbers working on large developments).

as a side note for anyone using push fit fittings, most manufactures of pushfit fittings recommend that the system pipe work is air pressureised to 10bar to allow the metal crimping collar to grip and dig into the plastic pipe and also to blow apart any incorrectly installed fittings, the problem being most plumbers are afraid to do this as 10bar is a very high air pressure and they think it might damage the sound joints.


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## GPB (25 Oct 2011)

Latest development - 

DWH have now decided to take the section of ceiling down, remove the 15mm pipework they put in yesterday, and replace with 22mm as it was originally. Without the leaks hopefully.


Many thanks for all the replies, it's much appreciated.

Graham


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