Water pipe upgrade?

[smudger29]

I'm in the middle of converting a 2 bed bungalow into a 5 bed house. Plans are for two baths and 4 showers - my Plumber suggested a 300 litre unvented hot water system and has installed an Ariston product which works quite well with the only operational shower I have just now however - the pressure drops when I run the tap in the same bathroom so I'm worried the system won't be up for four showers in the future.

The Builder carrying out the conversion suggest the problem is down to the flow being restricted by old (1920's) water main and suggested upgrading to modern large dia plastic pipe (cost £500 which sounds reasonable) however I've just noticed he's laying out 20mm blue pipe where I was under the impression most people upgrading water pipes are talking 25 or 28mm. Is the 20mm pipe going to do the job or should I mention this before the pipes installed?

Thanks for any advice - I don't want to pic fault with the builders work but do want this to be an improvement and solve the problem.

 

[chrishutt]

For the set up you describe I'd go for 32mm minimum. There's little difference in the cost of the tube and even the fittings are still reasonable at 32mm, so why put in less and give yourself problems?

 

[sturharv]

If the old supply pipe is lead then the supplier company i.e. United Utilities should offer a free connection

 

[smudger29]

Sure - I just wanted to check there wasn't a positive reason for only using 20mm pipe - Pressure won't drop as a result of the increased flow will it?

If there is minimal cost difference why having gone to all the trouble of digging up my drive does the builder supply 20mm pipe doesn't make sense?

 

[chrishutt]

why having gone to all the trouble of digging up my drive does the builder supply 20mm pipe ?

Because he isn't a plumber. If you want decent plumbing get a decent plumber.

 

[smudger29]

The 'Plumber' who supplied and fitted the unvented tank is the builders plumber and he's the one that's laid out 20mm pipe ready for connection.

is there any reason ( other than saving a few pounds) why a builder and a proffessional plumber would opt for 20 over 32mm supply could it have someting to do with the water authorities supply to the stop cock?

 

[gas4you]

Standard water supply is 25mm alcathene that then connects to 22mm copper at the internal stop cock.

20mm ie for connecting to 15mm copper. You need a 22mm supply for an unvented cylinder.

 

[chrishutt]

For 2 baths and 4 showers from a 300 litre unvented cylinder even 25mm may be inadequate. Go for 32mm. If you liaise with the Water Company they may upgrade their supply pipe from the main to your boundary free of charge and to the same standard (32mm) under a lead replacement scheme.

There is no advantage in using smaller pipe, only disadvantages. A professional would understand this. Does the "plumber" who installed the unvented cylinder have an "unvented ticket" (an identity card showing that he has undertaken the appropriate training and assessment)?

 

[smudger29]

Indeed the input to the tank is 22mm but should I be insisting on a larger dia feed pipe to the internal stop cock. Right now there is 20mm stuff lying in the trench due to be connected up on Tuesday should I be insisting on 32mm to give sufficient flow for 4 showers? And is there anyting negative about going larger dia?

Sorry to be so dim - I don't want to get fobbed off by my builder but at the same time need to know the facts So I can argue for what I need.

The pipe run to the House is around 25m

Thanks again for the advice - appreciate it

 

[chrishutt]

should I be insisting on a larger dia feed pipe to the internal stop cock?
should I be insisting on 32mm?
is there anyting negative about going larger dia?

I don't know how many times you need to be told this. I said it twice, others have said it too, but you still don't get it.

 

[gas4you]

I agree with Chris, why can you not take our advice that you came on here to get

If you go with the 32mm that chris suggests you will be covered for all eventualities.

Insist your builders cowboy plumber changes that 20mm pipe. You will regret it a hell of a lot later.

You shouldn't have to pay for the change either, as a competent plumber would know you need a bigger supply than this. Is the cowboy G3 registered? I doubt it.

I'm only a gas heating engineer who is G3 rated, but I think I know more about plumbing than this idiot.

Where does this builder and plumber live? On the local gypo's site

 

[Balenza]

smudger29 wrote

should I be insisting on 32mm to give sufficient flow for 4 showers?

Id stick with the 20mm. (even though your 4 showers run consecutively will probably be a dribble)
It will conserve water which is obviously what your plumber is thinking off and that can't be a bad thing with such a precious commodity.

a 3 hundred litre unvented hot water system

Incidentally have you seen this ?.
http://www.waterheaterblast.com/

Its what they do when they go wrong or are installed incorrectly.
Yes a BOMB and an extremely powerful one. And your allowing a cowboy to install one in your home.

 

[smudger29]

thankyou all for your advice - the plumber is qualified to fit unvented hot water systems so hopefully I won't be exploding - I'll ask why 32mm has not been used.

 

[chrishutt]

the plumber is qualified to fit unvented hot water systems ...

So you've seen his identity card confirming this?

 

[Agile]

thankyou all for your advice - the plumber is qualified to fit unvented hot water systems so hopefully I won't be exploding - I'll ask why 32mm has not been used.

Dont just ask him you have to TELL him that you wil not accept anything less than 32 mm in the trench.

Dont pay him unless he has fitted 32 mm.

Tony