Water pressure

[zad3717]

So finally we have the go ahead for our extension… and I’m after some advice on plumbing! Currently have a 4 bed 1 bath with rubbish pressure on a 32kw combi boiler.

it will be a 6 bed 3 bath when extension is done, boiler is only 6 years old so need advice on what to go for.

keep boiler and add S plan?
New larger boiler
New larger boiler with storage
System boiler with storage

my main concern is the pressure will still be the same coming in this going out…. Is it worth adding a mains pressure booster? Do they work,

any advice, experiences welcome

thanks

 

[bernardgreen]

Hot water storage cylinder(s) and a heat only boiler.

 

[Swwils]

32kw boiler is likely massively oversized.

 

[CBW]

I’m glad you’ve asked here and not whoever recommended a 32Kw Combi with poor pressure. As stated a heat only with cylinder. I don’t think a mains boost is your answer.

 

[zad3717]

The boiler is already in? It’s 6 years old. and as the boiler is relatively young not worth utilising it?

the pressure issue is the cold feed in it’s rubbish… so any experience with mains pressure boosters? Like https://www.plumbworld.co.uk/stuart...rifugal-pressure-set-pump-44622-19703-1253840

 

[Jajodu]

A large vented hot water tank, a cold feed tank in the loft, a Stuart Turner 3 bar pump and y plan valve. That will give you loads of hot water and the pump will give excellent showers. Keep the boiler just don't use the hot water side of it.

 

[JohnD]

How much flow do you get?

What is the size and age of the incoming water supply pipe?

Have you measured the pressure? It is not the same as flow.

 

[zad3717]

How much flow do you get?

What is the size and age of the incoming water supply pipe?

Have you measured the pressure? It is not the same as flow.

It’s not lead, and house was built 1971…

flow rate in the area is notorious for being rubbish, some days it’s worse than others but speak with UU and they say it’s fine and with in their tolerance… all the new builds around us are fine guessing they have new mains…

 

[JohnD]

So when you fill a bucket and time it, how many litres per minute do you get?

 

[Madrab]

What are the mains dynamic pressure and flow rate? Both those figures and needed before any advise could be suggested.

That and if you want 2/3 or more HW outlets running at the same time then a combi will never cut it.

Mains boosters will only supply 12L/Min max @ ~ 1.5 bar'ish

 

[oldbutnotdead]

It’s not lead, and house was built 1971…

flow rate in the area is notorious for being rubbish, some days it’s worse than others but speak with UU and they say it’s fine and with in their tolerance… all the new builds around us are fine guessing they have new mains…

With 3 bathrooms some sort of hot (and cold) water storage is the only way forward. Your water provider is obliged to provide 10 litres per minute at 1 bar, long as they're doing that you have no right to better. As above, big tank, big cylinder, 3 bar pump and you'll be laughing.
Your combi was probably not the right solution 6 years ago (given low pressure/flow) but lots of boiler slingers push combi boilers at every scenario.

 

[JohnD]

It’s not lead, and house was built 1971…

Do you mean it's black plastic?

What size?

 

[zad3717]

Do you mean it's black plastic?

What size?

Yes alcathene, and not sure probably 18mm -20mm

 

[zad3717]

So when you fill a bucket and time it, how many litres per minute do you get?

Do I do this at the nearest or furthest cold tap…

 

[JohnD]

Yes alcathene, and not sure probably 18mm -20mm

Probably half-inch internal bore then. You will benefit from bigger.

Are the pipes inside the house 15mm copper?

Start with the kitchen sink cold tap, and the garden or utility room if you have them.

I expect the hot taps will be a bit less.