Advice on plumbing a new house

gwebstech · 18 Jan 2020

Hi all

Ive done a fair bit of plumbing in the past - re routing pipes, installing new rads, bathrooms etc but these were all on older houses where for example there was a flow to the rads, then the outlet went to the next rad etc

Ive now got a new house to plumb, and i understand that a more modern type of system has a 22mm flow and branch off to each rad, and a similar thing for the return?

So im considering using microbore, so the pipes can be hidden behind the plasterboard but is this the best way to plumb a new house and do i need to use manifolds if doing this?

Also id prefer to use copper where i can but the joists mean ill have to use some plastic 22mm for feed and return

thanks for any advice

Nozzle · 18 Jan 2020

Or you could consider a manifold and a pair of pipes to each radiator.

oldbutnotdead · 18 Jan 2020

Depends on your definition of 'best' and the layout of your house.
Easiest and quickest will be accessible manifolds and pairs of plastic going to each rad.

gwebstech · 18 Jan 2020

Nozzle said:
Or you could consider a manifold and a pair of pipes to each radiator.

arent manifolds only in blocks that do 4s?

gwebstech · 18 Jan 2020

oldbutnotdead said:
Depends on your definition of 'best' and the layout of your house.
Easiest and quickest will be accessible manifolds and pairs of plastic going to each rad.

Regarding the layout, seeing as its all new i can pretty much make the pipes go wherever is best and by best i mean in terms of working optimally

so theres no issue with needing a water softener as i read not all boilers allow them for warranty purposes?

thanks

oldbutnotdead · 18 Jan 2020

Optimal (depending on the size of the house but unless you've got a mansion normal sizes will work) might be a trunk network of 22mm from boiler to each floor then 2 manifolds on each floor (feed and return) where your radiator tubes run from.
What are your hot water plans-combi, vented, unvented, plate hex?
No idea why you'd use a water softener in a heating system, just dose it with inhibitor like everyone else. No clue on boiler warranties either

Nozzle · 18 Jan 2020

You should fill your primary side from town water with inhibitor, not softened water

Nozzle

Madrab · 18 Jan 2020

How many radiators, I take it they'll be smaller given it's a new house with higher levels of insulation? If it's a larger system, even if not, I'd advise no smaller than 15mm, longer term 10mm can be a pain in the ass, especially in a larger system when it inevitably furs up and resistance increases. I have 10mm copper in mine, 16 med sized rads (3 are larger), it's around 15/20years old (wasn't me, I moved in about 8 yrs ago) and I'm now starting to get slower heat up times, no matter how I balance/set it up, pump's getting noisy again, it's does limit the size of rad that can be used in the larger living room, no easiest to clean etc.

I'll be going to UFH and a centralised layout later this year. If I wasn't though I'd be ditching the 10mm and dropping in 15mm feeds, which i still might have to do in the loft anyway.

Ryler · 19 Jan 2020

gwebstech said:
Ive now got a new house to plumb

Is it...
New build bungalow (block wall cavity)
New build two storey (block wall cavity)

Timber frame bungalow
Timber frame two storey
?

Or is it just a new house to you?
And been built for a long time.

gwebstech · 19 Jan 2020

Thanks for the replies guys

Its a brand new 4 bed house, 100mm cavity wall, approx 14 rads, combi boiler

the thing about the water softener was thats its a hrd water area and id read something about needing to treat the hard water if using microbore

and one of the main reasons i was going to use microbore is that i thought it was used in all new homes and that hiding 15mm pipes behind walls isnt ideal

cheers

Ryler · 19 Jan 2020

The way I've done it before is lay all the pipes on the sub floor. Smallest being 15mm.
Then insulation, then final screed.
All copper pipe and end feed, I've done brazing and soldering. All pressure tested before screed laying. Its the method that uses the least amount of pipe work.
And provides the best joint.

gwebstech · 19 Jan 2020

Ryler said:
The way I've done it before is lay all the pipes on the sub floor. Smallest being 15mm.
Then insulation, then final screed.
All copper pipe and end feed, I've done brazing and soldering. All pressure tested before screed laying. Its the method that uses the least amount of pipe work.
And provides the best joint.

You used UFH all across the downstairs? how has it fared over the years?

and you think this is better than the electrical wire type?

Ryler · 19 Jan 2020

gwebstech said:
You used UFH all across the downstairs?

Only did two ufh installations. About 16 years ago. On two large properties.
Never been any problems. pex pipe

oldbutnotdead · 19 Jan 2020

Solid floors downstairs then? Don't know where you're getting your ideas from (softener and microbore).
15mm in walls is fine and will be longterm more reliable and give better heat performance than smaller tube.
Only 1 bathroom then (or does the combi have oversized dhw capacity)
Professionals often do things not because its the best way to do it but because its the cheapest. For instance, the big housebuilders will get massive discounts on materials so what is cost-effective for them (deskill most of the installation by getting the apprentice to throw 300 m of tube into the walls) doesn't necessarily work for you.
You sound as if you're looking at details very early in the process- have you done heat loss calcs, have you decided where you want radiators in the rooms?

gwebstech · 19 Jan 2020

oldbutnotdead said:
Solid floors downstairs then? Don't know where you're getting your ideas from (softener and microbore).
15mm in walls is fine and will be longterm more reliable and give better heat performance than smaller tube.
Only 1 bathroom then (or does the combi have oversized dhw capacity)
Professionals often do things not because its the best way to do it but because its the cheapest. For instance, the big housebuilders will get massive discounts on materials so what is cost-effective for them (deskill most of the installation by getting the apprentice to throw 300 m of tube into the walls) doesn't necessarily work for you.
You sound as if you're looking at details very early in the process- have you done heat loss calcs, have you decided where you want radiators in the rooms?

i was just thinking that the socket backboxes will take as much room as 15mm pipe anyway and yes concrete floors downstairs. There will be an ensuite but i know that boiler wont power both showers at once so im not sure whether to put an electric shower over the bath or not. The roof has just been covered so 1st fixing next stage, ive not done nay heat loss calcs yet but isnt that the job of the energy calc guys who wil ldo it for the building regs?

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Advice on plumbing a new house

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