Plumbing; home run / Traditional hybrid?

[junglejim]

I’m currently planning my hot and cold water layout. I like the idea of the ‘home run’ setup with pex runs from a central manifold. Its a lot of pipe though and I’m thinking a smart spring might be to zone the house and run zones from the manifold then tee off from the zone to the appliances.

 

my logic for home run is that we’re doing timber frame build and I don’t want joints in inaccessible locations.

 

The home run setup doesn’t seem so common in the uk as it does in Europe so wondering what folks think? 
 

thanks
 

 

[JohnMo]

Never heard it called home run before.

 

But plenty on here use a manifold system. Two ways really, each user gets it's own manifold outlet with isolation valve or slightly simpler each wet room gets it's own manifold outlet and isolation valve, the tee off in room.

 

But don't go any larger than 15mm for either layout mentioned. 

 

I took my cold runs under the insulation within a concrete slab, nice cool water to taps all year. Hot I ran through the ceiling insulation.

 

[Russell griffiths]

Why are you worried about it using a lot of pipe, pipe is cheap, fittings not so. 
3-4 rolls of 50m will see it all done. 

[Oz07]

4 hours ago, JohnMo said:

Never heard it called home run before.

 

But plenty on here use a manifold system. Two ways really, each user gets it's own manifold outlet with isolation valve or slightly simpler each wet room gets it's own manifold outlet and isolation valve, the tee off in room.

 

But don't go any larger than 15mm for either layout mentioned. 

 

I took my cold runs under the insulation within a concrete slab, nice cool water to taps all year. Hot I ran through the ceiling insulation.

 

Do you not have to worry about freezing?

[Oz07]

I've done manifold before to each appliance. Good for maintenance purposes. Also meant I could run the pipework whereas I wouldn't be confident doing all the fittings. 

[JohnMo]

33 minutes ago, Oz07 said:

Do you not have to worry about freezing?

We get -9, no issues. Pretty well protected from the elements, ground under the house is around 6 degs.

[Iceverge]

Run 10mm Hep2O pipe for everything except the cold kitchen/utility taps, outdoor taps and hot+cold bath and showers feeds. 

 

Heat the hot manifold by convection by having it just above the outlet of the UVC. 

 

Don't bother with pipe insulation outside the plant room. It makes no difference. 

 

I assume home run is having all pipes directly individually leading from your manifold to the destination. One pipe to one outlet? 

 

 

Edited 13 hours ago by Iceverge

[Thorfun]

53 minutes ago, Iceverge said:

Run 10mm Hep2O pipe for everything except the cold kitchen/utility taps, outdoor taps and hot+cold bath and showers feeds. 

I ran 15mm everywhere from my central manifolds. I was just a little worried about flow rate for the 10mm plastic pipe. 
 

10 hours ago, JohnMo said:

But plenty on here use a manifold system. Two ways really, each user gets it's own manifold outlet with isolation valve or slightly simpler each wet room gets it's own manifold outlet and isolation valve, the tee off in room.

Option 1 for me. Every tap/outlet has its own pipe. One major benefit is no pressure drop when other outlets are being used and you don’t get scalded or frozen when another tap is used or a toilet flushed!!

 

plus it looks really cool in the plant room for showing off your plumbing prowess. 🤣

[Oz07]

10 hours ago, JohnMo said:

We get -9, no issues. Pretty well protected from the elements, ground under the house is around 6 degs.

Good to know. Other half wants an island in new place and with ufh you'd be getting lukewarm out the tap. How deep did you go or literally just below insulation?

[JohnMo]

53 minutes ago, Oz07 said:

How deep did you go or literally just below insulation?

Our floor has a 200mm thick concrete slab below the insulation, the pipes were zip tied to rebar in that. So about about 400mm below finished floor level 

[JohnMo]

6 hours ago, Thorfun said:

One major benefit is no pressure drop when other outlets are being used and you don’t get scalded or frozen when another tap is used or a toilet flushed!!

You don't get that option 2 either 

[Nickfromwales]

5 minutes ago, JohnMo said:

Our floor has a 200mm thick concrete slab below the insulation, the pipes were zip tied to rebar in that. So about about 400mm below finished floor level 

So never subject to / at risk from

freezing at all. Did you sleeve them?

[Nickfromwales]

6 hours ago, Thorfun said:

One major benefit is no pressure drop when other outlets are being used and you don’t get scalded or frozen when another tap is used or a toilet flushed!!

That’s mostly just down to using good quality thermostatic showers vs ‘manual’ mixers. Decent ones will work with quite erratic flows and temps, so I always advise my clients to spend some money on such daily drivers. 

[Oz07]

5 minutes ago, Nickfromwales said:

So never subject to / at risk from

freezing at all. Did you sleeve them?

Why isn't it at risk if below insulation?

[Nickfromwales]

Just now, Oz07 said:

Why isn't it at risk if below insulation?

Geothermal heat / mass doesn’t swing temps below ground like it does in the frost layer (0-300mm iirc) at ground level.

 

That’s how GSHP’s can give heat out when there’s snow on the ground. 

[Nickfromwales]

Note: At those depths WRAS regs would bother me a lot more; they want a duct so the pipes can be withdrawn / replaced.

 

I’m happy running pipes above a constructional, uninsulated slab, in standard pipe insulation, but this is a bit extreme for installing domestic pipework, naked, imo.

 

[JohnMo]

25 minutes ago, Nickfromwales said:

So never subject to / at risk from

freezing at all. Did you sleeve them?

Yes they are in conduit, so could replace in theory if I needed too.

[Oz07]

2 hours ago, Nickfromwales said:

Note: At those depths WRAS regs would bother me a lot more; they want a duct so the pipes can be withdrawn / replaced.

 

I’m happy running pipes above a constructional, uninsulated slab, in standard pipe insulation, but this is a bit extreme for installing domestic pipework, naked, imo.

 

What about below slab and insulation in flexible duct/conduit. Id imagine the ground under a floorslab doesn't get as cold as the ground outside your house ie below patio

[ProDave]

What you want to avoid is long HOT runs from your tank to the taps (unless you are having hot water recirculation which is another discussion)

 

So I chose my layout based on that.  HW tank central to points of use.  That made it nice and simple.  One direct WH run from the tank to the kitchen.  No manifold, just an isolator at the HW tank.

 

The rest of the HW taps were the opposite direction, so I ran one pipe to a manifold under the first floor below the main bathroom, accessed by a small trap door in the utility room ceiling below it.  There is a a manifold to feed basin, showerand bath  for main bathroom, basin and shower for en-suite and basin for utility room.

 

Cold you can do what you like, length of runs does not really matter.

 

All soldered copper, I trust my soldering.