Starting first Fix - Manifolds and pipe types etc

[Conor]

Starting my plumbing very soon and figuring out the design. From this wonderful forum, this is what I'm thinking:

 

(300l UVC setup with ASHP, good mains pressure around 4bar, 32mm supply to the building)

 

• Hot and cold water manifolds - 22mm supplies.
• One pipe per outlet or one pipe (H&C) for each room? E.g. for a WC pipe for the cold wash basin and separate for the toilet or tee off?
• 10mm pipes are preferred for frequently used hot water outlets. Should I use 10mm for everything except showers and baths?
• Insulate hot water pipes - I can only get 16mm pre-insulated pipes locally. Is it a pain to lag pipes?
• Three story building - one set of manifolds in the basement or a separate one for the top floor?
• Pipe types. Pipe Life PEX pipe is the best value (10mm Qualpex). Is this the right pipe for the job or is something like this barrier pipe better? I don't see the difference....

 

This should get me started for now... I'm not worrying too much about the heating side just yet, just want to start bunging pipes in!

[pdf27]

Is there any benefit to lagging pipes from cylinder to point of use? If it's 10mm the amount of energy lost in just letting it cool down should be pretty trivial unless you've got very long runs. The primary circuit from ASHP to UVC does definitely need lagging though.

[Conor]

2 minutes ago, pdf27 said:

Is there any benefit to lagging pipes from cylinder to point of use? If it's 10mm the amount of energy lost in just letting it cool down should be pretty trivial unless you've got very long runs. The primary circuit from ASHP to UVC does definitely need lagging though.

I thought it was a BC requirement?

[LA3222]

40 minutes ago, Conor said:

Starting my plumbing very soon and figuring out the design. From this wonderful forum, this is what I'm thinking:

 

(300l UVC setup with ASHP, good mains pressure around 4bar, 32mm supply to the building)

 

• Hot and cold water manifolds - 22mm supplies.
• One pipe per outlet or one pipe (H&C) for each room? E.g. for a WC pipe for the cold wash basin and separate for the toilet or tee off?
• 10mm pipes are preferred for frequently used hot water outlets. Should I use 10mm for everything except showers and baths?
• Insulate hot water pipes - I can only get 16mm pre-insulated pipes locally. Is it a pain to lag pipes?
• Three story building - one set of manifolds in the basement or a separate one for the top floor?
• Pipe types. Pipe Life PEX pipe is the best value (10mm Qualpex). Is this the right pipe for the job or is something like this barrier pipe better? I don't see the difference....

 

This should get me started for now... I'm not worrying too much about the heating side just yet, just want to start bunging pipes in!

I'm doing bits and bobs of various things at the minute one of which is to run all the pipes in the next couple of days.

 

I'm doing manifold in plant room, one set for cold, one set for hot, one set for hot return. Using 15mm Hep for the big hots/colds like shower bath sink, 10mm for all other hots/cold.

 

I'm insulating everything, hot and cold. Bought a load of armaflex in 35m coils. I'll just have to slip it over the pipes as I go - won't be the worst job I've done.

 

22mm copper to the manifolds, plastic out. Just running pipes for now so sparky can then first fix. I've got a floor deck to lay over my first floor ufh then I'll be on the plumbing again. 300l UVC and ASHP should be here by end of April at latest.

[pdf27]

The only bit I can find is:

Note that primary pipes are those between the heat source (ASHP in your case) and the hot water cylinder - lagging these is a good idea anyway, as is keeping them as short as you can. Pipes from the hot water cylinder to the point of use are secondary ones. The reality is that unless you use the secondary pipes very frequently they will have cooled down before the next use no matter how well lagged they are.

The one exception to this is if you are running a secondary return hot water system because the hot water cylinder is a long way from the point of use - if you are, then the pumped circuit absolutely needs to be well insulated since being shared across a large number of draw-off points means it will be running far more frequently and will be kept hot to minimise draw-off time.

[pdf27]

Digging further, looks like you're supposed to insulate them for 1m away from the cylinder if it's heated by a gas boiler:

There isn't any equivalent guidance for heat pump systems - I would just insulate the 22mm pipe from the cylinder the the manifold since that pipe will be seeing far more frequent draw-offs so would probably benefit from it.

 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/697525/DBSCG_secure.pdf

Edited March 23, 2021 by pdf27

[Conor]

Thanks all, very useful.

 

I'll not worry about insulation then.

 

So 10mm is fine to sink outlets then? That'll make things a bit easier and cheaper.

[dpmiller]

the 10mm works fine, as a data point we've more DHW flow at the new place at the end of 10m of 10mm @3bar, than the gravity flow down half that length if 22/15mm at the current house.

[Conor]

Can I get your thoughts on this @Nickfromwales please?! 

 

Is 10mm throughout the best option for hot and cold outlets? And one pipe per outlet? I'm thinking 15mm of larger outlets like showers and baths? I think we have 3-4bar mains pressure here.

 

Thanks! 

[Nickfromwales]

6 minutes ago, Conor said:

Can I get your thoughts on this @Nickfromwales please?! 

 

Is 10mm throughout the best option for hot and cold outlets? And one pipe per outlet? I'm thinking 15mm of larger outlets like showers and baths? I think we have 3-4bar mains pressure here.

 

Thanks! 

15 to baths and showers, deffo, and 10mm hot and cold to basins is plenty. Most basin taps have flow restriction by design / regs, so pointless giving much more unless they’re very long, convoluted runs. 
Sinks ( kitchen and utility ) I’d typically do a much x 10mm hot feeds and 15mm cold feeds and attach the appliances to the 15mm colds that service the sinks.

Topology affects this basic go-to plan of course and there is never a one-stop answer / solution. 
Introducing a HRC for long hot runs affects things further. 

[joe90]

I have used 10mm to basins hot and cold and the water supply is more than sufficient and the hot water is there in seconds and little losses etc . 15mm to showers, bath and kitchen sink. I only lagged 22mm DHW tank to manifold (regs are 1m I believe). I would not change anything if I did it again.

Edited April 27, 2021 by joe90

[andy]

Having finished mine off recently, I would definitely:

 

• 22mm hot and cold manifold.
• Isolated feed to all outlets from there - I went 22mm to 1 shower and bath and 15mm to everything else but that was cos I didn't have 10mm, probably makes sense to where flow not needed.
• Armaflex lagged everything - I used the self-sealing split stuff, really good but does need taping too where you go round corners.   Probably overkill and took ages but hey, it's done now
• Continuous runs of Hep2O from manifold to outlet (or very close) - no way I would do anything different or use any other pipe.  Absolute no brainer I feel here.
• Long 28mm runs to/from ASHP - due to circumstances these were needed but hell to work with, definitely design out if possible in future...

Think that's the main bits from my recent adventures in plumbing.

[Conor]

Thanks everybody.

 

10mm hot and cold pipes to all WCs and basins

15mm to showers/baths and kitchen sink. 

Tee off in kitchen and utility for appliances, boiling water tap etc.

22mm supplies to the manifolds / UVC.

 

At a quick count that means approx 30 individual pipes. I've not seen anything bigger than a 4 port manifold. Do you have to make your own from 22x15mm / 22x10mm tees?!

 

 

 

 

 

 

 

 

 

 

 

Edited April 27, 2021 by Conor

[joe90]

You can make your own from copper but I used a few of these https://www.screwfix.com/p/hep2o-plastic-push-fit-reducing-4-port-closed-spigot-manifold-22-x-10mm/2901R?tc BEWARE, you can connect them together but can’t get the remount tool in to get them apart, ask me how I know ?, also I did not have individual shut off valves on each run, just a 1/4 turn isolator on the 22mm feeds into the manifold. How often would you need to isolate a single feed for any length of time? I did tee two toilets rather than buy another manifold, the bottom tee is to a drain tap.

Edited April 27, 2021 by joe90

[Nickfromwales]

15mm cold at the kitchen sink should be hard water, rest of house softened if you’re in a hard water area. The rule for taking appliances alters at the kitchen sink to suit circumstance, so you may need both a hard and a soft cold feed at the kitchen sink.

Typically;

15 soft at utility sink to feed washing machine. 
15mm soft at kitchen sink to feed dishwasher.

15mm hard to kitchen sink cold outlet plus any boiling tap / other device which have their own water ‘conditioner’ but don’t take softened water. 
Simples!

[Conor]

We're soft water so no issues there.

[Nickfromwales]

Happy days. Much less of a ball ache ?

[Conor]

1 hour ago, joe90 said:

You can make your own from copper but I used a few of these https://www.screwfix.com/p/hep2o-plastic-push-fit-reducing-4-port-closed-spigot-manifold-22-x-10mm/2901R?tc BEWARE, you can connect them together but can’t get the remount tool in to get them apart, ask me how I know ?, also I did not have individual shut off valves on each run, just a 1/4 turn isolator on the 22mm feeds into the manifold. How often would you need to isolate a single feed for any length of time? I did tee two toilets rather than buy another manifold, the bottom tee is to a drain tap.

 

So even though it's a closed spigot, I presume you can trim the end off and connected it up to JG coupler/bend/tee etc? I see what you mean about not being able to demount... think I'd stick in a coupler and a short section of pipe.