Cold water manifold, how big is toooo big

[Russell griffiths]

Evening, just planning out all my hot and cold points around the house. 

I plan to use a manifold distribution system and if I run a singular pipe to all points in the house I end up with 16 ports needed on the cold manifold, now I can reduce this by having a couple of toilets teed from a basin pipe, or is 16 a nice happy number and I should just carry on. 

 

I have a big long wall to put the manifold on so that’s not an issue. 

[PeterW]

Toilets tend to have built in isolators so I just run direct to them. 

[LA3222]

Can't see why 16 would be an issue.....configure it as two banks of 8 so its not one great long line? I expect I'll be at a similar no. to what you jave.

[Pocster]

Bigger is best ! 

[Thorfun]

not being a plumber but being very interested in learning, what's the benefit of having a manifold like that rather than some other system? is there even another way of doing it? would this be implemented where the water supply enters the building or can you run a big pipe from where the supply enters to another location in the house and in to the manifold for distribution?

 

sorry for the noddy questions, I've not really started investigating plumbing yet!

[Pocster]

9 minutes ago, Thorfun said:

not being a plumber but being very interested in learning, what's the benefit of having a manifold like that rather than some other system? is there even another way of doing it? would this be implemented where the water supply enters the building or can you run a big pipe from where the supply enters to another location in the house and in to the manifold for distribution?

 

sorry for the noddy questions, I've not really started investigating plumbing yet!

It means I can isolate any single thing easily . Essentially there is a seperate cold and hot water pipe to everything . It means no joints . But more pipe and not fun to thread all of it through . I’ve done exactly the same with wiring . So a radial lighting cable and socket cable to each room . For diy ‘er this makes sense ?

[PeterW]

@Thorfun Can run a 22 or 28mm supply to the plant room and then into the UVC Control block, taking the cold off as a balanced cold supply. 
 

From there you go to the hot and cold manifolds and then off in 15 or 10mm pipe to each outlet.
 

You can run a standard loop from the balanced cold and the UVC hot with 22mm and tee off to each location with 15mm which is how it used to be done. Nothing wrong with that, you just end up isolating at point of use rather than supply. 

[Thorfun]

ok, thanks guys. I think I understand both methods now. I believe that every house I've ever lived in has had it the way @PeterW mentions as a standard loop (probably why it takes ages for the hot taps to get hot water!). but, even though it's more pipe I really like the idea of having a centralised location for all the pipes to that you can isolate them at one place. I've a feeling that if I get a professional to do the plumbing that they'd go for the standard loop way as it's easier and cheaper on materials and time!

[redtop]

7 minutes ago, Thorfun said:

ok, thanks guys. I think I understand both methods now. I believe that every house I've ever lived in has had it the way @PeterW mentions as a standard loop (probably why it takes ages for the hot taps to get hot water!). but, even though it's more pipe I really like the idea of having a centralised location for all the pipes to that you can isolate them at one place. I've a feeling that if I get a professional to do the plumbing that they'd go for the standard loop way as it's easier and cheaper on materials and time!

Ime doing it this way, one manifold, and one big benefit for me is I can run each pipe as I get round to that part of the build. Makes sense if self building and living in it as we go!

[Thorfun]

5 minutes ago, redtop said:

Ime doing it this way, one manifold, and one big benefit for me is I can run each pipe as I get round to that part of the build. Makes sense if self building and living in it as we go!

indeed it does. also ties in with my requirement to centralise my lighting system as well. have everything branch out from the plant/comms room.

 

seems so very logical to my mind.

 

ps. sorry to @Russell griffiths for hijacking your thread! ?

Edited October 28, 2020 by Thorfun

[PeterW]

Just as an advisory to those who do go manifold for the ease of isolating individual circuits - always cap the open end of the pipe at the point at which you terminate it, you will at some point turn the wrong isolator ...... 

[Pocster]

12 minutes ago, PeterW said:

Just as an advisory to those who do go manifold for the ease of isolating individual circuits - always cap the open end of the pipe at the point at which you terminate it, you will at some point turn the wrong isolator ...... 

Already capped ?

[SuperJohnG]

I don't really see the added value here. It's just more pipework, costs and labour doing this IMO.  

 

I get the perceived benefit of having a central location to isolate anything. But in reality how often is anyone isolating anything, hardly ever. Once you are connected and no leaks, unless you need to change something out you don't isolate it, then even if you have to  theres a local isolation valve or the mains can just be isolated. 

[Oz07]

Major benefit which you are forgetting @SuperJohnG is elimination of joints within the structure of the building. Ever piece of pipe is a full run with only joints at either end. Also whatever the technical term is but I can flush loo and it doesn't affect shower when running. 

[Nickfromwales]

6 hours ago, SuperJohnG said:

I don't really see the added value here. It's just more pipework, costs and labour doing this IMO.  

 

I get the perceived benefit of having a central location to isolate anything. But in reality how often is anyone isolating anything, hardly ever. Once you are connected and no leaks, unless you need to change something out you don't isolate it, then even if you have to  theres a local isolation valve or the mains can just be isolated. 

If the OP has 16 x cold feeds ( assuming 3 x WC’s / 2 x cold mains appliances ) that’s 11 outlets requiring cold supplies ( so also assuming 11 hot supplies ) then the cold supply would need to get to at least the first two bathrooms in a minimum poor size of 22mm. Same for the hot, but the hot more like starting off in 28mm, then picking up the first bathroom, and then 22mm from there forward, and then reducing to 15mm as seen fit. Really if a bathroom is the last item then you can’t drop to 15mm until you’ve picked up the shower & bath. 
So, a minimum of 26 x T connections if you don’t adopt a radial manifold setup and fingers crossed after you’ve tested initially and boarded up. 
Another benefit is that for a new / self builder, you can just bring on items as work progresses, so no need to keep draining down / connecting / re-pressurising each time you add a new item. 
And, the party piece is hot return and flow rates. With a large single bore series setup you’ll be waiting for a very long time to get hot water out of basin sinks in particular as they are low flow / high frequency use and by the time hot had got there you’d have got fed up waiting. Pressure and flow rates are as uniform as you can get too, so question has to be.....why wouldn’t you do it? 
Not having isolations on the end of every run / at each outlet is a no-brainer, as most modern bathrooms won’t have somewhere for such valves to be easily / practically accessed, particularly for baths and showers etc. 

Regular ( series ) 0
Manifold ( radial ) 1 ( well 4 actually ). 

[Nickfromwales]

13 hours ago, Russell griffiths said:

Evening, just planning out all my hot and cold points around the house. 

I plan to use a manifold distribution system and if I run a singular pipe to all points in the house I end up with 16 ports needed on the cold manifold, now I can reduce this by having a couple of toilets teed from a basin pipe, or is 16 a nice happy number and I should just carry on. 

 

I have a big long wall to put the manifold on so that’s not an issue. 

Don’t be scared about having a big one   Will suit your build timelines perfectly with you being able to connect and test over time / as you go. ?

[Pocster]

18 minutes ago, Nickfromwales said:

Don’t be scared about having a big one   Will suit your build timelines perfectly with you being able to connect and test over time / as you go. ?

I certainly have a BIG one ??

[Thorfun]

4 hours ago, Nickfromwales said:

If the OP has 16 x cold feeds ( assuming 3 x WC’s / 2 x cold mains appliances ) that’s 11 outlets requiring cold supplies ( so also assuming 11 hot supplies ) then the cold supply would need to get to at least the first two bathrooms in a minimum poor size of 22mm. Same for the hot, but the hot more like starting off in 28mm, then picking up the first bathroom, and then 22mm from there forward, and then reducing to 15mm as seen fit. Really if a bathroom is the last item then you can’t drop to 15mm until you’ve picked up the shower & bath. 
So, a minimum of 26 x T connections if you don’t adopt a radial manifold setup and fingers crossed after you’ve tested initially and boarded up. 
Another benefit is that for a new / self builder, you can just bring on items as work progresses, so no need to keep draining down / connecting / re-pressurising each time you add a new item. 
And, the party piece is hot return and flow rates. With a large single bore series setup you’ll be waiting for a very long time to get hot water out of basin sinks in particular as they are low flow / high frequency use and by the time hot had got there you’d have got fed up waiting. Pressure and flow rates are as uniform as you can get too, so question has to be.....why wouldn’t you do it? 
Not having isolations on the end of every run / at each outlet is a no-brainer, as most modern bathrooms won’t have somewhere for such valves to be easily / practically accessed, particularly for baths and showers etc. 

Regular ( series ) 0
Manifold ( radial ) 1 ( well 4 actually ). 

 

@Nickfromwales. is this how you plumb your customer's sites? or do you give them the option of either way as I presume the manifold way is more expensive on labour and materials?

[ProDave]

12 hours ago, SuperJohnG said:

I don't really see the added value here. It's just more pipework, costs and labour doing this IMO.  

 

I get the perceived benefit of having a central location to isolate anything. But in reality how often is anyone isolating anything, hardly ever. Once you are connected and no leaks, unless you need to change something out you don't isolate it, then even if you have to  theres a local isolation valve or the mains can just be isolated. 

I did a halfway house.

 

Kitchen and utility each have their own feeds with local isolators.

 

Where I used a "manifold" was for the 2 adjacent bathrooms.  This gives me isolation for each in one place.  And to keep pipework runs short, particularly hot water, the manifold is placed under the floor of the main bathroom accessed through a small trap door in the ceiling of the utility room.

 

to save cost I "made my own"

 

[Nickfromwales]

21 minutes ago, Thorfun said:

 

@Nickfromwales. is this how you plumb your customer's sites? or do you give them the option of either way as I presume the manifold way is more expensive on labour and materials?

Every sizeable dwelling gets this discipline installed as standard. 
I never leave specifications to a client tbh. I make them aware ( at the quote stage usually ) of what will be installed and why. 
I don’t get into that degree of being micro-managed as people are asking for my professional opinion vs them wanting to go to a cheaper option due to bean counting. 
Clients could demand that I do it a certain way and I can then either cover myself with signed caveats, or refuse to do the job, particularly if I felt that was going to be more laborious for me ( what bean counters often decide to selectively overlook ) or to the detriment of the finished system and its reliable ( and robust ) operation.
Hepworth manifolds have a good waterway and allow flow through with relative silence, but cheaper ball valves / other isolators can be both restrictive and noisy by comparison. 
 

For @Russell griffiths job I’d be feeding both ends of the manifold with water, so a bit like a ring.

Costs aren’t a million miles away from ‘normal’ plumbing when you discount all the joints, costs of additional fittings, increased liabilities and the number of times you’ll have to drain down and refill during the course of an entire build. 
 

Ive had such good results with the manifold system why do anything else? “Tried and tested”. Members here with the traditional arrangement have given poor feedback on the amount of time it takes to get hot water out of the taps with the primary distribution having been in 22mm everywhere, or even worse, starting in 28mm  

?. Not for me sir, no thanks. 

[joe90]

+1 fir manifolds but not necessarily isolators on every one (except where partial completion requires it). I isolate the feed pipes into the manifolds (one hot and one cold) this will suffice for mending taps etc. I also ran hot to basins in 10mm which speeds up hot water getting there a lot and gives more than sufficient volume.

[Nickfromwales]

Just now, joe90 said:

+1 fir manifolds but not necessarily isolators on every one (except where partial completion requires it). I isolate the feed pipes into the manifolds (one hot and one cold) this will suffice for mending taps etc. I also ran hot to basins in 10mm which speeds up hot water getting there a lot and gives more than sufficient volume.

Yup, the 10mm works surprisingly well. 

[Pocster]

5 minutes ago, Nickfromwales said:

Yup, the 10mm works surprisingly well. 

Now I’m sure everyone told me 15mm min !! ?

[Nickfromwales]

9 minutes ago, pocster said:

Now I’m sure everyone told me 15mm min !! ?

No two cases the same. Depends on distances etc. 

[Pocster]

Just now, Nickfromwales said:

No two cases the same. Depends on distances etc. 

Ah ok - wasn’t going to change the hot to 10mm - bit late for that