Final Qs about pipe diameters

[Nickfromwales]

7 hours ago, Adsibob said:

I'm sure there are other benefits that I'm missing, but glad I went with secondary loop over a manifold. Not sure what @Dan F thinks is their benefit in this situation?

There are many benefits, and I never carry out an M&E project without manifolds for hot, cold, AND hot return. Sometimes the client only needs 2 outlets with HRC, but they still go on a dedicated HRC manifold regardless. Reason being is that the hot supply and the HRC both terminate immediately before the outlet, so to kill the individual hot to a particular ( HRC serviced ) outlet you need to be able to isolate both the hot feed, and the HRC loop to 100% shut off supply. 

As above, you can design out the need for an HRC, but those instances are usually based on an ideal layout / positioning of hot water device vs hot outlets, or with a caveat that a little delay to a couple of the furthest outlets is tolerated. Mitigated by correct pipe-sizing mostly, but still suffers if there is larger bore pipework before the distribution manifold, as there can be a much bigger dead leg there vs any of the terminal pipe runs. 

I often set up the hot manifold to have the HRC serviced outlets come from the far end of the hot manifold, eg opposite end to the hot water supply, so as to pre-heat the rest of the manifold and maximise the benefits created with shortened / correctly sized pipe runs. Current project will also feature occupancy switches ( PIR detectors ) to run the HRC only when a room is occupied, and only for a set 'on time'.

@Adsibob I think with your hot return loop done with series plumbing, there are a good few disadvantages, and even without a manifold aka radial arrangement you should have had a better tactic for HRC deployment, particularly if you already knew the water would need to be recirculating for extended periods whilst you relaxed in the bath.

Are all your hot runs very well insulated? I typically run the 15mm radial hot feed and its partnered 10mm HRC together, in a single wrap of 22mm dia x 25mm wall Climaflex pipe insulation, to massively reduce heat losses from that often lengthy pipe run. This  also preserves the residual heat in the pipe(s) after the HRC pump has cycled and shut off, which reduces the amount of cold dead leg shunted back to the hot water device at each 'pump on' event.

7 hours ago, Adsibob said:

But we are plumbing everything from new, I'm hoping it's done properly so that that won't be necessary.

It would be minimum industry standard practice to install a suitable ballofix / other isolation valve immediately where the pipe run terminates at each outlet, so you do not have to shut down the entire wet system in the event of a single device failing / needing service. If you do not have these then it's a poor installation IMO. The manifold provides means of remotely and centrally mounting these isolation valves, so for eg shower mixers and bath fillers, often with nowhere to practically access such local isolation valves, can benefit from this also.

On 20/11/2021 at 20:34, Adsibob said:

2. what happens to an outlet further down the secondary loop when one opens the bath filler (which is rated at 33L/min) that is served by the 22mm secondary loop? Would the majority of the water in the secondary loop go to the bath meaning another outlet further along the secondary loop (i.e. further away from the UVC) that is trying to compete with the bath filler would really struggle, or would a fairly decent flow rate of say 25L/per minute, together with the 3 bar pressure from the UVC ensure that dynamic pressure is sufficient that the other outlet is still usable.

This is the Achilles heel of series plumbing. Outlets have to share the flow dynamics of the pie run that feeds them all. That's usually mitigated with a very big pipe run at the hot water device, 22mm or even 28mm, then diminishing as it gets further away, usually down to no smaller than 15mm. If your hot supply is also the HRC loop then that can be more problematic, as it should arrive back at source via a non-return valve, so the return pipe side cannot 'back-feed' the outlet, ergo the furthest hot outlet will always be the worst performing / most affected outlet eg where other outlets are opened upstream whilst it is being used. A real PITA if that happens to be a shower.

I converted to radial + manifold over 9 years ago and will never go back to series, unless its a flat with one bathroom / kitchen and they're all next to each other etc where it's then just not justifiable.

[TonyT]

9 hours ago, TonyT said:

Will post a link tomorrow when I get the info from work as I can’t remember the name.

 

my mates the m&e clerical works manager at the local council,  and a few of the local universities have done trials/case studies..

 

 

 

https://www.endotherm.co.uk

 

[Nickfromwales]

5 hours ago, TonyT said:

https://www.endotherm.co.uk

 

I read all that but it doesn’t say anywhere about making the “water wetter” 

 

 

?. 
Kind of thing I’d write tbh, but made me chuckle lol. ?

[Adsibob]

8 hours ago, Nickfromwales said:

There are many benefits, and I never carry out an M&E project without manifolds for hot, cold, AND hot return. Sometimes the client only needs 2 outlets with HRC, but they still go on a dedicated HRC manifold regardless. Reason being is that the hot supply and the HRC both terminate immediately before the outlet, so to kill the individual hot to a particular ( HRC serviced ) outlet you need to be able to isolate both the hot feed, and the HRC loop to 100% shut off supply. 

As above, you can design out the need for an HRC, but those instances are usually based on an ideal layout / positioning of hot water device vs hot outlets, or with a caveat that a little delay to a couple of the furthest outlets is tolerated. Mitigated by correct pipe-sizing mostly, but still suffers if there is larger bore pipework before the distribution manifold, as there can be a much bigger dead leg there vs any of the terminal pipe runs. 

I often set up the hot manifold to have the HRC serviced outlets come from the far end of the hot manifold, eg opposite end to the hot water supply, so as to pre-heat the rest of the manifold and maximise the benefits created with shortened / correctly sized pipe runs. Current project will also feature occupancy switches ( PIR detectors ) to run the HRC only when a room is occupied, and only for a set 'on time'.

@Adsibob I think with your hot return loop done with series plumbing, there are a good few disadvantages, and even without a manifold aka radial arrangement you should have had a better tactic for HRC deployment, particularly if you already knew the water would need to be recirculating for extended periods whilst you relaxed in the bath.

Are all your hot runs very well insulated? I typically run the 15mm radial hot feed and its partnered 10mm HRC together, in a single wrap of 22mm dia x 25mm wall Climaflex pipe insulation, to massively reduce heat losses from that often lengthy pipe run. This  also preserves the residual heat in the pipe(s) after the HRC pump has cycled and shut off, which reduces the amount of cold dead leg shunted back to the hot water device at each 'pump on' event.

It would be minimum industry standard practice to install a suitable ballofix / other isolation valve immediately where the pipe run terminates at each outlet, so you do not have to shut down the entire wet system in the event of a single device failing / needing service. If you do not have these then it's a poor installation IMO. The manifold provides means of remotely and centrally mounting these isolation valves, so for eg shower mixers and bath fillers, often with nowhere to practically access such local isolation valves, can benefit from this also.

This is the Achilles heel of series plumbing. Outlets have to share the flow dynamics of the pie run that feeds them all. That's usually mitigated with a very big pipe run at the hot water device, 22mm or even 28mm, then diminishing as it gets further away, usually down to no smaller than 15mm. If your hot supply is also the HRC loop then that can be more problematic, as it should arrive back at source via a non-return valve, so the return pipe side cannot 'back-feed' the outlet, ergo the furthest hot outlet will always be the worst performing / most affected outlet eg where other outlets are opened upstream whilst it is being used. A real PITA if that happens to be a shower.

I converted to radial + manifold over 9 years ago and will never go back to series, unless its a flat with one bathroom / kitchen and they're all next to each other etc where it's then just not justifiable.

I have no doubt that you are right about this @Nickfromwales, but unfortunately I don't understand it anywhere near enough to supervise my plumber and check he is doing things properly. In particular, I'm not sure I understand how a radial + manifold system would work together with a secondary loop. Or are you saying that these are mutually exclusive options?

Ultimately, All the hot water outlets are in very close proximity to the UVC in that one shower and basin is literally within 1m from it, the master ensuite where the large bath is, is almost directly under the UVC, the family bathroom where a medium bath, shower and basin are are next to that master ensuite. The only outlets that are slightly further away are the guest WC basin on the ground floor and the kitchen tap.

For this kind of layout (and it's a tall house(Ground, first and second), rather than a wide one):

1. how many manifolds would there be?
2. where would the manifolds be?
3. would there also be a secondary loop and if so which outlets would it serve?

Thanks so much

 

 

 

[Dan F]

1 hour ago, Adsibob said:

I'm not sure I understand how a radial + manifold system would work together with a secondary loop. Or are you saying that these are mutually exclusive options?

The approach uses a 10mm hot return for each outlet that needs it (and only the outlets that need it) rather than a common loop i.e. the return is also radial.

 

1 hour ago, Adsibob said:

All the hot water outlets are in very close proximity to the UVC in that one shower and basin is literally within 1m from it, the master ensuite where the large bath is, is almost directly under the UVC, the family bathroom where a medium bath, shower and basin are are next to that master ensuite

So you could plumb all these outlets directly to a manifold next to the UVC.  You may find these don't need a return, depends on exact distance, flow rate and if how many seconds wait is acceptable.

 

1 hour ago, Adsibob said:

The only outlets that are slightly further away are the guest WC basin on the ground floor and the kitchen tap.

These you would you take off of the same manifold and then bring a return a 10mm return from each of them.  If you put these these on the furtherst end of the manifold (as @Nickfromwales suggests) then the recirculation to kitchen and WC, will also heep manifold and pipes to manifold warm, helping with wait time for water to the bathroom basins.

 

[TonyT]

4 hours ago, Nickfromwales said:

I read all that but it doesn’t say anywhere about making the “water wetter” 

 

 

?. 
Kind of thing I’d write tbh, but made me chuckle lol. ?

Changing the surface tension of heating system fluid essentially makes it “wetter”. EndoTherm breaks down the Hydrogen bonds within the fluid resulting in a 60% “wetter” fluid when compared with standard water. A wetter fluid can access and improve contact with the micro-cracks and unavoidable imperfections within a radiator, boiler tube or heat exchanger. Increased thermal contact improves the efficiency of heat transfer into a building.

[Adsibob]

20 hours ago, Dan F said:

 

 Also I think it probably also means less impact on one hot outlet when another outlet is used.

 

 

Just trying to understand this. Why is that the case?

[Dan F]

29 minutes ago, Adsibob said:

Just trying to understand this. Why is that the case?

 

 

It doesn't have to be the case, if things are sized corectly, but it can be otherwise.  I'm pretty sure others have mentioned this as issue in past..so maybe others can comment.

[Nickfromwales]

@Adsibob

If the runs are from hot and cold manifolds, then with the locations / distances as you describe there would be no need for an HRC to any of the outlets other than the guest basin and kitchen sink, IMO.

The bath is so close that your infinite bath top-ups would only have to expel around a half pint of "cold" water before you got premium temp hot water out of the bath tap. That feed would be a 15mm from manifold, with the manifold fed by 22mm from the HRC. ( If your UVC has a 28mm outlet I'd be surprised? )

The manifold + HRC setup is dead simple;

• 22mm hot feed to hot manifold via 22mm TMV ( to maintain the B.Reg for 46oC ( max ) at the bath tap ).
• 22mm cold feed to cold manifold fed from the balanced cold output from the UVC 'control group' ( supplied with the UVC ).
• 22mm connection, from the UVC dedicated HRC tapping, to the HRC manifold ( HRC pump and NRV inline between those two items as required )
• job done.
• 15mm radial runs to all cold outlets for simplicity
• 15mm radial runs to baths / showers
• 10mm hot feeds to everything else
• 10mm HRC returns to the point the HRC serviced hot feeds terminate immediately at the outlet. I use a Hep2O 15x15x10mm "centre" tee and a 10mm spigot elbow to perform these junctions.

Easier than when Christ fell off his bike.

Edited November 23, 2021 by Nickfromwales