Manifold + Secondary return

[Rich]

Hi all, over the last few days I have been reading up on the best route to go whilst planning my own plumbing. I was originally set on hot water recirculation due to a mixture of the overall size of our build and not being a fan of waiting for the shower to warm up.

After reading all the relevant threads on here I like the idea of manifold distribution (easy isolation, pressure loss, and less joints). Which has led me to where I am now, considering a mixture of manifolds fed via a secondary return loop to keep the home runs as short as possible. 

 

I have done plenty of plumbing on my rentals however these are obviously far more traditional systems and want something more for our own house. I will be carrying out the work my self so again I like the idea of single lengths of plastic pipe from the manifolds to point of use.

 

I have attached a plan of our build overlaid with manifold, Boiler + UVC positions and would be happy for any thought / critique. My initial first thoughts are to lower the number of manifold from 4 down to 2 (dropping manifolds 3/4), also possibly moving the UVC to the position of manifold 2 which may negate the need for secondary circulation all together? (SWMBO doesn't like the idea of my robbing her cupboard however) ?

 

Has anyone gone down this route? or used an alternative after discounting this route? 

DHW 1.pdf

DHW 2.pdf

[ProDave]

I think the first question is where is the HW cylinder going?

 

I would be putting it in that double door cupboard on the landing. That puts it pretty central to all points of use, so a manifold in the bottom of thet cupboard and direct to each room should be fine.  Far far simpler than multiple distributed manifolds.

 

EDIT just seen the plan for the UVC in the garage. Sory but that is the very last place I would put it, the run to e.g the kitchen would be far too long.

[PeterW]

Manifold one and two are fine - don’t need the rest. M-One could be not recirc as it’s close to the UVC. 

 

Instead of putting a cap in the end of M-Two then just put a 22/15 reducer and run the pump for 2 mins an hour and it will keep the manifold hot. Use 10mm down to the kitchen taps and it will be quick. 

 

UVC in a garage is a bit of a heat loss - can you box it in ..?? 

[Rich]

5 hours ago, ProDave said:

I think the first question is where is the HW cylinder going?

 

I would be putting it in that double door cupboard on the landing. That puts it pretty central to all points of use, so a manifold in the bottom of thet cupboard and direct to each room should be fine.  Far far simpler than multiple distributed manifolds.

 

EDIT just seen the plan for the UVC in the garage. Sory but that is the very last place I would put it, the run to e.g the kitchen would be far too long.

 

The cupboard on the landing was my first choice, in fact it's the reason it was on the plans to begin with ?

However SWMBO has long since dreamt up many uses for the space, if I was in a pinch I could over rule her but life would be far easier if I make the garage placement work. Doing away with the recirc altogether Does sound appealing however. 

 

1 hour ago, PeterW said:

Manifold one and two are fine - don’t need the rest. M-One could be not recirc as it’s close to the UVC. 

 

Instead of putting a cap in the end of M-Two then just put a 22/15 reducer and run the pump for 2 mins an hour and it will keep the manifold hot. Use 10mm down to the kitchen taps and it will be quick. 

 

UVC in a garage is a bit of a heat loss - can you box it in ..?? 

 

Thanks @PeterWI was planning on using pir's to activate the pump but on second thoughts your method would be far more efficient given the way we live. 

 

Would a 22mm feed suffice to manifold 2 given the number of showers etc? I have a 32mm main due to living in Wales and requiring domestic fire sprinklers, so I could support a 28mm feed to the manifold if required. 

 

The garage is insulated to the the same level as the house with the exception of the door being a week point (45mm insulated sectional planned) so I was hoping it would be ok in there. Although what your saying could add more wieght to what  @ProDave has suggested. 

[PeterW]

Unless you’ve got a 500 litre UVC planned..... you’ll need 22mm to the manifold as long as you’re not going stupid with the showers. 

 

Have you considered Sunamps instead as the heat loss will be reduced in a garage.  

[Rich]

37 minutes ago, PeterW said:

Unless you’ve got a 500 litre UVC planned..... you’ll need 22mm to the manifold as long as you’re not going stupid with the showers. 

 

Have you considered Sunamps instead as the heat loss will be reduced in a garage.  

 

300L so I'll stick with 22mm. I considered a sunamp after reading a thread on here regarding them.

However I then read the pricelist, I think it was along the lines of 3-4K for the units our house would require. Assuming not much has changed in the last 6 months. 

[Alexphd1]

If you can't have the UVC in the cupboard upstairs then move the UVC to the back right hand side of garage. Run the jack/Jill on bedroom 2/4 ensuite direct it will only be 2-3m of pipe. Have one manifold in upstairs cupboard running rest of house. The runs from the cupboard are pretty short.

[Nickfromwales]

On 23/12/2018 at 19:35, Rich said:

 

300L so I'll stick with 22mm. I considered a sunamp after reading a thread on here regarding them.

However I then read the pricelist, I think it was along the lines of 3-4K for the units our house would require. Assuming not much has changed in the last 6 months. 

Change of £2.3k for the 12. Change of £2k for the 9, and ~£1000 saved every 10years vs owning ( and having to service / inspect ) an UVC. Couple that with no requirement for pressure reduction / relief controls / valves etc and the benefits soon outweigh the uplift in capital cost. Much simpler ( cheaper ) installation too, just cold in and hot out. 

I have just completed one, and am in the middle of another, spacious 3 bedroom property, ( for plumbing etc ), and both feature a HRC ( hot return circuit ). For the first one there are 10mm pipes to all the basins ( qty 3 ), and they have all been left without HRC, however the HRC has been awarded to the kitchen sink as its at the opposite end of the building to the plant room. The way that one is set up is so that the kitchen sink is the last outlet of the DHW manifold, thus heating the primary DHW 22mm pipework / manifolds etc and killing the dead leg of water off between the water heater and the manifold. As that is all larger bore, it creates a problem without a HRC as it increases the amount of dead ( cold ) water that needs to be drawn off by a sink / basin before getting premium temp DHW out of that particular outlet. As the kitchen sink HRC operates with occupancy, the manifold is always preheated therefore massively reducing the wait for DHW to the basins ( hence now not needing HRC loops to them ). The wait for premium temp water at the kitchen sink is sub 2 seconds, and the wait to any other sink / basin is sub 5 seconds. This house is often unoccupied so works well ( efficiency ) for 'stop / start' living. A side effect of heating the manifold is that all other non HRC outlets benefit from a much improved Dhw 'arrival' time. 

 

On my current project, I have gone a bit more complex as the house will be used almost immediately for a 'retired lifestyle'. First, some basics;

With any HRC arrangement you need to bring all of the HRC return runs back to the point of origin and terminate them in an additional manifold. The reason is, that to be able isolate an individual hot feed to a particular outlet you'll need to do so simultaneously at both the DHW manifold AND also at the HRC 'return' manifold, in order to stop back-flow from the other HRC linked outlets. Because of this, I would recommend a single centralised manifold system and only distributing from there

 

 @Rich, if you do the manifolds as you've suggested you'll acually be worse off not better off as you'll have taken larger bore 22mm pipework all the way through the building and will have increased the amount of dead leg water volume significantly throughout. Running a basin from the upper floor manifold would be painful in terms of wasted water and time lapsed trying to get hot water there to wash your hands after a pee. Don't do the upper manifold. . For you, I'd recommend the single manifold and HRC with the UVC in the garage ( as we both know that's where it's going to end up  ). Losses from an HRC are really pennies in the grand scheme so don't be put off by eco-warriors telling you the running cost will be high, it won't. Simply manage it with a timeclock so it's sleeps whilst you do, and it shuts off when you leave for the day. Insulate the hot and HRC grouped runs accordingly. See my next for a neat solution. 

 

Now, to clarify on HRC awarded outlets, you do not want to include any baths, showers, or other infrequent / high volume drawn outlets. If you run a shower then the longest you'll have to wait for premium temp DHW will be around 10 seconds or less, same or less with a bath. Reason for discounting those is that they're infrequent use / high flow rate outlets, and waiting a short while to get them up to temp is of little or zero consequence given how long you use them and the ratio of dead / lost water compared to the total amount drawn.

 

A HRC is a great thing to have too IMO, when implemented correctly, as not having to wait for hot water eg to wash your hands quickly after using the loo / wanting to quickly swill something in the sink is something you'll soon get fond of. FYI my combi is about 2.5 and 4m away from both my basins ( all ground floor rear ) and less than 2m from my kitchen sink but I still get annoyed waiting for the 4-5 seconds to wash my hands after using the loo. 

 

Ok. On the current one we've gone for a full on, both barrels smoking HRC setup for instant DHW output ( at each HRC awarded outlet ) and I came up with a good idea ( IMO anyway, tin hat at the ready ) for managing the HRC to minimise these 'end of days' losses ?. As most folk will be installing an burglar alarm ( most, so no need to shout at me if you don't have one ? ) I decided to contact the alarm installer and ask for him to supply a couple of relay boards so I could activate the HRC from the alarm panel status;

So :-

 

alarm off = occupied = full HRC operation

alarm full on = unoccupied = HRC off

drumroll please...........

alarm part-armed = no ground floor activity at night = HRC set to part coverage. 

 

In the part-armed state the ground floor HRC circuits ( kitchen sink / utility sink / cloakroom WC basin ) are shut off by some ball valves, and only the 1st floor master and ensuite basins have circulation to them. That's going to be achieved by separating the HRC return manifolds into 2 'groups' so they can be; "all off", "on group 1", or "all on", respective to the state the alarm panel dictates. Couldn't be easier. 

 

This dwelling has a reasonably sized multi directional Pv array with Sunamp ( x3 ) heat battery storage, so in actual fact running the HRC will likely never actually see a running cost. Battery storage ( AC ) is set to feature too, so not even running the HRC pump should have an impact. 

 

Re insulation of the pipes, simply do as I'm currently doing and run both the 10mm HRC and a the 15mm DHW pipe together and insulate them both with one piece of thick walled 22mm insulation. They fit perfectly. Terminate each dual run at the outlet with the 15mm terminating into a 15mm x 10mm 'centre' tee, the 10mm terminating in a street elbow, and the 10mm then fits in to the side ( centre ) of the vertically rising tee and you get the 15mm top of the tee left for the final outlet connection.

 

@Rich, are you having Pv ?

 

Edited December 26, 2018 by Nickfromwales
Bit of extra clarity and sort my chuffing typos.

[Tennentslager]

That last post is a thing of beauty and poetry...didn't understand it all but get the gist.

Arise Sir Nick 

[Rich]

7 hours ago, Nickfromwales said:

Change of £2.3k for the 12. Change of £2k for the 9, and ~£1000 saved every 10years vs owning ( and having to service / inspect ) an UVC. Couple that with no requirement for pressure reduction / relief controls / valves etc and the benefits soon outweigh the uplift in capital cost. Much simpler ( cheaper ) installation too, just cold in and hot out. 

 

I could be convinced at that money, however after a small amount of research around 6 months ago it was looking like I would require 2 units due to the size of house, would this not be the case with the "12"? 

 

7 hours ago, Nickfromwales said:

I have just completed one, and am in the middle of another, spacious 3 bedroom property, ( for plumbing etc ), and both feature a HRC ( hot return circuit ). For one, I have used 10mm pipe to all the basins ( qty 3 ) without HRC to those and have only pit an active HRC run to the kitchen sink as its at the opposite end of the building to the plant room. The way that one is set up is so that the kitchen sink is the last outlet of the DHW manifold, thus heating the primary DHW 22mm pipework / manifolds etc and killing the dead leg of water off between the water heater and the manifold. As that is all larger bore, it creates a problem without a HRC as it increase the amount of dead ( cold ) water that needs to be drawn off by a sink / basin before getting premium temp DHW out of that particular outlet. As the kitchen sink HRC operates with occupancy, the manifold is always preheated therefore massively reducing the wait for DHW to the basins ( hence now not needing HRC loops to them ). The wait for premium temp water at the kitchen sink is sub 2 seconds, and the wait to any other sink / basin is sub 5 seconds. This house is often unoccupied so works well ( efficiency ) for 'stop / start' living. 

 

I think I understand where your going with this, run the last circuit on the mainifold to a point of use and then return from the points use back to the uvc. Therefore the hrc will heat the manifold and manifold feed pipework along with the kitchen circuit? Clever and something I wouldn't of come up with! 

 

7 hours ago, Nickfromwales said:

 

On my current project, I have gone a bit more complex as the house will be used almost immediately for a 'retired lifestyle'. First, some basics;

With any HRC arrangement you need to bring all of the HRC return runs back to the point of origin and terminate them in an additional manifold. The reason is, that to be able isolate an individual hot feed to a particular outlet you'll need to do so simultaneously at both the DHW manifold AND also at the HRC 'return' manifold, in order to stop back-flow from the other HRC linked outlets. Because of this, I would recommend a single centralised manifold system and only distributing from there

 

does anyone make a purpose made manifold for this? or would you just make 2 up from the usual 2/3/4port offerings from jg/hep

 

7 hours ago, Nickfromwales said:

 

 @Rich, if you do the manifolds as you've suggested you'll acually be worse off not better off as you'll have taken larger bore 22mm pipework all the way through the building and will have increased the amount of dead leg water volume significantly throughout. Running a basin from the upper floor manifold would be painful in terms of wasted water and time lapsed trying to get hot water there to wash your hands after a pee. Don't do the upper manifold. . For you, I'd recommend the single manifold and HRC with the UVC in the garage ( as we both know that's where it's going to end up  ). Losses are really pennies in the grand scheme so don't be put off by eco-warriors telling you the running cost will be high, it won't. Simply manage it with a timeclock so it's sleeps whilst you do, and it shuts off when you leave for the day. Insulate the hot and HRC grouped runs accordingly. See my next for a neat solution. 

 

I think from the comments here this seems like the most efficient route, would you also run the shower room above the cylinder back from the manifold for ease of isolation etc?

 

7 hours ago, Nickfromwales said:

 

Now, to clarify on HRC awarded outlets, you do not want to include any baths, showers, or other infrequent / high volume drawn outlets. If you run a shower then the longest you'll have to wait for premium temp DHW will be around 10 seconds or less, same or less with a bath. Reason for discounting those is that they're infrequent use / high flow rate outlets, and waiting a short while to get them up to temp is of little or zero consequence given how long you use them and the ratio of dead / lost water compared to the total amount drawn. A HRC is a great thing to have too, when implemented correctly, as not having to wait for hot water eg to wash your hands quickly after using the loo / wanting to quickly swill something in the sink is something you'll soon get fond of. FYI my combi is about 2.5 and 4m away from both my basins ( all ground floor rear ) and less than 2m from my kitchen sink but I still get annoyed waiting for the 4-5 seconds to wash my hands after using the loo. 

 

Ok, on the current one we've gone for a full on, both barrels smoking HRC setup for instant DHW output ( at each HRC awarded outlet ) and I came up with a good idea ( IMO anyway, tin hat at the ready ) for managing the HRC to minimise these 'end of days' losses ?. As most folk will be installing an burglar alarm ( most, so no need to shout at me if you don't have one ? ) I decided to contact the alarm installer and ask for him to supply a couple of relay boards so I could activate the HRC from the alarm panel status;

So :-

 

alarm off = occupied = full HRC operation

alarm full on = unoccupied = HRC off

drumroll please...........

alarm part-armed = no ground floor activity at night = HRC set to part coverage. 

 

In the part-armed state the ground floor HRC circuits ( kitchen sink / utility sink / cloakroom WC basin ) are shut off by some ball valves, and only the master and ensuite basins have circulation to them. That's going to be achieved by separating the HRC return manifolds into 2 'groups' so they can be; all off, on group 1 or all on respective to the state the alarm panel dictates. Couldn't be easier. 

 

This is dwelling has a a reasonably sized multi directional Pv array with Sunamp ( x3 ) heat battery storage, so in actual fact running the HRC will likely never actually see a running costs. Battery storage ( AC ) is set to feature too, so not even running the HRC pump should have an impact. Do as I'm currently doing, and run both a 10mm HRC and a 15mm DHW together, insulated by one piece of thick walled 22mm insulation. They fit perfectly. Terminate each dual run at the outlet with the 15mm terminating into a 15mm x 10mm 'centre' tee, the 10mm terminating in a street elbow, and the 10mm then fits in to the side ( centre ) of the vertically rising tee and you get the 15mm top of the tee left for the final outlet connection.

 

A very neat solution! It's something I could add a version of as I'm putting loxone automation in (another learning curve for me). This could be used for a similar level of control. 

 

7 hours ago, Nickfromwales said:

@Rich, are you having Pv ?

 

 

Sadly not, I did have a quote I was happy with (circa 4.5k for 4kw in roof) however I had a little last minute doubt in the "investment"due to not having a Epc lowering the kickbacks.

 kicking myself a little now as the roofs on so too late and it would have only cost 3.6k once I had them take the vat off! So would have been a fairly fast payback! ?

 

I think I managed to digest most of what you wrote ? Thanks for the help. 

 

[Nickfromwales]

2 hours ago, Rich said:

I could be convinced at that money, however after a small amount of research around 6 months ago it was looking like I would require 2 units due to the size of house, would this not be the case with the "12"? 

Not all about the size of the house chief, it's about how much water you're going to use . Remind me of how you intend to heat the water please? 

 

2 hours ago, Rich said:

Clever and something I wouldn't of come up with! 

I'm a veritable feast of random crap like that ?

 

2 hours ago, Rich said:

does anyone make a purpose made manifold for this? or would you just make 2 up from the usual 2/3/4port offerings from jg/hep

Just make them up as required. Simples. 

 

2 hours ago, Rich said:

would you also run the shower room above the cylinder back from the manifold for ease of isolation etc?

Run that by me again ? Turkey-induced coma at the mo. When you say room, do you mean to all the outlets in the one room?

 

2 hours ago, Rich said:

This could be used for a similar level of control. 

Yup. I believe my next couple of victims are going down the same route. 

 

2 hours ago, Rich said:

kicking myself a little now as the roofs on so too late and it would have only cost 3.6k once I had them take the vat off!

Please don't kick yourself over this........allow me, as the wife says I need to start exercising more.  Win, win.  

[Rich]

16 minutes ago, Nickfromwales said:

Not all about the size of the house chief, it's about how much water you're going to use . Remind me of how you intend to heat the water please? 

 

will be a gas boiler, size/brand I'm open to suggestions, however most of the gas safe fitters around here have their fave to fit for what ever reasons. 

There's only 3 of us so no real heavy use but thus may not always be the case. 

 

Quote

Run that by me again ? Turkey-induced coma at the mo. When you say room, do you mean to all the outlets in the one room?

 

what I mean is since it's directly above the garage it would seem a little daft to run this from the single proposed manifold in the upstairs cupboard? 

Would this just be run from the cylinder/sunamp position straight up?

Quote

 

Yup. I believe my next couple of victims are going down the same route. 

 

Please don't kick yourself over this........allow me, as the wife says I need to start exercising more.  Win, win.  

 

? I'm trying not to dwell on it to much, however I'm fairly sure its going to end up as the biggest mistake of the build! 

Oh well at least I won't have to wait for hot water to wash my hands after a jimmy riddle ?

 

[Nickfromwales]

If it's a gas boiler then you could manage with a single ( Sunamp ) 12 with ease. I'd say a 9 would probably cut it, but that would be borderline for your house at 212L uvc equivalent capacity. A 12 will walk it, as long as the gas boiler isn't allowed to service DHW according to demand. 

How about putting the manifold(s) in the airing cupboard and just having the SA in the garage? Less pipe work, less losses and any waste heat off the manifold / connective pipework will keep your trollies warm. 

Typically you'd only go for a manifold arrangement throughout, and not leave a room out. The idea is not to have any series plumbed outlets thus negating starting off with big dead legs. A HRC with a series plumbed house is quite indiscriminate so you won't be able to discount any outlets like you can with radial + manifold. 

Get back to the drawing board and see which setup will have the biggest benefit me thinks   

[Rich]

On ‎27‎/‎12‎/‎2018 at 01:10, Nickfromwales said:

If it's a gas boiler then you could manage with a single ( Sunamp ) 12 with ease. I'd say a 9 would probably cut it, but that would be borderline for your house at 212L uvc equivalent capacity. A 12 will walk it, as long as the gas boiler isn't allowed to service DHW according to demand. 

How about putting the manifold(s) in the airing cupboard and just having the SA in the garage? Less pipe work, less losses and any waste heat off the manifold / connective pipework will keep your trollies warm. 

Typically you'd only go for a manifold arrangement throughout, and not leave a room out. The idea is not to have any series plumbed outlets thus negating starting off with big dead legs. A HRC with a series plumbed house is quite indiscriminate so you won't be able to discount any outlets like you can with radial + manifold. 

Get back to the drawing board and see which setup will have the biggest benefit me thinks   

 

 

I've been back over the plan and have come up with the manifold plan as attached (1 single manifold in the cupboard as @Nickfromwales suggested), the UVC/Sunamp will stay in the garage and the decision on which of the 2 can be made later as first fix pipework in the house is the priority at the moment.

I've planned the basins sinks and showers as return circuits for comfort (although part of me thinks the showers being return circuits maybe a little overboard they cost so little to add?)

as @PeterWthe manifold and 22mm feed leg should be kept warm by activating the HRC for a couple of mins a hour  for any outlets omitted from the return circuits (bath + shower 1)

 

in the same cupboard will be a manifold to feed 1st floor and attic radiators (currently trying to find a pushfit 10mm manifold) they all seem to be 15mm, this should allow me to control actuators via loxone to zone the heating. 10mm feed and return from rads?

 

Then the ground floor ufh manifold in the garage (insulated enclosure).

 

anything obvious missing from the above plan? anything any of you would do differently? am I still going way over the top? (so easy to do when its your own build ?)

 

Thanks in advance.

drg 1.pdf

drg 2.pdf

Edited December 28, 2018 by Rich

[PeterW]

4 minutes ago, Rich said:

anything obvious missing from the above plan? 

 

The plan itself ......?? ?

[Rich]

5 minutes ago, PeterW said:

 

The plan itself ......?? ?

 

? done.

[PeterW]

6 minutes ago, Rich said:

the same cupboard will be a manifold to feed 1st floor and attic radiators (currently trying to find a pushfit 10mm manifold) they all seem to be 15mm, this should allow me to control actuators via loxone to zone the heating.

 

Don’t bother trying to find a 10mm pushfit manifold - just use a standard UFH one and a short leg of 16mm UFH pipe and then use a reducer or see if you can get a manifold with 15mm eurocones on it and 15/10 is an easy size to find in pushfit.