oranjeboom

Plumbing questions (15mm all in? Pipe runs....)

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Somehow I have told the boss we'll be in for Christmas....😱 Most likely 2019 though, but I did not mention that....   But ideally would like to have the downstairs livable with at least 1 bathroom, kitchen and UFH in operation, which means I need to get my skates on.
 
For my retro-extension I will have 2 bathrooms (1 upstairs, above bedroom 3), utility with WC and Kitchen. I have 2x 12kw Sunamp units that will provide DHW and also my UFH (real life testing will prove whether I need to go for an ASHP/off-grid PV panels next year, but that will be another topic...).
 
Looking to getting my plumbing sorted and have decided to go for plastic over copper using a manifold setup for most rooms.
 
  • Pipe runs are fairly short, with the longest being to the kitchen (18m) - can't avoid that.
  • Water flow (42L/minute) and pressure (6bar iirc) are all good. 
  • Sunamp units will be located in the cloakroom ("CLKS") so a short distance to the manifolds next door (1.5m ish) in the utility room
  • UFH manifold is located next to Sunamp units
  • The upstairs bathroom will be located above bedroom 3 with a piperun of approx 10m max to the furthest outlet
 
My plan was to use:
 
  • 15mm pipe for all runs/ to all outlets. I believe CJARD on ebuild had that approach as did @JSHarris so I can't be too far off.
  • Instant hot water tap in kitchen so hot water pipe would be pretty much redundant (unless i use it for mega washing up session) so I don't think there is a need for HRC. Only potential 'hot water wait' outlet will be upstairs for shower/bath but that will only be 9m run.
 
 
I was going to use 10mm for some outlets such as toilets and basins ("to reduce water velocity and stop the WC from over monopolising water pressure" as per @Nickfromwales) but will obviously need reducers which brings extra cost and another potential leaky join - though hep20 is pretty fool proof I read!), so if I can stick to 15mm all round, then I can just get two rolls of 100m. So hopefully can do without 10mm?plumbing plan.pdf
 
Any flaws in my thinking?
 
I'll have more questions with the finer details no doubt (PRVs, NRVs etc) later on!
 
Attached is a rough plan. Pipe runs are indicative only at this stage but show their relative locations. NB: Kitchen run has to go the route as indicated due to cathedral ceilings. Cold water pipe runs not shown but will be roughly in same routes as hot. Upstairs not shown seperately but located above bedroom 3.
 
Edited by oranjeboom
forgot the bloomin' pdf!

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With 2x12kW PCM58's you'll have about 27kWh of heat capacity and 6kW of electrical input so as long as your peak space heating demand doesn't exceed the 6kW then you'll be fine. DHW will come from the redundant capacity that will reside in the units, when they're fully charged. I imagine they're both 'eDual' units, so basically both units can lend either space heating or DHW to each other for maximum ( combined ) effect. I doubt you'll go wrong with that setup unless your in a draughty 1980's build with single glazing. ;)

 

For the kitchen run, can you not chase a pipe into the floor and insulate it? Then your as the crow flies and will reduce that run significantly. With that kind of flow rate and pressure you could easily run the kitchen hot feed in 10mm for even more reduction in 'delay to tap', plus its a no brainer to dos the same with all the other hot feeds to basins / sinks. Get over the extra 1 fitting each end of the run, but TBH if you shop clever you can even reduce that. 10mm x 1/2" male straight to the Flexi :). "Just do it man !"

 

All other cold feeds to be 15mm

All other hot feeds to be 15mm

On that basis, the plan seems a good one to me. 

 

The reason for a HRC pump on even that small a setup is because the manifold introduces a primary pipework arrangement which needs to be all 22mm, eg from the SA units to the manifolds, then the manifolds themselves are 3/4", and then the small bore 'distribution' pipework starts from there. You otherwise must factor in having to discharge all of that 'dead leg' of DHW prior to it getting out of the desired outlet so think twice about a HRC as it does make a big difference.

Eg to run the upstairs basin and get hot water the water must travel out of the secondary SA unit ( the heat exchanger will be hot already as the SA's are instant water heaters ) and go through the interconnecting 22mm pipework prior to the manifold, and then through the manifold, before the reduction in the distribution pipework has a chance to carry out its intended function ( to reduce the volume of water two discharge before getting premium temperature water from the chosen outlet ). At the least, and as a start point, I'd fit a Grundfos Comfort HRC pump to simply circulate between the SA's and the manifold, so the primary arrangement was always 'at temp' and ready to deliver.

 

Remember that having great pressure and flow will be of little consequence at the basins as you wont be able to run them very fast without getting splashing water everywhere ( if that was assumed in an attempt to discharge the dead leg ). Basins exaggerate the problem because typically they are outlets which are used 'little and often' and therefore anything even slightly excessive lengths in the preceding pipe run can see you washing your hands before hot water has arrived.

 

The Grundfos Comfort is a very energy efficient pump so is not quite the 'extravagance' that some may see it as. Compare a house that has it to one that doesn't and you'll soon warm to it.  

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@Nickfromwales - Thanks for the info Nick! I have some comments below and some qs also!

 

23 hours ago, Nickfromwales said:

I imagine they're both 'eDual' units, so basically both units can lend either space heating or DHW to each other for maximum ( combined ) effect. I doubt you'll go wrong with that setup unless your in a draughty 1980's build with single glazing. ;)

 

 

 

Yes 2x eDual units. Floors fully insulated, will have EWI and plenty of loft roll/PIR in every crevice I can force it. 3G windows. Hopefully better than a tent (at least the weight of the Sunamps will stop the tent from flying away!)

 

23 hours ago, Nickfromwales said:

For the kitchen run, can you not chase a pipe into the floor and insulate it? Then your as the crow flies and will reduce that run significantly.

 

Don't go down that path!!   

Concrete floor is all UFH and I don't want to be digging any of that out again!  So my only choice is that long run. But I will be having that  Quooker type tap in the kitchen so the hot tap will barely see use. But I'll go for the 10mm runs for hot and cold then for the kitchen then and all other sinks/basins - also for toilets I guess?

 

With regards to the HRC - is that really needed between the sunamps and the manifolds? The distance would only be around 3m, but I guess if that is to be 22mm, then there is extra volume involved.

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Best to warm the manifold with a blended HRC circuit imo, and remember it can be timed so not running 24/7.

For one client I have designed the HRC to switch on and off in line with the burglar alarm so when armed ( out or sleeping ) the HRC shuts off. 

Make sure the cold feeds to the kitchen / utility / baths / showers are done in 15mm NOT 10mm. They’ll struggle in 10mm. You only want 10mm to ( optional ) the WCs and the hot taps on basins / sinks. 

 

2 hours ago, oranjeboom said:

Don't go down that path!!

Oops lol. 😣

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Thanks @Nickfromwales. Yes, I was thinking of having a timer of some description for the HRC to the hot manifold.

 

I've added pipe sizing to each outlet now on my crappy sketch below (Visio pi55ing me off!)  and think that tallies up with what you recommended. Ignore the pipework between the UFH manifold and the Sunamps - I haven't looked at the SA instructions yet and will most likely get a plumber to assist me with that side of things.

 

I have added a water softener as it's all 'well 'ard' down this way, innit. Not sure what system to go for, but I have seen a thread about that elsewhere on BH to read up on.

 

1) I also have a feeling that I need a non-return valve somewhere - between the stopcock and PRV?

 

2) As for the actual pipe, as I'm not using this for heating, I presume I may as well just go for the standard Hep20 rather than the barrier type pipe? Any good online merchants for Hep2o? Wickes appear competitive at £40 for 15mm 25m barrier pipe using the 10% discount offer. Looks like their are better prices on barrier than std.

 

IMG_1052.JPG

IMG_1053.JPG

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If you haven’t got an accumulator then don’t worry about doubling back from the ends of the manifolds to feed both ends, that was only for Uber high flow rates ;)  

Instead, just put the higher flow items nearer the input side eg bath - shower 1 - shower 2 - kitchen sink - basin 1 - basin 2 and so on. 👍

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1 hour ago, Nickfromwales said:

If you haven’t got an accumulator then don’t worry about doubling back from the ends of the manifolds to feed both ends, that was only for Uber high flow rates ;)  

Instead, just put the higher flow items nearer the input side eg bath - shower 1 - shower 2 - kitchen sink - basin 1 - basin 2 and so on. 👍

Oh, okay. That makes it simples then. I like simples. Just retain the hot return from the hot, manifold, correct?

 

1 hour ago, Nickfromwales said:

Oh, and why the PRedV ?

 

Cos I got over 6bar innit. I have a private water setup from the neighbouring landowner and there could be a potential for the pressure to increase when they aren't using water, so I thought it be best to have a pressure reducer/limiter. Not read the sunamp material yet, but I guess that may need protection. Also, water softener may need pressure limited too? The PredV is fitted already.

 

Oh yes, do I need a non-return valve anywhere?

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Order of events;

1) incoming cold main

2) stopcock immediately as it rises 

3) double check NRV

4) drain off cock ( DOC )

5) outside tap

6) PRedV

7) wadevayalikefromthere

 

FYI SA is good for 10 bar but recommendation is a PRedV set at 5-6bar, but most softeners need 4-5bar restriction anyway. 

Read the MIs of the chosen softener for the correct rating ;)  

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@Nickfromwales Thanks again!

 

wadevayalikefromthere - does that come in 22mm? Will ask in Toolstation tomorrow.

 

5 hours ago, oranjeboom said:
6 hours ago, Nickfromwales said:

If you haven’t got an accumulator then don’t worry about doubling back from the ends of the manifolds to feed both ends, that was only for Uber high flow rates ;)  

Instead, just put the higher flow items nearer the input side eg bath - shower 1 - shower 2 - kitchen sink - basin 1 - basin 2 and so on. 👍

Oh, okay. That makes it simples then. I like simples. Just retain the hot return from the hot, manifold, correct?

 

Just retain the hot return from the hot manifold, correct?

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1 hour ago, oranjeboom said:

@Nickfromwales Thanks again!

 

wadevayalikefromthere - does that come in 22mm? Will ask in Toolstation tomorrow.

 

Just retain the hot return from the hot manifold, correct?

Yup. It won’t use much energy but will make the system far more user friendly. I wouldn’t like to spend on a new system but then have to wait for the hot water to come out of the taps. 

Youll thank me later ( or send me the bill for the pump lol ). 

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@Nickfromwales - I will thank you NOW Nick - your input is always appreciated.

 

Have any forumites bought any Hep2o recently? As I'm not using this for heating, I presume I may as well just go for the standard Hep20 rather than the barrier type pipe? Any good online merchants for Hep2o? Wickes appear competitive at £40 for 15mm 25m barrier pipe using the 10% discount offer. Looks like their are better prices on barrier than std.

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JTM are £36 inc VAT for 25m

 

About the cheapest I’ve found it

 

 

 

  • Thanks 1

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2 hours ago, PeterW said:

JTM are £36 inc VAT for 25m

About the cheapest I’ve found it

Cheers. Going to need a couple of hundred metres of it soon. 

 

Anyone got a heads up on ready ( pre ) insulated 15mm & 10mm ? Found a supplier and asked for a price on 250 / 500m breaks but I think I’m too little a fish to catch their interest. :/ 

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Son of a......

The dual system is what I’ve been looking for, for hot + hot return ( 22mm+15mm or 15mm + 10mm etc ) in the same insulated runs. 

Even if it’s expensive it’ll make a cheap alternative to lagging 250m of 15mm by hand ;)  You can get a lot done in a day with that stuff. 👌

Cheers.  

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You know where to send the cheque... 

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5 minutes ago, PeterW said:

You know where to send the cheque... 

 

I think that's a pipe dream... :ph34r:

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8 minutes ago, Onoff said:

 

I think that's a pipe dream... :ph34r:

 

That's terrible! Really don't see why you had to pipe up this time of night.

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13 minutes ago, oranjeboom said:

 

That's terrible! Really don't see why you had to pipe up this time of night.

 

You're lagging mate, already used the phrase "pipe"! 

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Let's not sink to these new low-levels of humour shall we??

 

So now I see that there's not a 4 port 15mm manifold - great. The setup was to be in a fairly confined space as it is and having 2x 2ports in place of a 4 port manifold is going to take up space with additional connectors. I could get use the brass manifold type instead, but the prices put me off (£43!!!), but the advantage they have is that they look better (although no one's going to see it!) and they have the inbuilt valves which I would also have to add to a full plastic setup. Are there any other advantages going for a brass manifold setup???

 

Any cheaper sources for the brass buggers? https://www.jtmplumbing.co.uk/pipe-fittings-c433/hep-o-brass-manifold-and-fittings-c661/hep2o-four-port-valved-manifold-15-tm-tf-fp-p21691

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