TerryE

Another DHW / DCW / UFH design

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I tend to bulk buy fittings anyway - I'm swapping over from Speedfit to Hep2O at the moment so any jobs I do for anyone else get the spare Speedfit ones out of my box ... :ph34r:

 

I've started to use Toolstation more as there is one next to our office - electrical stuff is BG and CEF mainly plus a few others, and plumbing is either Speedfit or an own brand which is a little odd. Pipe prices aren't too bad either. 

 

With JTM and BES I tend to over order anyway and end up with spares but they get used - at 40-60% cheaper than Screwfix I tend not to worry and the likes of B&Q become a last resort..!

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2 hours ago, PeterW said:

Or get them from JTM at £1.48 + VAT....

JTM Brass fittings

 

One issue with JTM is that they only sell standard parts like 22 x 22 x 22 in bulk :(, and I don't think I'll ever use 50× those, but I an always get them at Screwfix.

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End feed (don't use PF copper), but I was being a dozo.  I missed the 1 off items hidden in the bulk buy lists :)

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82p plus vat... 

 

Spend £75 and it will be with you Tuesday too ...

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15 hours ago, PeterW said:

With JTM and BES I tend to over order anyway and end up with spares but they get used - at 40-60% cheaper than Screwfix I tend not to worry and the likes of B&Q become a last resort..!

 

Peter, the JTM site seems a great find.  Much appreciated.  The stuff was ordered last night, and has already been despatched.

 

One other observation re the pressure testing.  One issue with using an air based meter behind a  double check valve is that you can't really use this to check for slow leaks, so I've splashed another £8 for a wet gauge and connector, so that I can crank the test run to 6 bar, say, and isolate it.  If the pressure drops on the wet side, then I've got a leak somewhere :(.  We hummed and harred about even bothering to check all runs before we put the appliances on, but as I said to Jan: it's going to be months before we do some of the wetrooms, so it's better to know now that we haven't got any pipe breaches during boarding out before we start decorating.

 

PS. This thread is a somewhat dynamic and evolving story.  I wonder if it will ever compete with @Onoff's Bath Surround / Boxing In, and concealed pipework?  I will have to roll up a summary for normal mortals when we're done in a blog post :)

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8 hours ago, TerryE said:

PS. This thread is a somewhat dynamic and evolving story.  I wonder if it will ever compete with @Onoff's Bath Surround / Boxing In, and concealed pipework?  I will have to roll up a summary for normal mortals when we're done in a blog post :)

 

:/

3 pages vs 19 @TerryE ?

You've some way to go mate :D

 

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47 minutes ago, Nickfromwales said:

 

:/

3 pages vs 19 @TerryE ?

You've some way to go mate :D

 

 

Cheek! I started it on eBuild in March 2015!

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41 minutes ago, Onoff said:

 

Cheek! I started it on eBuild in March 2015!

I'd keep that quiet if I were you :D

March 2018 deadline then ? May as well set the bar ;)

 

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A quick update.  I've added a wet 0-6 bar gauge to my home-brew pressure test setup and connected up my DCW manifold and cranked it up to 7 bar.

  DCW-manifold-Ttest.thumb.jpg.0382280b28ab8048a3d5c8176b8b06f8.jpg

 

One advantage of breaking your system down into separate subsystems if that you can assemble each on the bench and test properly before installing in place.  To be honest I had a 28mm dry joint so its lucky that we did this.  The problem was that the end of the 28 pipe had a shallow ding in it that I hadn't noticed -- goodness knows why -- but the result was that the end feed solder had a dry bridge, and this caused a joint failure that I needed to redo before the 7 bar test worked.  The main fill will be where the 28mm endstop is to the left and the 15mm below will ultimately have a draincock on it, but  it is currently a pressure test point.

 

And this is the manifold in position.  Not quite as neat as Nick, but it will do :) Compare this to the photos on the original post. 

DCW-manifold-inplace.thumb.jpg.376b414f3e306a7b780afb90ae1721b7.jpg

 

I blame Jan for it being slightly crooked.

 

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Well, I'm happy to say, you've got the job :) You can start Monday. 

Looks neat and tidy to me, and the manifolds are a great solution for negating end-of-line isolation ( and access to more so ). 

Soldering 28mm is almost a skill in itself. The heat at the front of the fitting doesn't always get all the way around the pipe, so most get a dry patch at the rear of the joint, unless the heat has been applied evenly around the whole fitting. Having a dented pipe is a bitch, so you can't lose brownie points ( remember those :D ) for the duff joint B|.

9.5 out of 10. I can't give you 10 sorry, as that may steal my thunder. :ph34r:

 

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When I cranked the system up to 7 bar for the pressure test, I bent the lever on the 4 bar pressure gauge so it now reads ½bar at zero -- oops!!  But to the next sup-topic:

 

Accumulators -- do we need one and how big?

 

It's pretty flat where we live, so our mains is pump-assisted off a small staging reservoir in the forest about 1½km away.  It comes into the house at 3-bar static pressure.  There's an iron water main in the road fitted with a 28mm MDPE spur to our the stopcock/meter on the pavement (I watched the guys do it), and then a ~10m leg of 25mm MDPE across our front garden into the house and our mains stopcock.  From there it will be 28 / 22mm piping to the manifolds.  I've just done a quick 6 sec flow-rate test and the flow-rate through my home-brew pressure test kit is fearsome -- over 35 ltr / min.  OK, the PRV will knock off maybe 0.2 bar, but this flow rate is more than enough to supply two showers in parallel.  

 

So now I am asking myself do I really need an accumulator and if so how big?  I really can't see the point in having a large one.  Thoughts and advice please experts?  

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I'd say not.  Accumulators take up a fair bit of space if they are to hold a decent volume (they only hold less than half their rated volume as pressurised water), the membranes have a finite life (typically around 10 years or so) and they do need to be emptied and have the pre-charge air pressure checked at least once a year.  If you can manage without them then that's what I'd do (and we have two 300 litre ones plus a 100 litre one!).

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I'd only recommend one to offset the effect of a loo flushing or white goods filling. With your pressure and flow rates I'd leave space for one, and pipework provisioned accordingly, and have a live run for 3 months or so to gauge if you actually need one. 

Youll need a PRedV anyhoo which should smooth out the spikes ( flush valve closing and 1/4 turn taps being closed abruptly ) but even a small accumulator will significantly improve the delivery characteristics of such a healthy supply, ( and would facilitate having a higher set pressure at the reducer ). 

Having 30-50 litres of 'buffer' would be a good medium imo, so basically two showers running simultaneously and no noticeable drop in pressure when the aforementioned get used elsewhere in the property. 

The zimlet ones from PumpsUkLtd are robust and reasonably priced. 

My gut feeling is you will live without it. ;)

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I think that my main design axiom is Keep it Simple Stupid (KISS) wherever possible, instrument and add the complexity only when needed.  In this case, I think that I should allow for the retrospective fitting (if necessary) of something like the 100ltr Zimlet, which is 450mm diameter and 960mm tall in its vertical config.  

 

I know the SunAmps have an  internal Expansion vessel, but I am going to have to do the sums and include another small one for the system as a whole.  This will be essential if I don't have the Accumulator from day 1.   Thanks again guys.  

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21 minutes ago, Nickfromwales said:

The SAPV EV is for the primary side of their PHE is it not? 

 

 

Yes, almost.  There is no primary side, but because of the arrangement of NRVs there is effectively a pressurised loop inside that needs a small EV.  The NRVs are to allow recirculation through a loop of the main pipework when charging, without needing flow through the unit.

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30 minutes ago, JSHarris said:

 

 

Yes, almost.  There is no primary side, but because of the arrangement of NRVs there is effectively a pressurised loop inside that needs a small EV.  The NRVs are to allow recirculation through a loop of the main pipework when charging, without needing flow through the unit.

Thought so. 

@TerryE, why do you think you need additional expansion? You'll have a lot of hot pipework for that. 

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On 06/02/2017 at 14:04, Nickfromwales said:

Why do you think you need additional expansion?

 

To be honest I don't.  As Jeremy says the SunAmps essentially have a couple of Phase-Change Material (PCM) cells that the input DCW flows through to exit through a TMV at a controlled temperature, up to 65°C max.  There is a recirculation loop used to pass water through the internal inline heater an the cells, and couple of check valve to ensure that there is no reverse flow to the supply and to prevent this loop acting as a bypass.  There's a good figure in the manual which explains this, but since it is copyrighted, I will only include it here with @Andrew Bissell - Sunamp's permission.


The small internal expansion vessel is to accommodate in-appliance expansion. External to the Sunamp I have about 1 ltr of water within the copper plumbing to the manifolds and another 4 ltr in the HEP20 DHW pipework.  So I need about 30 ml of expansion capacity assuming that we heat everything up, though in reality the figure is closer to 10ml which the HEP2O could accommodate -- ignoring the fact that either of the 2 SunAmp 500ml EVs could also accommodate this.

 

So really the only reason that I would add one would be just in case the BInsp would expect to see one.

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Ok, I'm still lost. 

Inside the SunAmpPV's you have a recirculating loop which heats the primary side of a PHE, yes?

The EV inside the SAPV is therefore not going to lend itself to the DHW circuit in your property.

20 minutes ago, TerryE said:

ignoring the fact that either of the 2 SunAmp 500ml EVs could also accommodate

If I'm right in my assumption above then the previous is incorrect. Or I'm wrong and the primary is sealed and copes on its own with the EV being on the secondary side of the PHE, in which case I'll shut my mouth :ph34r:?

@JSHarris can you clarify, unless @TerryE is in a position to do so?

 

 

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@Nickfromwales The PCM cells in the SAPVs do contain internal PHEs, but this isn't a conventional PHE with primary and secondary sides.  On one side is the phase change material (PCM) and water on the other.  There is only one water path and that is the potable DCW to DHW.  The 500ml expansion vessel is on this, and the only active device between this and the DHW output is a TMV.  I've emailed you the diagram that I referred to.

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FWIW, I think that the arrangement of NRVs inside the Sunamp PV, to effectively isolate the inner loop when the heater and pump are on and there's no DHW flowing, is pretty clever.  Nice and simple, with no motorised valves.  I like elegant and simple design like this!

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1 hour ago, TerryE said:

@Nickfromwales The PCM cells in the SAPVs do contain internal PHEs, but this isn't a conventional PHE with primary and secondary sides.  On one side is the phase change material (PCM) and water on the other.  There is only one water path and that is the potable DCW to DHW.  The 500ml expansion vessel is on this, and the only active device between this and the DHW output is a TMV.  I've emailed you the diagram that I referred to.

 

Well, I'm a man of my word.....

I'll shut my mouth. :D.

 

For everyone who didn't know, I asked.

Bingo.  

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