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Another DHW / DCW / UFH design


TerryE
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Do I dump my PRedV?  This is the Q that I am asking myself. 

 

I've been monitoring our mains pressure over the last week or so.  It only varies by a gnat's arsehole off 3.1 bar.  Where we live is gently rolling Northamptonshire.  Anglian have to pump/boost the pressure (I suspect to a target 3bar at the top of the village and we are ~1.5m below this height, hence the 3.1 bar).  Our water softener spec requires us to fit it in front of the PRedV except where the mains is over 5 bar in which case you are required to have a second PRedV set at 5 bar in front of it.   I've pressure tested the system to 7 bar -- except the SunAmps to 5 bar because I don't want to blow their internal PRelVs which are triggered at 6 bar. 

 

With the Harvey Filter, the SunAmps and Double Check valve and the TMV, the main risk is going to be achieving target flow rates. With a 3 bar mains, the PRedV serves no useful purpose, so why not dump it and avoid the ~0.3 bar pressure drop that it causes at normal flow rates?

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I'd be inclined to dump it, if it were me.  They do cause a reduction in flow rate that was quite noticeable when I took ours out.  I put it in originally because we were running the borehole pump at around 4.5 bar, but left it there, set to 3.5 bar when I reduced the water treatment plant operating pressure.  TBH. I didn't notice the flow reduction it was creating until I removed it, when I took out the thermal store and fitted the Sunamp PV, it was the improvement in flow rate after I removed it that was noticeable.

 

As an aside, I've found that fitting flow rate reducers on all the taps, except the bath, has not only made those taps more user-friendly (less splashing and easier flow control) but it has also reduced the impact on the shower flow rate when a tap is turned on to the point where it's virtually undetectable.  It wasn't my choice to fit these flow restrictors, it was a building regs requirement to comply with the water usage bit of the regs, but if I was starting again I'd fit them as a matter of course to all the non-flow critical taps..

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I guess the question really is do you EVER see higher static pressure than the 3.1 bar ?

To gauge this, I'd fit a gauge and a NRV so whatever the peak network pressure is will be captured on the gauge. 

Have you already done a 24 or 48 hour constant connection to get this result ? Network ( static ) pressure rises and falls with local area consumption, so, for eg, when surveying for an accumulator the best practice is to see how high the overnight charge will get to before sizing and quoting. 

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2 hours ago, Nickfromwales said:

I'd fit a gauge and a NRV so whatever the peak network pressure is will be captured on the gauge

 

Done this -- by accident as it happens -- yup, somewhere between 3.1 and 3.2 bar.  The village used to be fed off a water tower in the next village ( @Vijay is building his house in its shadow.)  Now it comes from a small buffer reservoir 1½ miles in the opposite direction which is only 10m or so higher than the village and so is pumped. 

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12 minutes ago, Nickfromwales said:

I'd fit a 5 or 6 bar cold mains prv as a failsafe if it were me.

 

Nah, I'll live dangerously and put in a pressure transducer as Peter pointed at and rethink if I start getting supply readings over 4 bar.

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3 minutes ago, TerryE said:

 

Nah, I'll live dangerously and put in a pressure transducer as Peter pointed at and rethink if I start getting supply readings over 4 bar.

By the time you get the reading, the 'damage' would be done. 

Thats why they're mandatory on a multi-block / control group for an UVC. ;)

SAPV's aren't cheap, a PRedV is ?

For £15 I'd want to cover my install. 

Just saying ;)

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2 minutes ago, TerryE said:

The SunAmps have 6 bar PRelVs in them that look very much like your link and as I said, I've taken the main system up to 7 bar.

Bugger. Forgot about those. 

Any sensitive stuff between the stopcock and those? Softener is, isn't it?

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Seriously Nick, I was going to put in a 5 or 6 bar PRelV until I realised that the Sunamps each had one in that would be easy to replace so why bother? 

 

The installation guide for the Harvey explicitly states that the 3 bar PRedV should be fitted after the softener and that a 5 bar PRedV should only be fitted n the supply side if the supply rises above 5 bar.   The Harvey is tested to 6 bar, so the risk if Anglian decides to double the pressure is that the SunAmps PRVs go.  Oh, yes and all sorts of leaks will spring up throughout the village supply which has never been stressed to this level and ditto most of the houses in the village.

 

It's a risk that I'll accept. :)

 

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Potable water all plumbed up (apart from one pipe section which has been cut to length and fitted but not as yet soldered up).  Time for a glass of wine intervened.

 

To give you a sense of the size of the water services area, the two SunAmps on the left are hard against the LH wall and the Harvey water softener on the right hard against the right one.  You will see from the picture below that I've still got to add the loop between the manifolds, Willis Heater and PHE, plus the expansion vessel / fill system for the UFH, but that's tomorrow's job.

 

I've designed the connections to the SunAmps so the two SunAmp units can be isolated, disconnected and removed or swapped, so I can always take one out for maintenance.  @Alphonsox, also note the two flow meters on the feeds into the SunaAmps.  This flow and the temperature rise will together tell me how much (and when) I am using DHW. 

 

I've also gone to great lengths to minimise or remove any unnecessary bends on the main water paths.  The manifolds on the left pic are the DHW so I will be boxing these in.

 

ServicesUpperShelf.thumb.jpg.7bf2bf680f40c31e2122c268fc9ece8d.jpg58c1a2d5ebd3e_ServicesBelowShelf.thumb.jpg.7f8e5c2afda3a691ed59ae83f012d1ad.jpg

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All potable water plumbing pressure tested today.  TaDa!! 

 

I've got about 30cm (of the 2m coil lead-free solder that I bought) left so it's touch and go as to whether I will have enough to do the last UFH copper loop, so I might still have to do some lead soldering, but this is for the UFH so that's allowed. :)

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When did you buy your manifold.  I've got the "premium manifold" which is the one that they are selling now on the Wunda website.  This uses one of the port pairs for the two filler / drains.

 

Is your manifold the previous generation?  If looks as if the filler / drains on your are for left hand mounting and isn't listed on the website.  Which pumpset have you got?  Is it the one which can be mounted on either side?  If so then one option would be to reverse the flow direction, that is have the pumpset on the right.

 

Mine is designed for left hand mounting only.

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It arrived on Thursday ..! It's the premium manifold but the ESBE valve is only good for up to 5 ports. 

 

I'm also in discussions with them about getting the 20-43c blending valves into stock for low temp floors. Watch this space ..

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On 12/03/2017 at 20:08, TerryE said:

So here is the UFH setup.  There's one fill line missing; I was just about to fit it but Jan ordered me in for dinner.   The Wllis heater is in between the UFH and the PHE.

58c5a9c8a5172_ServicesBelowShelf2.thumb.jpg.cfcc85778fb2148c29996b07e7823b39.jpg

Does it matter if the expansion vessel and fill loop is on the flow or return (like you have) or does it make a difference? Any advantage to either or is it whatever is easiest?

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16 hours ago, Dudda said:

Does it matter if the expansion vessel and fill loop is on the flow or return (like you have) or does it make a difference? Any advantage to either or is it whatever is easiest?

 

IMO No.  I wouldn't expect to fill it with the pump running anyway.

 

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