Pipework for multiple showers from a heatbank.

[davecph]

Hi I’m new to this forum so any help is most welcome. I’m installing a completely new heating plumbing system in a domestic referb, and could do with a tip or two on running my pipework to multiple (3-4) showers to minimise pressure fluctuations. I’m beginning to think my design is a bit OTT. Can someone please advise if I’m on the right lines, or can I simplify the circuits & installation cost. I need it to be right as I’m only doing it once, cost is less important, having just spent £2K on a HeatBank.
I have just over 35lt/min at 7 bar incoming, via 25mm pipe directly to a DPS heatbank from the stop-cock. Just before the tank I recon to spur off for cold to sinks etc etc , and put a pressure reducer set to say 3-4 bar for this part of the circuit. Another reducer set to 6 bar (max capacity for the heatX) goes both into the HW side of the plate heatX and a 2nd cold spur to feed only the showers. One question is; do I need yet another pressure reducer on the spur, after the heatX to supply hot to only the sinks, leaving the shower hot supply pipework dedicated at 6 bar, (less the pressure drop across the heatX)? This means I have dedicated H&C to sinks at 3-4 bar and 6 ish bar to the showers. The next consideration I have is the dedicated piping to the showers. Should they be run independently from the origin (ie parallel circuits,)or can I run 15mm pipe in series without one shower upsetting another? I don’t want to use 22mm if possible as it will take a long time for the hot to get through each time the shower is used. There are three showers with normal cheap mixer valves & small shower heads, (with a 4th planned next year). The mixers are probably only 5-8 lirs/min each not much more. (I don’t believe in using masses of water in a “power” shower as they consume too much energy). I have a new 26/36KW boiler serving the heat bank & solar of course. The plate heatX is rated to 45lt/min, more than I have available.
All in all I seem have a lot of separate pipes running from the heat bank. Perhaps there is a better way? On the other hand this might be the setup needed when a car full of wet, cold Cornish surfers arrive and all need a hot shower quick!
Many thanks in anticipation.

 

[Norcon]

Shower valves usually have max limit for pressure specified. Mira excels are 5 bar!

I set the incomer prv to 4 bar and the UV to 3.5 recently.
Its working well with 4 showers and two of them are rain heads.
The prv's are in series although the 4 bar one supplies a separate area of the property. Pipework starts in 28mm>22mm>15mm.
Two adults and six children occupy the residence.

 

[davecph]

Many thanks for responding. You raise a good point thanks, I hadn’t considered the max pressure for the shower valves. I will check it out and set the shower circuit prv accordingly and then set the sink circuits below that to give some headroom to prevent pressure fluctuations form the sink taps.
I’m not sure what you mean by “the UV”? Is it a “Mira Universal Variable Water Delivery System”? They look a bit good, but I’ve already got ordinary bog standard mains pressure thermostatic mixer valves for each shower.
When using 28>22>15 pipework, is there a considerable amount of cold to purge out before the hot arrives? Did you provide separate circuits for the showers and sinks, or are they all in the same circuit? If so, do you get any pressure fluctuation issues?

 

[Norcon]

UV is unvented cylinder.

A secondary return was installed to ensure hot water is close to the taps.
The 28mm section supplied the cold from the stop valve to the UV.

It's all one circuit. I only ran the system with three showers running and there was no noticiable fluctuation in flowrate to each individual shower as each one was turned on consecutively.
The guy seemed happy enough and moved in just before christmas and has commented since that his showers are brilliant.
He laid part of the mains pipe himself and dropped a size below that which I had originally recommended.

 

[davecph]

So, all in all, are you saying it is unnecessary to run separate pipework to each shower? What about the sinks, would you put them on a separate circuit in order to minimise pressure fluctuations?

 

[Norcon]

So, all in all, are you saying it is unnecessary to run separate pipework to each shower?

Yep.

What about the sinks, would you put them on a separate circuit in order to minimise pressure fluctuations?

No.
Size the pipe correctly and no need for separate runs. Ensuites or bathrooms in large properties have five pipes involved and I find thats enough.
Flow setting to individual outlets such as basins and sinks etc is important.
Shower restrictors are also available.

 

[davecph]

Thanks, this is looking good. I didn’t know about outlet flow restrictors. That will be useful to limit water usage and energy. It looks like I can also fit a Deva 7lt/min restrictor to all my sink mixer taps too.
As to “size pipes correctly” I can’t find relevant info for water pipework. Can you point me in the right direction please? I don’t want to use 22mm on the hot side. It has approx 3 times the volume of 15mm, so I waste more water each and every time I use the shower/sink purging the cold out. My pipe runs are relatively short max 5m from the tank and will be restricted to 5 bar max. The question I have is: do I get sufficient flow to run two showers and 2 sinks (all restricted to 7lt/min output) off a single 15mm, without pressure fluctuations?
I’m a little confuse with the 5 pipes, unless you mean H&C in; dividing into H&C for Shower & Sink + Toilet.
Many thanks for your help so far I am most appreciative

 

[Norcon]

do I get sufficient flow to run two showers and 2 sinks (all restricted to 7lt/min output) off a single 15mm, without pressure fluctuations?

It may well do!
I'd be piping this using 22mm to the first set of outlets reducing to 15mm supplying the second set.

Try here for pipe sizing..........
http://www.ukcopperboard.co.uk/literature/tipslist.shtml

The five pipes include H & C, secondary return and heating F & R.

 

[davecph]

Thank you that has been a great help. I can now get stuck into the installation with relative confidence.