Mains accumulator - will it work?

[fezster]

I've been thinking for a while now on whether a cold mains accumulator will resolve my "problem". I'll explain the setup:

 

1. 32mm incoming MDPE. Mains pressure > 4 bar (higher depending on time of day) and flow rate ~40-50 litres/min measured at outside tap.

2. 3 bar pressure reducing valve at the mains with an unvented cylinder for hot water.

3. I have three rain head type showers, capable of >16 litres/min according to the spec sheet.

4. Internal pipework is a short run of 28mm, then 22mm running through the house, with 22mm teed to each shower.

5. Running any one shower any time of day, the flow is great. Working pressure at the mains drops to 2.2 bar.

6. Running two showers, working pressure drops to 1.4 bar. This is where it gets confusing - depending on time of day, the performance of both showers is either adequate or pitiful (usually the latter in the peak morning time). However, the working pressure is always the same - 1.4 bar. I'd have thought with a lower incoming flow rate, the working pressure would also drop more substantially - but this isnt what I've observed (albeit, my method is not scientific, rather how I perceive the shower to be performing).

 

I searched the forum and see a lot of posts from people about accumulators and was hoping someone might know - is it possible to determine, beyond doubt, that an accumulator close to the incoming main would enable both showers to run to full capacity? A calculation, perhaps, based on the measurements taken?

 

I've invited Stuart Turner reps and plumbers but nobody seems to be able to say definitively whether it would work or not. The standard response I get is that my incoming flow rate is pretty amazing already, an accumulator won't help - which doesnt help if you want to run 3 x high performing showers at the same time.

 

[ProDave]

My concern is the bottleneck is the pressure reducing valve on the UVC and an accumulator in front of that won't help.

 

 

 

 

[fezster]

The Pressure Reducing Valve is 3 bar though. So given the dynamic pressures measured (< 3 bar), I dont think that is a bottleneck in terms of pressure.

 

If you meant in terms of pipe size restriction, the PRV is a 28mm reliance valve, so should easily handle in excess of 100L/min.