Pressurised Cylinder & Mains Pressure.

SMG · 30 Jul 2011

I have been doing some research on unvented, indirect, sealed pressurised systems. Most have control valves with a 6 bar relief valve & a 3.5 bar pressure reduction valve, apart from other various valves & controls.

My question is, does there have to be a minimum pressure for these systems to work? Obviously any excessive pressure will be controlled by the prv & Relief valve.

For example, my mains pressure is 2.5 bar, so, could this system be fitted at my home. I did anticipate a pressure well in excess of 3 bar on the mains.

looneyfitter · 31 Jul 2011

Pressure is important with this type of system. More so tho is flow rate. Do you have a standing pressure if 2.5bar or working? How long does it take to fill a 5 litre jug?

ChrisR · 31 Jul 2011

Watch for a restrictive kitchen tap when doing that test, an outside tap might be better.
WHat you're trying to establish is how restrictive the pipe is, from the road to the outlet.
2.5 bar is acceptable, but not if an old half inch lead pipe squashed at a few places, restricts the flow.
18 litres a minute into a bucket is about the point where it's getting in the way. 22 is better.
Or take 10 litres/minute, and measure the pressure at a different tap. If it's down to 1 bar you have a problem.

SMG · 31 Jul 2011

Water pressure is jjust 1 bar when running, 2.5 not running. 20 liters per min through a 15mm pipe.

looneyfitter · 31 Jul 2011

That should've fine mate. I take it your a normal house and not 3stories? What is your incoming main size? Material? If it's mdpe (plastic) you would be better changing the stop tap to a 22mm outlet and supplying the cylinder with a 22mm feed. 15mm is acceptable but 22 is better

SMG · 31 Jul 2011

Yes, semi det, but I had a new 25mm mdpe incoming feed fitted, (was old lead) from my own stop tap, to a new water main stop tap on the pavement.

I will change the 15mm to 25mm MDPE, then to 22mm copper, I was concerned about the pressure, is 1 bar too low?

looneyfitter · 31 Jul 2011

1 bar be fine mate. Upgrade to 22mm. The best would be to have each 15mm branch fed off a 22mm supply but not essential

SMG · 31 Jul 2011

Thanks, I was concerned about the pressure.

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Pressurised Cylinder & Mains Pressure.

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