Unvented cylinder flow rate requirements?

[Ben10]

Hi guys.

Just a quick question. I've been asked to fit a Worcester Greenstore unvented cylinder but I'm worried flow rate is insufficient. I measured the flow rate at 14 L/PM. It currently comes into the house in 20mm mdpe and goes straight to 15 mm after the stopcock to supply the house.

I would fitting new 22mm mains pipework to supply the cylinder. What effect would this have on the flow rate/pressure?

It's a whole house refurb so all new pipework and new boiler/cylinder. They currently have a traditional set up in place.

Cheers.

Ben

 

[ShaunCorbs]

Take the flow reading from just after the stop tap but agree flow atm is too low

What's the pressure like ?

 

[Ben10]

5 bar of pressure at the mains stopcock.

Flow rate varies between 12 & 14 l/pm

We currently have 20mm mdpe going into the stopcock and then straight into 15mm

I am planning on replacing the 15mm pipework with 22mm. Will this give me a better flow rate? And should I upgrade to 25mm mdpe?

Also would a cold water accumulator work to increase the flow rate?

Worcester say the min requirement is 1.5 bar with 56 l/pm flow rate.

 

[ShaunCorbs]

Straight after the stop tap your getting 12-14lpm?

 

[townfanjon]

56 l/min lol , you sure . Are you G3 .

 

[Ben10]

12-14 ppm from a washing machine point located next to the stopcock.

 

[Scott_D]

12-14 ppm

Whats the ratio?

 

[ShaunCorbs]

Phone the water board up and ask them what's the pressure and flow in the street / what should you get

 

[Robert Tyrrell]

Hi guys.
I measured the flow rate at 14 L/PM. It currently comes into the house in 20mm mdpe and goes straight to 15 mm after the stopcock to supply the house.

I've just read the Greenstore installation instruction and I've extracted the following:
In a domestic installation, 1.5bar working pressure and approximately 15/20 litres/min. should be regarded as the minimum. Consideration should be given to upgrading existing 1⁄2" (15mm) cold mains pipework to a larger size, if the recommended minimum working pressure/flow rate is not being achieved. Maximum pressure is 5.5bar. Therefore I would recommend increasing the internal pipe size (Stopcock to UVDHWC) to 22mm.

From reading the post it does appear as though you have very little experience of G3 installations so my advice would be to either take your time and read the MI completely, or get yourself on a refresher course for G3 - it'll only cost you around £150 for a day and you'll have the knowledge you need to feel confident with this kind of install.