Water balance issues since going over to an unvented cylinder

[Robbot]

A year back I had a new unvented cylinder installed to replace an old vented one. As you can see from the attached diagram, no balanced cold feed was taken from the back of the PRV. The cold feed that supplies the kitchen and bathroom remains as before, and the fitter took the existing feed to the loft tank for the cylinder.

When the bath is being run, the kitchen taps dripple and Vice versa. It appears as if there is not enough flow. The PRV was checked during a recent service and was found to be fine. Any ideas?

 

[oldbuffer]

1. Did you have the incoming mains water pressure and flow rates measured before the installation. If so, what were the pressure and dynamic flow rate readings?
2. Do you know the diameter of the cold water pipes?

 

[Robbot]

1. Did you have the incoming mains water pressure and flow rates measured before the installation. If so, what were the pressure and dynamic flow rate readings?
2. Do you know the diameter of the cold water pipes?

The installers didn't make those checks. However, Anglia Water took a measurement a few years back (before the unvented tank install) and they said it was just over 3 bar and normal for the area.

The cold water pipe is 15mm from the stopcock to the kitchen tap, bathroom tap, and cistern. Then just before the PRV it has a small section of 22mm. Hot is 22mm.

I did measure the flow prior to the install as I was trying to balance a shower system with the old vented tank. I cant remember exactly what it was, but again it was within a normal range.

I gutted, and fitted a new bathroom a year before the unvented tank went in. I replaced all the pipework under the floor and never had any issues with the cold balance between all the taps. I was looking forward to having a decent balanced shower with this install !