Yup, the blanked supply is the balanced feed so anything that is using an in body mixer for hot and cold (monobloc taps/mixer showers/etc) should be fed from that supply to ensure the outlet is balanced.
You may want to take a pressure reading on the hot side to see if the PRV is working/set correctly as per the Unvented MI. If it isn't though it really needs a qualified engineer to fix.
As @ianmcd mentions though are you talking about the pressure at the hot outlet or is it the flow, they are separate things.
If they are in body mixers and aren't balanced then the hot can be held back by the higher cold pressure.
You may want to take a pressure reading on the hot side to see if the PRV is working/set correctly as per the Unvented MI. If it isn't though it really needs a qualified engineer to fix.
As @ianmcd mentions though are you talking about the pressure at the hot outlet or is it the flow, they are separate things.
If they are in body mixers and aren't balanced then the hot can be held back by the higher cold pressure.
