pressure accumulator

The rising main in my downstairs bathroom looks like galvanised steel- 27mm by my measurements, which eventually joins to 15mm copper in the kitchen. I'm looking to tee off somewhere to feed an unvented cylinder, so need the best flow rate possible. My question is, would the flow rate be better...

Hi, I had a new heating system installed in my flat to replace an archaic gas fired warm air heating system and a gas fired water boiler in my kitchen. I had it installed in my loft on the gable end with new pipe work and rads. I also had a pressure accumulator fitted due to the mains pressure...