I'm renovating a cottage. We're geting a pressurised unvented hot water tank run from an airsource heatpump fitted by an installer, but I want to do the rest of the plumbing myself.
We're planning three en-suites, each with shower, basin and toilet. One will have a bath as well. Planning to run all the showers off the pressurised hot and mains cold.
The cottage is 10m end to end and 5 m wide.
The ensuites are at the extreme ends and the hot water cylinder is downstairs in the centre of the building.
The longest run will be 6m from the tank to one ensuite and then a further 5m on to the kitchen.
The next longest will be 6m and then a further 3m to the ensuite that has the bath.
My question is what size pipes should I use? 15mm or 22mm. I was planning to use plastic piping.
For the hot supply I will have 22mm from the tank for the first 600mm of so, but after that, do I reduce it to 15mm for the whole house? Or should I do the first limbs in 22 and then drop down to 15?
For cold, should I be running 15mm or 22mm from the stopcock?
All suggestions gratefully received.