House Renovation - DHW, CH & Everything Else Wet!

[SelfBuildSmurf]

Afternoon all, I've been browsing the forums for a while, messaged a few users direct but as we are fast approaching water tight I'm after a steer from the group on all things plumbing......

Attached are a couple of pictures of what will be the finished ground and first floor plans.

 

The existing house is/was

• heated using a warm air boiler (located in what will become a snug) ducting through floor to ground floor rooms and into the loft and into 1st floor via ceilings.
• hot water was previously provided by an electric hot water cylinder (i know $$$) located on the first floor. (Cold Water tank in the loft)

 

Mains gas and water come into the house in the snug (it used to be the kitchen). The intention is to re-route the mains water/gas to a plant room accessed off the garage which will house new

• System Boiler
• Unvented Cylinder
• Water Softener

 

Heating will be provided by

• radiators in bedrooms, snug, study (8 Rads)
• towel radiators in bathrooms/ensuite (4 Rads)
• underfloor heating in open plan kitchen/living room and porch

 

This will be a completely new plumbing system with all existing plumbing decommissioned as the job goes on as we are still living in the house as while work progresses. The first floor joists run side to side (across the front) of the house, except the rear extension which runs front to back.

 

Up until last week I was intent on using a branch/tee plumbing system for the hot water and central heating (because that's what I was familiar with) but I then realised how much more common the manifold systems have become. I've plumbed in plastic before when renovating our last house and I like the idea of using a manifold system because it gives a continuous run of pipe to the appliance/rad (reducing scope for leaky fittings at junctions/turns etc) but I also note the issues with having to empty fairly long sections of pipe before it receives hot water, to give an idea of scale the house is about 12m wide 14m deep.

 

In terms of design my questions to you lovely people would be, should I 

1. Use one manifold in the plant room to serve CH pipe runs to all rads and towel rails and secondary manifolds serving the UFH?
2. In respect of DHW and CW run a feed to each bathroom and install a manifold in each bathroom (therefore a using a shower means a significantly shorter length of pipe needs to be vacated for the sink hot tap)?
3. Is running a manifold off another manifold a no, no in terms of maintaining consistent water pressure etc?

 

In terms of manifolds etc, I'm familiar with 15mm, 22mm etc. but I'm seeing reference to 10mm, 16mm across some brands.

• Is there a preferred brand of pipe, manifold etc. you would recommend?

 

I'll probably have more questions as we go on but I am actively scouting threads looking for answers etc. so thank you in advance for all the contributions