install new central heating system

[hayati]

Hi All,
I am very new to all this so forgive me if I am lacking alot of knowledge. Aiming to install a new central heating from scratch.
Property details

• split over 3 floors
• 4 bedrooms
• 2 bathrooms
• open plan kitchen/lounge

Current Installation assumptions

• install 8 rads in total running off a combi boiler
• 15mm plastic

Question

• as it is split over 3 floors does it make sense to have zone valves for each floor?
• do I need an additional pump to cover the 3 floors? additional expansion vessel?
• Planning on using 15mm plastic, should I be considering 22mm instead?

Attached is a photo showing the layout I plan to run the central heating pipes. Any advice would be appreciated if it looks wrong.

Many thanks

 

[ShaunCorbs]

As it’s from scratch/ new you will need to bring it upto current regs eg new rad sized for 55dc flow and 28mm pipework

 

[Last Plumber]

You need heat loss calculations first of all. Done by a tried and tested, accurate method.
You will need to size heat emitters correctly to give the right output at 55 degree flow (as Shaun said). See part L of building regs.
You will need to calculate the pipe size going off route and volume of water to be carried, pressure losses etc.
You will be better off with 3 zones in my opinion. Each with its own controls.
You will usually size the pump off the above findings and may need to adjust things to suit. With a combi boiler you need to know what is left in
15mm plastic is only capable of around 20,000 Btu but that depends on things like route, fittings, valves etc. It can be less.

Hope this helps.

 

[king of pipes]

Its not the sort of job for a novice you would be far better off employing a professional, your plans contain errors already pipe sizing is very important heating over 3 floors will require 28 mm flow and return for a good few meters , a combi boiler is really only meant for smaller properties hot water supply is limited to one or two taps at best. . Kop

 

[hayati]

thanks all for the feedback. looks like its not as straightforward as I hoped. lots more research to do then and I'll see if I can get an experienced plumber to work along side

 

[king of pipes]

That's a fair better idea or costly mistakes will be made . Kop