what replacement central heating

[oldie]

I have an old 30 year Ideal E-Type boiler supplying a vented Hot water tank and then radiators via 8mm micro bore. The boiler is now failing and the 3 port switch lets CH and hot water passed it with the lever at the left as you look at it.
So although I am 73 I feel I need to replace this system, which I will get a central heating person to do. However I would like to let him know what I feel I would like as the replacement.
So my questions are:
I want an intergas boiler that I intend to move from the utility room to a small loft above.
I want to put the hot water cylinder in the large loft (It’s in the upstairs cupboard at the moment) do I specify something like the Fortic F3 indirect combination vented unit which has a cold water tank attached on the top so I can do away with the old plastic cold water tank or is a sealed system a better bet?
I hate the 8mm connection to all the radiators from a manifold upstairs but my wife doesn’t want 15mm pipe coming down the walls downstairs. Will 8mm be sufficient to keep us warm as the old system is not very hot?
My present hot water tank has a backup heater element that is powered by my PV system and I wish to keep this option.
Do I need to change the radiators?
Sorry so many questions but I don’t want to get it wrong and I’m not an expert like you lot.
Alfie

 

[Agile]

Why not just call a local Intergas listed engineer to quote and advise you.

8 mm is not very ideal as it blocks so easily!

Tony

 

[dcawkwell]

Combi boiler sorted.
Sealed system.

Don't like intergas myself as asking about any train courses for their
boilers they couldn't even be bothered to reply.

 

[Agile]

You should be rating the boiler and not their useless customer service communication.

Probably caused by the previous boss not wanting to employ more than about three people!

They did give me a mug and a pen when I went there. No teeshirt though! Even Alpha gave me a teeshirt!