H
Hot&Cold
fair point,different customers have different needs & demands. Every customer is differentIt's more about whether folk would go for combi & do a full refit or maybe opt for the system with lower pressure and use existing 1970s pipes?
Usually getting a heating installer (not a plumber) to visit & discuss what you want is how its done,they will have the onsite opportunity to walk your property and work out what is possible.
They can also do some tests on your incoming mains water supply if you want a combination gas boiler,we have no idea of your property or your needs & demands and i doubt google or will be of any help.
I think I'd be living here for about 10 years and want a system that will be useful for me and those who might buy a house from me later down the line...
Thats part of needs & demands but who knows what the next occupiers will want,i can say they will expect a recently fitted system to professional fitted and is suitable for the property.
lots of options