I will be looking for wall hung, condensing, good efficiency. Not Combi,
for a 4 bedroom house. vented fully pumped system.

.....are you a member of the flat earth society as well?

Dr Drivel
Can i ask what makes you say that?

It is not 1972 anymore.

Are you saying you would rather have a Combi?

Yep. They can deliver high flows and no cylinders or water tanks.

I will consider all options. (but not warm air, however good they are
now).

They are good and you don't consider? Sounds Irish. Oh That is racist, so
sounds err, well any race you don't like. Do you wear flared pants as
well?

What are the advantages of a Combi? I guess space as a hot water tank is
not required,

Yep.

but what are the others?

No cold tank.
Less pipe work.
Mains pressure showers, so no silly power shower pump.
You never run out hot water.
Can stay in the shower for ever.
Equal pressure at all taps, so mixers can be easily installed everywhere.
Instant hot water at all times.
etc,
etc,

I am not a jolly amateur. Come back if you have any more queries.

Sounds intresting.
With regards to this bit "Mains pressure showers, so no silly power shower
pump"

How does the system hold up, when someone is having a shower, the heating is
on & maybe someone is running the hot tap in the kitchen. This is all
hypertheticail of course. I'm just trying to think of the hardest thing the
system would have to do (or be asked to do). Or put simply. "Would it cope"
?
Regards, Will