I currently have a 4 bed house with a Potterton Profile 50 powering a
Gledhill Boilermate which is about 15 year old. Having extended the
house a couple of times, when the heat is on full blast on a cold
morning, the first shower is fine but a consecutive shower runs cold.

Household is 2 adults and 2 kids, one being a pre-teenage daughter who
loves long showers :-( . We have 2 bathrooms - one bath and two high
flow showers.

I'm intending to replace the boiler with a condenser but the hot water
issue is the difficult bit. I have read the various ramblings on
unvented v heat stores and I'm still unsure as to which way to go.

The current thermal store has worked well so I'm not scared of the
heatbank option, but DPS quoted me =A3945 for a 180L Pandora which
wassignificantly more than the 210L Megaflo.

I like the Powermax for its compact design, but I'm concerned that I
can't find any solid recommendations for it. Also I'm told the
servicing is tricky. Does anyone have any experience of these?

Taking the separate boiler/cylinder route, I like the DIYability of the
Heatbank and the associated safety. Is there any way I can go down this
route for less money, or should I look at unvented?