Many thanks to Andy Hall and others for their help earlier this year on the
design of my new plumbing system (http://tinyurl.com/3pwck etc.).
Unfortunately, thanks to a few months illness, I'm still at it - with a few
issues to resolve.

A question regarding an unvented domestic hot water system: Cambridge Water
tested my incoming main supply and informed me that the pressure = 2.8 bar
and the flow rate = 25 litres per minute. Is this sufficiently high for an
unvented supply feeding a family home containing two power showers, a bath,
five sinks, three toilets, a washing machine and a dishwasher?

My feeling is that it isn't. At worst, I would guess that only one shower
and the bath would be running concurrently. Even so, a power shower consumes
15 lpm and a bath consumes 20 lpm.

Is there any way around this problem? A pump and hydraulic accumulator
sounds expensive. Due to a loft conversion, there is not any convenient
space for a cistern, although I'm thinking that I may have to create some...

[For information, the hot water will be heated indirectly in a 250 litre
tank by a condensing boiler. The mains supply pressure will be reduced (to 2
bar?) by a water softener, although a "high flow" softener, such as the
Kinetico 2020c HF, will be fitted to minimise this problem.]

Presumably the central heating could operate as a sealed system, even if the
hot water tank is vented?

TIA