Whilst I agree with many of the advantages, I'd say not everything is
entirely true.

- High mains water pressures at up to 10 bar, compared to 3.5 bar with
unvenetd cylinders.

DPS seem to want a pressure reducing valve if static pressure is above 6
bar.

- Very high water flow-rate - The high-end heat-banks have a flow-rate up
to
45 litres/min.

Whilst very good, unvented cylinders will supply more. (i.e. Megaflo claims
72 lpm)

- Cold water storage eliminated - No need for cold water storage tanks.

A header or expansion tank is needed for the vented heat bank store. This is
frequently combined with the store itself in a combination cylinder, but
this requires additional head room.

- Lower water temperatures with fast flow-rates - As with Combi boilers,
fast flow-rates through the plate heat-exchanger results in lower water
temperatures. (...) This also applies to unvented cylinders (...)

Could you explain how increased flow rates decrease water temperature with
an unvented cylinder? The limit on flow rate with an unvented cylinder is
how much water you can shove through the thing, presuming a good design on
the water inlet that doesn't unduly disturb stratification. Obviously, if
you draw at 75lpm, a 150l cylinder will be cold well within 2 minutes (but
then you've already filled close to 2 baths by then).

No so. They can operate up to 10 bar pressure. Unveneed cylinders can only
operate up a typical 3.5 bar.

Again, the only heat bank I've got details for (DPS Pandora) claims 6 bar.
However, the pressure reduction isn't as bad as it seems. Obviously, as
water is drawn off, the pressure falls massively. So even if your static
pressure is 6 bar, drawing 75lpm will cause the pressure to collapse below 3
bar, meaning the pressure reducing valve is fully open, and only providing a
restriction in line with the reduced bore of its opening, probably
equivalent to a 90 degree elbow or a few metres of pipe.

Christian.