"Dave Liquorice" wrote:
On Sun, 26 Jun 2011 14:06:56 +0100, Steve Firth wrote:

I can't fault the product, it's excellent. We have a 300 litre Xcel unit
that provides points for underfloor heating, radiators, and a heat
exchanger for mains pressure hot water. Inputs are taken from an LPG
boiler, solar panels and a wood burner in the kitchen.

What output to water will the woodburner give you?

I'm considering a 12kW woodburner with 6kW estimated to the hot water.

I'm in the
planning stage of a very similar setup (s/LPG/oil/ and
s/kitchen/snug/). The woodburner I'm looking at will give 6kW normal
(8kW flat out) to water, I'm thinking that a 300l tank is a bit small
and will overheat rather to easiyly.

I don't think so. I have a standard DHW setup with a log burner of similar
size. I've never had it boil even when blasting it with heat in winter. I
expect to have a diversion valve and a radiator as a heat dump when the new
log burner is installed.

But one has to balance that against getting a sensible raise in store
temp from just the solar though. I guess when the wood burner is on
the house will be demanding so maybe overheat of the store in "normal
use" won't be an issue. Doesn't the DPS use a passive thermal valve
and a mains water dump to cool the store in extremis,

Not mine, but it is an option.

normally it just runs the CH pump to loose heat.

That's the only option that I have.

The DPS Xcel looks good but I think I've said before I don't like the
external plate heat exchnager for DHW I'd rather that was a coil
within the top of the store like the Akvaterm ones.

I went for the DPS because of the tech support which is outstanding, the
high output of the plate heat exchanger, and the fact that the exchanger
can be changed if necessary.

It's working well with a 30kW boiler. No sign of short cycling and after
the first test firing to 70C the temperature in the store held at 60C until
late the next day.