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On 27 Mar, 14:04, "Clive" wrote:

Hi,

I have bought a small two and a half bedroom end-of-terraced
Victorian house. It has gas central heating with a floor-standing
boiler that does the job. The boiler could be 20 - 25 years old. The
system has a hot water tank with a jacket that seems as thick as a
cardigan. The system supplies loads of hot water and some of the rads
are absolutely scorching. I'm sure the rads could do with a "re-
balance". I feel it is all very inefficient in fuel terms but it works
and will cost a pretty penny to replace.

I'm thinking about doing / getting done kitchen, bathroom and
loft.

I would like to stick some "wet" solar panels on the roof, even
if
they don't pay off financially, so I feel I am doing my "bit" for the
environment. OK, money does come into it - see below.

At most, the house will be occupied by one or two people. So here
is
the idea. Replace the boiler with a condensing combi boiler. Then I
get hot water "on-demand" and at mains pressure. I don't heat a tank
and then let it cool for hot water I never use. I had a Vaillant combi
boiler in a one-bedroom ground floor flat and (apart from the
occasional wobbly) it would chuck out hot water at mains pressure
within seconds. I want to retain that and avoid shower pumps and
electric shower heaters.

The "clever" bit would be to have a hot water tank but only use
it
for the central heating. It would have two supply circuits, one from
the wet solar panels on a south-facing roof - this would "pre-heat the
water. The second supply circuit would be from the boiler. The idea
being I could collect as much heat as possible on a sunny day on the
solar circuit and top it up with gas-heated water. The tank would need
to be well-insulated to store the heat from a sunny day and release it
in the evening.

Could such a setup be installed and would the heat gained from
the
panels be worth the expense of the installation? Is there anyway of
making a rough calculation on the heat / temperature gain to work out
the money saved on pre-heating the water in the tank?

Thanks

Clive


As David explained, you cant lose the water storage and go solar - not
unless you put in solar batch heaters, which are storage and panel in
one.

Combis are not something to choose unless you have no other option.
Performance is poor.

A big storage tank would enable boiler heating of the top half, vacuum
tube heating of top half, and flat panel heating of bottom half.

Some more info:
http://wiki.diyfaq.org.uk/index.php?title=Solar_Thermal

Another good payback energy saver is
http://wiki.diyfaq.org.uk/index.php?...Heat_Exchanger

And of course you need proper tank insulation.

With a heatbank you dont need to replace the tank, as an inbuilt
exchanger isnt needed.


NT


I will say it again, very simple system, using a Geldhill Torrent RE Thermal
Store. see www.gledhill.net for more info.

--
Regards

Stephen Dawson
Fox Electrical Services Ltd
www.foxelectrical.co.uk