On Tue, 16 May 2006 08:36:11 +0100, David Hansen
wrote:

On Mon, 15 May 2006 23:36:55 +0100 someone who may be Peter Parry
wrote this:-

Actually it is a long term non-investment as in most cases, and all
commercially installed and maintained systems, it will never even
break even.

At current prices DIY systems are long term investments. Systems
where one pays someone to install it are probably not going to break
even at current prices, but note the name of this newsgroup and that
the price of sunshine is not going to increase, unlike other fuels.

If it proves popular what's the betting ownership of it will get
taxed (indeed the mechanism for doing so has already been put in
place by Nulabor) :-).

There are also other advantages, such
as being able to largely turn the boiler off in summer and thus
(probably) prolonging its life.

There is no evidence that this is the case at all,

Incorrect.

I'd be interested in seeing any. The only mentions I have found are
unsubstantiated statements usually made by peddlers of solar
fittings.

and in all
probability it will almost certainly reduce its life as seals and
bearings in pumps

Pumps should indeed be turned over occasionally. However, that has
no bearing on the life of the boiler.

and valves really dislike being unused for months on end

No bearing on the life of the boiler either.

Both have bearing on the life of the "conventional" system and hence
the economics of solar water heating. In many boilers the pumps and
control valves are integrated within the boiler.

and corrosion will also worsen.

Corrosion where?

The boiler casing. It is a fairly common cause of terminal failure
of room sealed boilers.

Environmentally solar water heating is an excellent investment.

In propaganda.

Incorrect. As I pointed out and you snipped, it can save more gas
than people think.

I snipped the bits about saving energy (which I agree is a far more
sensible starting point and applicable no matter what system is used)
but didn't see anything about how solar heating can save more gas
than people think.

You can keep trying with your incorrect assertions for as long as
you like. However, because somebody may believe you, they will be
rebutted whenever necessary.

So will unsubstantiated and incorrect claims for solar water heating
making economic sense. People may buy it for other reasons not all
of which may be altogether objective and that is their free choice.
What is wrong is to claim it makes _economic_ sense when quite
plainly in the vast majority of cases it doesn't (which of course is
exactly why the proponents of it always studiously avoid using
figures).

For example the oft quoted solution of the solar powered motor pumped
panels on the direct side of the water system makes great claims
about the economic sense of doing this (saving the few watts an
electric pump takes) but makes little or no mention of the fact that
for most people living east of a line drawn roughly from Lincoln to
Bristol you also need to install an ion exchange water softener
otherwise the panel will quickly be ruined because of scale from the
hard water.


--
Peter Parry.
http://www.wpp.ltd.uk/