On Wed, 17 May 2006 10:01:07 +0100 someone who may be Peter Parry
wrote this:-
The boiler casing (the outside box) doesn't have acid deposited on it
as it is only exposed to incoming air. It does get condensation and
damp from the outside atmosphere (to which it is open in a room
sealed boiler) when unused. As it is a spare part which is almost
impossible to get for older boilers corrosion on it often ends their
life.
Perhaps you have experience of boilers in corrosive atmospheres, the
seaside perhaps, but I have yet to see a boiler in a house suffering
from this alleged problem.
The "government report" also signally failed to mention that on a
cold sunny day with little solar gain the device also happily pumps
your gas heated hot water into a nice big radiator on the outside of
the roof to cool it down. What is the energy cost of this?
Already covered by
http://www.solartwin.com/technical_faq.htm
"Q: During the winter months when most of the hot water will be
generated by the boiler, what happens if there is enough sun to set
the pump in action. At which time there is not enough thermal energy
to heat up the water sufficiently so that when it is returned to the
hot water tank it reduces the temperature there?
"A: The pump runs only on solar energy in the form of electricity.
It has no temperature sensor, only a high pressure bypass in case
the panel or its pipes are frozen. In response to your question:
First - best not to have the hot water system on all day since this
is wasteful anyway and does not allow for optimum solar performance.
Most boilers have separate timers for this, but not all. Ideally
time the boiler to add heat to the domestic hot water after 4pm.
Second, even in winter some hot water is made by Solartwin, not all
by the boiler as you say. Third - the panel is well insulated and so
will still raise the temperature of water going into it since it
collects heat from the sun and not the air. Fourth - at 100% sun and
a water input temperature of 50C and air temperature of freezing our
mathematical model (based on extensive tests at Napier University)
suggests that the water will still leave the panel at least 10C
hotter than when it went in. Fifth - if they really want to put cold
water in under these circumstances they can connect a second
cylinder behind the first and draw water off it! This will also
allow for more summer hot storage and is a neat solution for people
with AGAs and Rayburns. "
BTW, unless variable speed pumping is in use it takes
more than a few watts to run the pump.
The tiny little Solartwin pump I have at the moment appears to be
about a 5W max unit,
The panel is limited to 4W output and the pump under-run. However,
the fact that this system uses low power pumping does not mean that
they all do. Even with variable speed pumping I suspect that 50-100W
is a fairly typical electricity consumption for a mains powered
system.
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.
A quick reality check on your assertion is to note what the
manufacturer of the system most mentioned has to say on this
http://www.solartwin.com/is_solartwin_suitable.htm
That you for confirming that what I said was correct.
I have left in what you said, "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".
In response I pointed to the most well known supplier of solar
pumped panels, where they explicitly talk about water hardness.
Therefore your statement that they make, "little or no mention", is
incorrect.
--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54