Would you like $1000 to $2500 in
your bank increasing every year, after paying off you solar
water heater.
The beauty of solar
water heating is that every time the power companies increase
the price of electricity you get richer with solar water heating.
Introduction
In 1978 we installed
our first solar water heater. Back then things were mostly
experimental with home owner and plumbers making their own
collectors. The industry mostly settled on flat plate collectors
which consisted of a sheet of copper with 20mm copper tubes
brazed on to that sheet.
The collector plate
was positioned in a box with a sheet of glass over the top.
Things have not
changed much. The manufacturers are still producing flat plate
collectors made mostly the same way. The differences are that
some areas suffer frosts and some manufacturers have decided
to make the collectors from steel instead of copper and fill
them with antifreeze/corrosion inhibitor, the heated water
is sent to the hot water storage tank using a heat exchanger
in the tank to transfer the heat.
Recently the chinese
have released a new form of collector known as Evacuated Tubes,
which look like large flourencent tubes coloured black.
Although they have
not been around long in New Zealand it appears they may take
over from flat plate as they appear more efficient and do
not suffer from rust, condensation, mould growth under the
glass or frost, as the flat plate collectors do, due to the
vacuum inside the tubes. The tubes do not contain water.
We are not aware
of any testing of performance done to date to establish efficiency
claims.
What to
buy?
If you go to all
the manufacturers web sites there is that much info you would
be more confused than before you started, as there are about
a four dozen in New Zealand each with several different models
made with different materials and components. What you need
is some one independent and experienced to sift through it
all and make a recommendation.
We are currently
recommending one flat plate and one evacuated tube set, although
will install any
brand of collector.
We are not agents for any brand and will judge the collectors
on several points, and they are-
1. Must have no
steel components other than stainless steel.
2. If not stainless
steel then aluminium, power coated aluminium or copper .
3. We will only
install copper or stainless steel tanks.
4. We test the collector
against our base model to determine performance claims. This
is a race test. We connect thecollector on an identical hot
water system and its a race from sun up to sun down. We simply
look at the temperature in the tank to see who wins. Our flat
plate has beaten some evacuated tubes. We will not release
the data to other plumbers.
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