52
FEATURES
<< Continued from page 51
However, there is often a disconnect between this design
and what is feasible when it comes to the building’s
reticulation. The designer must prove the design makes
use of an alternative heating source for water to meet
the 50% NBR, including but not limited to solar, propane
gas, heat pumps, or steam. The source selection criteria
involve various factors, such as location, climate, outlay
cost, and lifespan.
SOLAR
Ray Fernandez, business development manager at
Averge Technologies, sheds a little light on why solar
water heating (SWH) systems are a popular choice.
How it works
SWH systems offer a decentralised solution to the total
hot water supply need in warm, sunny climates. A gas
in-line booster or in-tank booster may be required to
offset the lack of solar radiation, especially in colder
climates with more rainfall. With a lifespan of 20 years
plus and the only moving part being water, operational
and maintenance costs are much lower than the
electric counterpart.
Cost
1.
2.
3.
Silver solar tanks
connected in parallel in
South Africa
Multiple unit installation in
Namibia.
Coloured solar tank.
Solar energy is free and renewable. Although SWH
systems may be pricey to purchase and install, they pay
for themselves over time in longevity and by not being
influenced by drastic electricity price increases. In fact,
these price increases will reduce the payback period. If
saving approximately 85% of your heating cost or 45%
1
2
February 2018 Volume 23 I Number 12
of your total electricity bill is not enough to persuade you
to go solar, perhaps the tax incentive will, or the fact that,
in the age of unplanned outages, solar energy can supply
an uninterrupted heat source.
Impact
If installed properly by a professional, SWH only takes
a short time to reheat, depending on the available solar
energy at the time and the type of boosting used, if any.
In-tank boosters take approximately an hour to generate
enough hot water to take a shower (at 45°C), while
in-line boosters provide hot water instantaneously. The
choice to go solar can also save the environment up to
four tons of carbon dioxide emissions per system per
year. This is equivalent to removing one small motor
vehicle from the road per year.
Maintenance
According to the Solahart fact file provided by
Fernandez, a SWH system operates on two natural
phenomena: black objects absorb heat and hot water
rises. Close-coupled SWHs are generally installed
outside of the roof and have no moving parts; therefore,
should anything happen, there is no collateral damage
to the house by way of ceiling repairs or wall painting.
The valves require routine maintenance, but not the
system.
Challenges
Orientation is essential. As far as possible, SWH
systems should be installed north facing, but more
efficient systems can be installed from east to west.
For indirect systems, the heat transfer fluid must be
pressure tested on commissioning of the system to
prolong lifespan and efficiency. The weight of the
systems should be taken into consideration. When
installing systems on roofs, a prop analysis must be
done under the guidance of a roof structural engineer.
Storage is also an important consideration, and a
proper sizing analysis must be done to make sure there
is enough storage capacity for the client/customer to
maximise their savings.
3
www.plumbingafrica.co.za