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FEATURE
on monthly electricity means the residential pay-back
period may be four to five years, the retail market
tends to find this too long, even though the savings
over a ten-year period can be R70 000. It also
requires annual maintenance which adds perhaps
another month a year to the pay-back.
Economies of scale
Closer to the domestic residential end of the market
with smaller heat pumps, is Stiebel Eltron. Niel
Bosman, Stiebel Eltron Southern Africa technical sales
representative, explains that the property market
is being driven more towards renewable energy by
the SANS XA requirements, though the problem is
whether it is a heat pump or thermal solar, it is still a
lot more expensive than a traditional geyser, “and if
a heat pump comes close to the price of a geyser I
would question its quality”.
Nico Jooste, Technical Sales at Stiebel Eltron.
H E A T P U M P S
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HEATING HEAT PUMPS
An energy efficient solution
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“Although there is a move in the market to heat
pumps, there is a lingering perception that they are
not delivering on promised savings. For a heat pump
to achieve its full COP it needs high consumption
rates. Its COP is not high when it only has to
moderately heat water.” Bosman explains that the
average COP is calculated by the energy required
to heat water from 25°C to 55°C, in a situation
where the water tank is completely drained and the
water fully reheated. When it is only partially used
and the water temperature drops, for example, to
only 45°C, the heat pump only has to increase the
temperature by 10°C, it doesn’t have the opportunity
to fully achieve the claimed COP. A heat pump is
consequently suited more to massive usage than
small draw offs, which means the heat pump is
constantly and inefficiently heating water by only
10°C. You will still get a saving compared to a geyser,
but not to the full potential. Perceptions of under-
performance are consequently a result of the wrong-
sized heat pump or water cylinder being specified; as
well as pipe distances between the heat pump and
the cylinder, which must be kept as short as possible.
All this influences the performance of a heat pump
and the efficiency you can get out of the system. This
distance is often a factor of the building or house
design, which the plumber can’t do anything about,”
says Bosman.
Suppliers are able to advise on the design, he says.
To obviate this mismatch Stiebel Eltron opted for the
integrated system of heat pump and cylinder, as a
single plug-and-play unit, as supply and return pipes
are not required such as for a split system.
“All the calculations for specifying the correct system
are done based on the end-user’s demands to
maximise on electrical savings and is ideally suited to
a standalone house with three or more occupants,”
says Nico Jooste, Technical Sales.
www.enerflow.co.za
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ST
ISO
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Proud Product of
Y AS
Contact us:
POTCHEFSTROOM HEAD OFFICE
+27 (0)18 297 0326/7 | info@enerflow.co.za
Branches in Port Elizabeth and wider Gauteng area
Installation of a heat pump has to be done by an
accredited technician – usually a qualified plumber
who is also accredited by the supplier: either by SA
Heat Pump Engineers locally, or in the case of Stiebel
Eltron, trained and accredited in Germany.
While large heat pumps are suited to, for example,
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March 2020 Volume 26 I Number 01