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As to what it takes to grow the heat pump market, Vermeulen explains
that regulations require that 50% of water heating come from alternative
energy sources – typically heat pumps, solar energy or gas. He says
whichever is specified depends on the circumstances and design of the
building. “In some instances, solar will simply not work and a heat pump
will be specified. But there’s a place for each in the market. Solar heats
up the water during the day, but once it’s used, the system defaults to
electricity. With heat pumps you save two-thirds of your electricity, have
hot water all the time and you don’t have to provide for bulk storage, which
you do with solar.”
The pay-back time for a heat pump compared to alternatives is highly
variable, says Vermeulen, as it depends on hot water usage, ambient air
temperature and the COP of the actual device. It is commonly accepted
as being lower for industry and commercial buildings, Spires says 12-
18 months, while others say 18 to 24 or even 35 months for domestic
heat pumps.
Altmann says, “Of course the pay back time for heat pumps is dependent
on many influencing factors, like hot water consumption. To give you an
example, for a standard three-person household with showers, bath tub,
kitchen- and handwash sink, the amortisation will be with 4-5 years. The
savings that you can create in such a case with a heat pump, can be up
to R70 000 within a 10-year period.” To calculate the estimated return of
investment for your specific application, Stiebel Eltron offers a tool, that
you can download online, at: https://www.stiebel-eltron.co.za/toolbox/
tools/?excel.
Advancements in technology are being made all the time, but the pricing
has not reduced due to the impact of the exchange rate. In hard currency
terms, says Vermeulen, the price has come down to the exent that
prices have not increased in recent years even as the exchange rate has
considerably worsened. “For the same amount of money, today you get a lot
more advanced technology than what you would have had in 2010, when
Kwikot first started importing heat pumps. For instance, heat pumps that
heated water to 55°C now heat it to 75°C, the same as what you would
achieve with a resistance element – for a third of the energy.”
Major projects
Sun City in the North West includes four hotels including two five-star
hotels. Sun International wanted to reduce its impact on the national
grid and work towards Eskom’s aim of reducing demand by 10%, while
maintaining aesthetics and avoiding noise pollution.
Sun City is one of many other commercial operations who have opted to
install heat pumps either for environmental or economic reasons. In what
is one of the largest such projects in the country, seven HW80-3s were
installed at the Sun City Main Hotel, six HW20-3s at the Cascades Hotel,
two HW60-3s at the Sun City Cabanas and three HWW80-3s at the Palace
of the Lost City.
The hot water requirement was for 428 000ℓ/day at a temperature of
60°C, for an estimated energy saving of 1.28 GWh/year.
Three air-to-water heat pump exchanger setups and one water-to-water
heat pump exchanger setups were installed to heat 48% of the daily
demand. Solahart designed a solution that it says is unique to southern
Africa: a water-to-water heat pump system including the plant room and
piping for the Palace of the Lost City was installed. The water-to-water heat
exchanger helps to heat the 80 000ℓ/day of 60°C water that the Palace of
the Lost City requires. Three air-to-water heat exchanger solutions heat the
60 000ℓ/day, 40 000ℓ/day and 50 000ℓ/day of hot water for three hotels
respectively. The project resulted in a demand reduction of over 650kW.
Vaughan Boultwood, Rhem Australia Regional Sales and Marketing
Manager, explains, “A weir was built to dam the water from the river so
that we could use the thermal energy from the water and with a 5°C
differential maintain the heat in the pool to around 27°C without a pool
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August 2019 Volume 25 I Number 6