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PLUMBING CONNECTION Summer 2017
natural fit for them.”
In the early days of heat pumps being
introduced to the Australian market, it
was seen more as a niche product, but
it is becoming a mainstream option.
As a result, Stiebel Eltron wants to
educate the installers on correct
system specifications, installation and
commissioning, hence Oliver’s presence
in Australia.
“It is important that specifiers and
installers understand the size of the
heat pump that will be needed and that
the heat load required is calculated
correctly,’ says Oliver. “It is not like a
gas system where you can simply put in
a bigger gas unit. If it is wrong, and its
in-slab, it is an expensive problem to fix
and can cause a lot of reputation loss
for the installer, specifier and Stiebel
Eltron.”
As an example, Darren and Oliver have
taken an approximation of systems
installed thus far in the Australian
market to highlight what a ‘typical’
6-star rated home would require.
House Specifications:
Star rating:
6
Area (sqm):
250
Residents:
4
Water usage (l/person):
200
Energy per sqm:
15kW
PRODUCT SPECIFICATIONS:
∫ Hot water heat pump and HSM Trend
connection system
∫ 200 litre buffer tank
∫ Internet interface
∫ Installation footprint of heatpump:
0.88 m
2
, buffertank: 0.3 m
2
and HSM
Trend connection: 0.47 m
2
∫ Operating at an outside temperature
range above +2
o
C for an internal
temperature of around 20
o
C
OUTCOMES
∫ Cost of kit including hot water
system: ~$15,000
∫ Annual coefficient of performance:
4.7 (20% electricity and 80%
environmental energy)
∫ Annual energy consumption for
heating and hot water: 4500 kWh
∫ Estimated annual cost for heating
and hot water ($0.30/kWh): $1,350
per year
∫ A 4 kW PV Installation could cover
100% of this energy
∫ CO
2
emissions: 2900 kg/year
∫ Using PV and a smart grid heat pump,
CO
2
can be 0 kg/year
An analysis by Sustainability Victoria
(2013) estimated that a large house
(220m
2
built prior to 2005 and 2-star)
with a high standard gas hydronic,
zoned system would typically cost a
Melburnian $4610 per year to operate.
For a 6-star home of the same size it
is nearer to $1400, however it
does not
include costs for hot water. The CO
2
emissions with a gas-based system
would also be higher at around 4900kg/
year.
Oliver’s calculations provide an
interesting figure in the coefficient of
performance – namely environmental
energy.
In simple terms, air-sourced heat
pumps absorb energy from the
environment and transfer this energy
into the hydronic or domestic hot water
systems. Operating in a similar fashion
to a refrigeration system, the heat
is not rejected, but collected. Power
is therefore needed to operate the
compressor to move the refrigerant
around the system. Buffer tanks and
domestic hot water heat pumps have
the ability to store thermal energy,
acting as batteries when solar PV is
creating excess energy through the day.
Linking it to a renewable electrical
source such as PV, therefore, enables
the system to virtually require zero
energy supply from the grid.
A smart grid ready heat pump, Oliver
says, can be managed by an energy
management system. In this way, all
appliances, including the hot water and
hydronic heating can be staggered to
operate throughout the day at a time
when solar energy generation is at its
greatest, storing the energy for times of
low sun.
“We need to help plumbers make the
right choices with the equipment that
is needed to do a heat pump-based
hot water service and hydronic heating
system,” says Darren. “It is not as
simple as buying a bigger gas unit and
an extra couple of metres of pipe. With
Oliver here, we can now help plumbers
do it right the first time, to give the
homeowner the best possible solution
for their 6-star home.”
HEAT PUMP HYDRONIC HEATING SYSTEM INSTALLATION.
HEAT PUMPS AND HYDRONIC HEATING
The heat pump system comprises a pump assembly, circulating pump, expansion
vessel and controller
Pump
Assembly
Expansion
Vessel
Safety
Assembly
HMS Trend
Circulating
Pump
Digital
Controller