Residential Heating and Cooling in Australia
on the net:
http://www.aussieairconditioning.com.au/services.html - a company that lists prices installed
of course, if you live in remote areas, you may need the more expensive LPG or install stand-alone power systems:
I have nothing to do with the heating / cooling industry, just trying to work out the best system for myself, if you find this useful then that's cool :)
I have attempted to make this information accurate at the time it was written (2008) but use this information at your own risk and consult with experts before deciding on a system.
this is a brief overview of some of the considerations for ducted heating and cooling systems for residential housing in southern latitudes of Australia.
it is likely that running costs are about to soar as general energy costs increase and house-holders will also have to contribute to greenhouse gas emission offsets either directly or indirectly.
to ensure the lowest running costs and most energy efficient use and thus minimising greenhouse gas emissions, it is imperative that we all adopt general principles of energy efficient housing which include:
appropriate orientation of house design:
living areas should face the north with reasonably large window area to allow the winter sun in while over-hanging eaves (measured for ceiling height and latitude but usually ~60cm) prevent summer sun from entering.
minimal walls and window areas to east & west where it is hard to stop the morning and afternoon sun entering in summer
minimal window areas to the south which leak heat in winter.
R2.5 ceiling and R1.0 wall insulation (for Melbourne)
curtains with pelmets
double glazed windows (laminated for wet areas and doors for safety)
minimise drafts around doors and close windows
high thermal mass:
concrete slab houses, etc help sustain temperature and help prevent rapid changes in temperature but in summer after a heat wave can take a while to cool down.
if a hot day is forecast, consider pre-cooling your house overnight
ability to zone areas so that the whole house need not be heated or cooled unnecessarily.
it does not make sense to have to heat & cool bedrooms all day long when no-one is in them.
but be aware that some systems have a minimum output and that zones need to be appropriately sized and matched to a system.
in summer, minimise heat from other devices such as TV's, computers, etc by turning them off when not needed.
running costs depend upon:
energy efficiency of your home
an energy efficient home in Victoria should reduce annual running costs by at least 30%
size of your home
annual running costs for heating in Victoria increase by ~15% for every 1 deg C increase in selected temperature
hours of operation
size of heating/cooling unit
NB. 1hp = 746W
will it heat your house or are you happy for it to only heat/cool half the house at a time (eg. living vs bedrooms).
see sizing calculators for air conditioning a room:
for a 50sq.m living area in Melbourne, facing north with ceiling insulation, a 5.6kW air conditioner is suggested
efficiency of heating/cooling unit
air conditioning systems are judged on their efficiency by:
heating: Coefficient of Performance (COP)
SRI = [ (tested COP x10) - 20 ] / 3
ie. 1 star for COP = 2.3 and add 1 star for each increase of COP of 0.3
cooling: Energy Efficiency Ratio (EER)
SRI = [ (tested EER x10) - 17 ] / 3
ie. 1 star for EER = 2.0 and add 1 star for each increase of EER of 0.3
see http://www.energyrating.gov.au/acstar.html for how these convert to Star ratings
ability to accurately control each zone in the house
if each room had its own thermostat and motor damper to control output, then in addition to more comfort control, running costs may be reduced by 25-40% as you can avoid over-heating/cooling areas and areas you don't need.
price you pay for your electricity / gas or whatever it runs on
NB. energy costs Melbourne, 2007:
0.91c/MJ natural gas;
17.4c/kWh peak electricity (7.6c/kWh off peak) - having risen by ~17% in Jan 2008 (I think these are correct).
some councils insist the outdoor unit must be at least 3m from a boundary to limit noise for neighbours - if neighbours complain it might cost you quite a bit to relocate it!
if you have a large house such as a double story and you want to air condition it, you will probably need to install 3 phase power.
ideally return air vents should be near the floor for the most effective heating system but as the air ducts are ~400mm diameter, this usually means sacrificing a wardrobe or similar to get the duct from ceiling to floor. As a compromise they can be ceiling mounted AWAY from vents (eg. in corridors).
return vent are about 1.2mx0.5m but a pair of smaller ones 450x550mm can be used instead
return vents have filters that need to be removed and vacuumed every 2-4wks
heating vents ideally should be at floor level but in concrete slabs you are forced to place them in ceilings, but at least the cooling works better there
heating vents need to be appropriately placed to provide even heating - usually near windows and avoid directly over beds.
are the ducts appropriately insulated and allergen free?
take particular care of how you set up zoning as this is decided before installation
how will the remote controller work with the zones and where will the thermostats be located
carefully read the user manuals BEFORE buying a system to ensure it will do what you want with zoning.
must one particular zone ALWAYS be set on and if so, will this make your system inefficient by forcing you to heat or cool an unused area of the house, particularly if this is large.
how will the system prevent users from inadvertently turning off all zones and obstructing the system thereby causing it to fail?
do you need a relief valve in the return ducts?
do you need to install extra thermostats or controllers?
will there be hidden costs such as modifications to power switch board?
whichever system you go for, whether electric or gas, if your electricity supply fails, your system will fail as they all need fans to drive the air. Fortunately, most systems will automatically re-start when supply returns.
in peak demand periods, if the State's electricity demands exceed supply then you risk being without cooling or heating.
Ducted Cooling Systems:
refrigerants used in air conditioners:
the older R22 refrigerant will be phased out by 2015 and none is slated to exist after 2030 in Australia due to the hydrochloroflourocarbons affecting the ozone layer.
the newer R410a refrigerant has zero ozone depleting potential but has some direct green house warming potential.
as R410a systems need higher specifications due to the need for higher pressure, it cannot be used in R22 systems.
advantages of using a system based on R410a over R22:
marginally more efficient
better for the environment
more readily serviceable when R22 is phased out
smaller unit size
R407C is another new refrigerant
cooling requires minimum 8" ducts (while heating requires minimum 6" ducts)
there are 4 main technologies:
the cheapest cooling system as it relies on blowing air through water to cool the air and uses systems which usually have large cube sited on top of the roof.
these systems do not work well at times of high humidity (ie. the more north you are in Australian coastal regions, the more likely you will face hot, humid weather which these systems will not cope with.
usually work well inland areas with low humidity
remote risk of Legionella - this is usually from commercial cooling towers not residential evaporative coolers.
some of these can be installed as add-ons to heating systems:
Vulcan / Conaire
multi head split refrigerant systems:
usually installed where you cannot run ducts due to concrete slabs combined with flat or cathedral roof.
can usually do 2 to 9 rooms with one outdoor unit
ducted reverse cycle air conditioners using inverter technology:
these also provide heat, fan & dehumidification
the inverter technology is said to be 30% more energy efficient than older reverse cycle technologies and avoids the high current start up as well as having quieter operation and more rapid heating/cooling with less over/under shoot of temperatures.
preferable to multi head split systems as fewer parts, fewer electronics & fewer potential refrigerant leaks.
this is the most energy efficient ducted refrigerant air conditioning system, particularly if you can zone your house to avoid unnecessary cooling of unused areas.
they will generally struggle to heat & cool the whole house simultaneously.
systems larger than 15.5kW will usually require 3 phase power.
a module sits in roof space while the condenser with its fans sits outdoors, preferably on the shady side of the house.
example of single phase power units:
Zone 10 system:
no need for a constant zone, and can control up to 10 zones but only 1 temperature sensor
for house with 10-12 outlets, indicative install price $A8,000-$A11,000
Gen III systems:
allows incredible control with users able to set a different temperature in up to 32 rooms via wireless communications network using touch screen controllers and wired controllers.
fantastic control for difficult situations such as double story houses, but complex & costly.
for house with 10-12 outlets, indicative install price $A12,000-$A16,000
a wired master controller which can be wired to:
up to 8 zone motors
a radio frequency module (RFM)
this can be wire connected to 3 slave RFM's to increase radio coverage
uses 433MHz frequency
a wired temperature sensor (WTS) - max. of 4
each can be wired to up to 8 room wired zone temperature sensors
a wired additional zones module (AZ) - max of 3
each can be wired to up to 8 zone motors
a wired pressure sensor module (PSDS)
monitors air pressure in the system and can modulate up to 3 zone motors to the dedicated "constant zones"
constant zones are zones designed to release excess air flow when too many dampers are closed
the number of dampers fully open in the system must be >= the number of constant zones, if less, then one of the constant zone dampers will open fully.
presumably also signals the main controller that filters may need cleaning
a wired Home Automation Module (CA3-HAM)
allows integration with 3rd party home systems, a GPRS modem, SMS texting.
optional air filters such as ionisers, UV lamps
a AAIRNET extension module
adds extra AAIRNET ports
up to 8 wireless remote controls can be used - a variety are available with various functionality
each zone can be named so you don't have to remember numbers
see here for tech pdfs: http://www.advantageair.com.au/go/residential/our-systems/tech-downloads
14.8kW single phase unit using R407C with input of 5.2kW
Fujitsu ART 54 LUAK:
cooling capacity 14.5kW which requires ~6kW input electricity at ~25amps to generate it
cooling output range 6.4kW-15.3kW and rated at 14.5kW with input 5.6kW at 23.5 amps
lowest input power 1.7kW ie. can drop down to ~25% output presumably
thus at 15c/kW, will cost $0.26-$0.90 per hour to run
ability to extract up to 4L moisture per hour
able to be used in fan only mode
3 star energy rating
interior fan 49db
exterior fans 54db (69dbA power)
up to 972L/min air circulation
can have up to 2 remote thermostat sensors, typically the main controller with thermostat is in the main living area and is set to be the thermostat during the day, while a remote controller with its thermostat is placed in a bedroom area and is set to operate at night.
interior temperature operating range 18-30deg C
exterior temperature operating range minus 15 deg C to 43deg C
optional fresh air intake system.
see users manual here (pdf)
these systems cost ~$A10,000 to install (2008)
Panasonic 14kW inverter
5yr warranty, made in Malaysia, Taiwan
Daikin FDYQ160M 15.5kW inverter
can control the unit from your mobile phone using Daikin's i-text technology
Australian & NZ
add-on ducted refrigerant air conditioning:
this uses refrigerant and a cooling coil in line with a ducted gas heating system
unfortunately there are currently no inverter models and the cooling output cannot be reduced as much as inverter models as the cooling coil tends to freeze and become inefficient.
may not be able to be used just as a fan as inverters can.
seems the minimum output is approx. 60% of total output.
some units only need single phase power, but these can only do about 100 sq.m at a time, larger units for the whole house require 3 phase power which can be expensive to connect to the house, if it is available.
these systems cost ~$A12,000 to install for both heating and add-on cooling (2008)
these systems usually allow up to 4 zones to be controlled on the remote controls but you may need to run a minimum of 2 zones at a time.
Bonaire B015 DC (Dual cycle) or RS:
cooling capacity 15.3kW which requires ?kW at ~26amps to generate it
outdoor compressor 58db
5yr warranty parts and labour
made in Australia & China
Brivis CDU15A-7D with IDU15A cooling coil:
cooling capacity 14.9kW which requires ~4.7kW input electricity at ~21.7amps to generate it
outdoor compressor 67db(A) power
outdoor temperature operating range 15-50degC
5yr warranty parts and labour
usually costs about $A6300 full installed as an add-on to compatible Brivis heating system (2008)
made in Australia
Ducted heating systems:
there are 2 main technologies:
ducted reverse cycle air conditioners using inverter technology:
also provides cooling, fan & dehumidification - see under cooling above
current models provide 4.5 star heating as they are just moving heat from the outside air (even though it is colder) to inside using refrigerant gas principles.
they are thus also called a heat pump.
Fujitsu ART 54 LUAK:
heating capacity 16kW which requires ~6kW input electricity at ~25amps to generate it
lowest input power 1.5kW ie. can drop down to 25% output presumably
thus at 15c/kW, will cost $0.23-$0.90 per hour to run
only needs single phase power
interior temperature operating range 16-30deg C
thus overnight, you can set it to HEAT mode (not AUTO) at 16degC and it will kick in automatically overnight when the temperature drops below ~16deg
exterior temperature operating range minus 15 deg C to 24deg C
ducted gas heating:
optionally can provide cooling via an add-on electrical air conditioning system but inefficient cooling as no inverter models available.
can choose efficiencies depending on price from 3 to 5 star energy rating which are based on energy output per megajoule of gas used.
a 4 star 14kW natural gas heater uses ~65MJ/hr which at 0.91c/MJ = $A 0.59/hr at full output
thus at current prices the 14kW gas heater will be a little cheaper than a 14kW inverter at $A 0.79/hr but the inverter should turn this around by having cheaper cooling than an add-on non-inverter cooling system.
a 4 star 20kW natural gas heater uses ~85MJ/hr which at 0.91c/MJ = $A 0.77/hr at full output
4 star rating; hot surface ignition (no pilot);
max. output 20kW;
airflow 860L/min (XA version required for use with add-on cooling)
usually costs about $A5200 fully installed (2008)
3yr warranty (10yrs on burner & heat exchanger) - check as this may change
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