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H2 Ratings – what are they?
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H2 ratings are a move towards assisting customers to make more informed
decisions on their Heat Pump unit’s performance. As such, the “Voluntary H2”
rating scheme has been introduced by EECA. H2 rates Heat Pump heating
performance outputs at 2°C outdoor ambient condition. This is a more real
average condition for Southern Australia and some mid and Southern New
Zealand locations. |
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| Heating capacity decreases when temperatures decrease
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As the outdoor ambient temperature reduces below 7°C there is less available heat
for an outdoor unit to recover. The ability of an outdoor unit to recover heat in these
low ambient conditions varies greatly between brands. Larger out door coil surface area,
compressor size, defrost strategy all affect heat recovery capacities at low ambient
conditions.
Superior Heat Pumps will have a lineal capacity decrease as outdoor ambient conditions decrease.
Many brands that are primarily designed for cooling have steep performance curve degradation when
ambient temperatures reach 0°C or below. Mitsubishi Electric publishes low ambient performance
output and COP data in sizing and sales guides and in our Service Technical Manuals for your
reference. |
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Colder climates need to be sized to H2 ratings to ensure optimum performance
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Where ambient conditions are regularly lower than 7°C a design ambient condition should be
selected and the low ambient performance guide used for the final unit selection.
For example in Timaru where ambient day and night time temperatures often reach 0°C and below
the 2°C rating should be used as a minimum. For optimum comfort looking at rated output between 0°C
or –5°C will give the best results, ensuring that in low ambient conditions the Heat Pump will
deliver performance that will reach set point and satisfy the end users expectations.
If 5.6kW of heating capacity is required to heat a room, a Heat Pump that is rated at 5.6kW heating
will not deliver 5.6kW at 0°C outdoor ambient temperature! Output at 0°C is likely to be 4.76kW. A
6.8kW Heat Pump however is likely to still provide 5.78kW of heating capacity at 0°C, as such would
be the correct choice.
It is therefore extremely important that units are not undersized
in low ambient conditions
The other option is to upgrade to a HyperCore® Inverter High Performance Heat Pump that is
guaranteed to provide the same amount of heat at 7°C, 0°C, -7°C, in fact right down to -15°C.
CLICK HERE for HyperCore® Inverter High Performance Heat Pump. |
