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What you are looking at right now is a curve for an Air to Air Heat Pump.

Todb is the outdoor air temperature, which is the temperature of the air entering the outdoor coil (condenser in cooling mode, evaporator in heating mode). Tdb is the temperature of the air reaching the indoor coil (evaporator in cooling mode, condenser in heating mode).

What you are looking at right now is a curve for an Air to Air Heat Pump.

EIR_FT curve

  • Todb is the outdoor air temperature, which is the temperature of the air entering the outdoor coil (condenser in cooling mode, evaporator in heating mode). mode).
  • Tdb is the temperature of the air reaching the indoor coil (evaporator in cooling mode, condenser in heating mode).

What you are looking at right now is a curve for an Air to Air Heat Pump.

EIR_FT curve

  • Todb is the outdoor air temperature, which is the temperature of the air entering the outdoor coil (condenser in cooling mode, evaporator in heating mode).
  • Tdb is the temperature of the air reaching the indoor coil (evaporator in cooling mode, condenser in heating mode).

For an Air-To-Water heat pump, maybe you could look at using a biquadratic curve such as this one:

image description

Where:

  • Ta = Evaporator inlet air temperature (either dry-bulb or wet bulb)
  • Tw = Condenser inlet water temperature

Are you familiar with EnergyPlus? In the Example files, there is one called "HeatPumpWaterHeater.idf" that you should take a look at in particular (and a few others that have air cooled chillers)

What you are looking at right now is a curve for an Air to Air Heat Pump.

EIR_FT curve

  • Todb is the outdoor air temperature, which is the temperature of the air entering the outdoor coil (condenser in cooling mode, evaporator in heating mode).
  • Tdb is the dry-bulb temperature of the air reaching the indoor coil (evaporator in cooling mode, condenser in heating mode).

For an Air-To-Water heat pump, maybe you could look at using a biquadratic curve such as this one:

image description

Where:

  • Ta = Evaporator inlet air temperature (either dry-bulb or wet bulb)
  • Tw = Condenser inlet water temperature

Are you familiar with EnergyPlus? In the Example files, there is one called "HeatPumpWaterHeater.idf" that you should take a look at in particular (and a few others that have air cooled chillers)