Heat Loss Hub

Interactive Heat Pump Diagram

See the refrigeration circuit and the heating circuit working together — including the defrost cycle.

The cycle
Refrigerant
Cold refrigerantAbsorbing heatHot refrigerantHottest refrigerant
Heating water
Heating flowHeating return
Click any component
MONOBLOC AIR SOURCE HEAT PUMP2°C airThe complete refrigeration circuit is contained within the outdoor unit.YOUR HOMEcold liquid inwarmed vapour outOutdoor coilheat from air · frost 15%Fanpulls in airCompressorsqueezes gas → hotReversing valveHEATING positionExpansion valvedrops pressure → coldrefrig.waterhot gaswarm liquidcool inhot outHeat exchangerheat crosses, fluids never mixPumppushes water roundHeating FlowHeating Returnhot incooler outRadiatorswarms your roomswarming vapourhot gas
Live status
Heating
Outdoor air
2 °C
Flow temp
45.0 °C
Return temp
39.1 °C
Delta T
5.9 K
Heat output
5.3 kW
Estimated COP
2.52
Outdoor coil
Light frost
Suction / discharge
6.7 / 43.9 bar
Te / Tc
-5 / 50 °C
Conditions
2°C

Below about 7 °C with damp air, frost starts to form on the outdoor coil.

85%
45°C

Lower flow temperatures give a higher COP.

70%
Defrost cycle

In cold, damp weather moisture freezes onto the outdoor coil. The heat pump briefly runs backwards to melt it off.

  1. › Reversing valve switches, fan stops
  2. › Hot gas sent to the outdoor coil, ice melts, heating paused
  3. › Valve returns, heating output ramps back up