kilowatts.ioMy heat pump
6 kW R32 Mitsubishi Ecodan (PUZ-WM60VAA, FTC6). Water-side and refrigerant data read from the controller over CN105, electricity from a Shelly meter, every 30 s.
Warnings
Suspect refrigerant behaviour detected automatically in the chart window: Fri 16 Oct, 09:32 – now
Checking…
The system
Live readings sit where their sensors are.
History
Fri 16 Oct, 09:32 – now
Download every variable for this window: CSV · JSON(30 s resolution up to ~3 days, coarser beyond; JSON includes each variable's description)
Power
The gap between the lines is free heat taken from the outdoor air
Water temperatures
Heating water leaving and returning, the cylinder, the house and outside
Refrigerant temperatures
Discharge (orange) should sit well above the water flow temperature. When the two meet, liquid refrigerant is reaching the compressor
Superheat & subcool
Superheat at 0 means the compressor is running wet: less heat for the same electricity
Expansion valves
How far open the valves feeding refrigerant to the outdoor coil are (480 = parked)
Compressor, fan & flow
How hard it is working
Every variable, explained
Live values, with what each one means.
Power & efficiency
What goes in (electricity) and what comes out (heat). Heat divided by electricity is the COP: 3 means three units of heat for every unit of electricity.
- Electricity in
- –W
- Heat out
- –W
- Electricity (total)
- –kWh
- Heat (total)
- –kWh
Electricity the whole heat pump is using right now, measured by a meter on its supply. About 20 W when idle.
Heat being delivered into the water right now, worked out from the water flow rate and how much warmer the water leaving is than the water coming back.
Running total of electricity used since monitoring began. The period figure above the charts is the change over the selected time range.
Running total of heat delivered since monitoring began.
Water side
The heat pump warms water, which is pumped round the radiators or through a coil in the hot water cylinder.
- Flow
- –°C
- Return
- –°C
- Flow - return
- –K
- Flow target
- –°C
- Flow rate
- –L/min
- Cylinder
- –°C
- Room
- –°C
- Outdoor
- –°C
Temperature of the water leaving the heat pump. Lower is more efficient: heat pumps work best making lukewarm water, not hot.
Temperature of the water coming back after giving up heat in the radiators or cylinder.
How much the water cools on its way round. Multiplied by the flow rate it gives the heat delivered. (K, kelvin, is just a temperature difference in °C.)
The flow temperature the heat pump is aiming for. Set automatically from the weather and how warm the house is.
Litres of water pumped through the heat pump each minute, from its built-in flow sensor. Zero when the pump is off.
Temperature of the hot water cylinder that feeds taps and showers. It is heated overnight on cheap electricity.
Temperature at the room thermostat.
Outdoor air temperature at the heat pump. The colder it is, the more heat the house needs and the harder the heat pump works.
Refrigerant circuit
Inside the outdoor unit a refrigerant (R32) boils in the outdoor coil, picking up heat from the air even when it is cold, then is compressed so it gets hot enough to heat the water.
- Discharge temperature
- –°C
- Discharge superheat
- –K
- Subcool
- –K
- Evaporating temperature
- –°C
- Two-phase pipe
- –°C
- Expansion valve A
- –pulses
- Expansion valve B
- –pulses
- Electronics temperature
- –°C
Temperature of the hot refrigerant gas leaving the compressor (sensor TH4). It should be well above the water temperature; if it drops to about the water temperature, liquid refrigerant is reaching the compressor.
How far the gas leaving the compressor is above the temperature at which it turns back to liquid. Healthy is roughly 10–30 K. 0 means 0 or below: the gas is wet, which wastes energy and is hard on the compressor.
How far the liquid refrigerant has cooled below its condensing temperature after handing its heat to the water. A few degrees is typical. Negative readings are odd and may be a sensor quirk.
Temperature of the refrigerant boiling in the outdoor coil (sensor TH3). It must be colder than the outdoor air for heat to flow in: typically 5–10 °C below it.
A second refrigerant temperature in the outdoor unit (sensor TH6), where the refrigerant is part liquid, part gas.
Opening of the main electronic expansion valve, which meters liquid refrigerant into the outdoor coil. More pulses means more open. It parks at 480 when the unit is off.
A second expansion valve. On this unit it is set when a run starts and then mostly stays put.
Temperature of the heatsink on the inverter electronics that drive the compressor (sensor TH8).
Compressor & control
How hard the machine is working and what it has been asked to do.
- Compressor speed
- –Hz
- Fan
- –rpm
- Pump speed
- –%
- Hot water mode
- off
- Defrost
- off
- Heating paused
- off
How fast the compressor is running. Higher speed means more heat and more electricity. 0 means off.
Speed of the outdoor fan that blows air across the coil.
Water pump speed as reported by the controller.
On when the heat pump is heating the hot water cylinder instead of the radiators.
On while the outdoor coil is being defrosted. In cold, damp weather ice builds up on it and has to be melted off every so often.
On when the home automation has told the heat pump to stop heating, for example because the house is warm enough.
Wear
Lifetime counters. Frequent short runs wear a compressor more than a few long ones.
- Compressor starts
- –
- Run hours
- –h
Lifetime number of times the compressor has started. The controller only reports it in steps of 100.
Lifetime hours the compressor has run. Run hours divided by starts gives the average run length.