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Heat Pump Monitoring

HeatpumpMonitoring

The OpenEnergyMonitor system can be used to monitor the performance of heat pumps. The following covers a number of different configurations of the system from basic to more advanced monitoring.

Heat Pump Monitoring Data Comparison Website

We’ve setup heatpumpmonitor.org website to compare anonymous live data from real-world heat pump installations.


Level 1 (no COP): Electricity Consumption:

../_images/hpmon_config_emonpi_ct_only.png

At a basic level it is possible to use either the EmonTx or the EmonPi to monitor the electrical consumption of a heat pump by clipping a CT sensor around the supply to the unit. This provides detailed 10s resolution power consumption graphs as well as cumulative energy consumption in kWh on a daily/monthly/annual basis. It’s possible to use the power graphs to gain a basic insight into potential issues such as excessive cycling.

To install an emonTx4, emonTx3 or emonPi follow the general setup guides here, clip the CT sensor around either the insulated line or neutral cable for the heat pump rather than the whole house cable.

It is also possible to measure the electricity consumption with higher accuracy using a pulse output from an electricity meter or modbus output from an SDM120 DIN rail mounted meter.

../_images/hpmon_config_emonpi_ct_temps.png

Level 2 (no COP): System temperatures:

Since the performance of a heat pump is greatly affected by the working temperatures, it is very useful to monitor the following system temperatures:

  1. The water flow and return temperature from the heat pump unit.

  2. For air-source heat pumps: The outside air temperature.

  3. For ground-source heat pumps: The source inlet and outlet temperatures.

  4. The hot water cylinder temperature (top and bottom).

The EmonTx and EmonPi units both support temperature sensing using one-wire DS18B20 temperature sensors, see the following setup guide for examples of how to connect up temperature sensors:

The theoretical performance of a heat pump is given by the Carnot COP equation, see Github: A very simple heat pump model. For an air-source heatpump measuring the water flow temperature and the outside air temperature can be used to estimate the expected COP. Many heat pumps provide an indication of expected COP at different ambient air and water temperatures in their datasheets. The Emoncms heat pump app includes a tool to estimate COP using this equation.

Level 3 (COP): Flow rate & Heat metering:

Purchase Level 3 Heat Pump Monitoring Bundle

../_images/hpmon_config_emonpi_ct_mbus.png

The COP of a heat pump can be measured by measuring the heat output in addition to the electrical input. This can be done by either interfacing with a heat meter using MBUS (e.g: Sharky 775, Sontex superstatic 440, Kamstrup 403 or Qalcosonic E3) or a pulse counter, or a flow meter with an analog voltage output (Grundfos or Sika Vortex Flow Meter).

  • A heat meter with a pulse output can be connected to either the EmonTx or the EmonPi, see:
    + Add Pulse Counting

We recommend using the Modbus SDM120 electricity meter rather than the MBUS variant. We have found the Modbus version to be more reliable for this electricity meter.

My Heatpump dashboard

Emoncms includes an application specific heat pump dashboard available in the Apps module. The following video gives a good overview of what this dashboard can do, how to access daily electricity consumption and heat output data as well as detailed system temperature and power data.

There’s also a little feature shown briefly at the end that simulates the heat output and COP of the heat pump based on the Carnot COP equation.

It’s also worth checking out David Bowen (@MyForest) heat pump app, see community forum post: Heat Pump Experimentation App - Release News.

Configurations

As discussed above, there are a number of different hardware configurations that can be used for heat pump monitoring. The following gives a quick overview of the main options.

Level 2 (no COP)
EmonPi: Electric & Temperature
../_images/hpmon_config_emonpi_ct_temps.png
  • Easy installation on existing system.
  • Monitor electricity consumption and system temperatures.
  • Wifi or Ethernet connectivity.
  • EmonPi LCD makes setup easier.
  • Option to store and access data locally.
Level 2 (no COP)
EmonTx WiFi: Electric & Temperature
../_images/hpmon_config_emontx_wifi_ct_temps.png
  • Easy installation on existing system.
  • Monitor electricity consumption and system temperatures.
  • Wifi connectivity.
  • Requires cloud / remote server data storage.
  • Lowest cost of hardware.
Level 2 (no COP)
EmonTx + EmonBase: Electric & Temperature
../_images/hpmon_config_emontx_emonbase_ct_temps.png
  • Easy installation on existing system.
  • Monitor electricity consumption and system temperatures.
  • Wifi or Ethernet connectivity.
  • Option to store and access data locally on the emonBase.
  • 433 MHz radio link between EmonTx and EmonBase
Level 3 (COP)
EmonPi with MBUS Reader for heat meter
../_images/hpmon_config_emonpi_ct_mbus.png
  • Requires in-line installation of heat meter.
  • Monitor electricity consumption, system temperatures and heat output.
  • Accurate COP using heat and electricity measurements.
  • Wifi or Ethernet connectivity.
  • EmonPi LCD makes setup easier.
  • Option to store and access data locally or remote.
Level 3 (COP)
EmonPi with MBUS Reader
../_images/hpmon_config_emonpi_mbus.png
  • High accuracy electricity and heat monitoring.
  • Requires in-line installation of electric and heat meter.
  • Monitor electricity consumption, system temperatures and heat output.
  • Accurate COP using heat and electricity measurements.
  • Wifi or Ethernet connectivity.
  • EmonPi LCD makes setup easier.
  • Option to store and access data locally or remote.
  • Note: Modbus recommended for reading from SDM120 electric meters (Seperate Modbus reader required).
Level 3 (COP)
RaspberryPi & MBUS based heat pump monitor
../_images/hpmon_config_hpmonpi.png



  • High accuracy electricity and heat monitoring.
  • Requires in-line installation of electric and heat meter.
  • Monitor electricity consumption, system temperatures and heat output.
  • Accurate COP using heat and electricity measurements.
  • Option to store and access data locally or remote.
  • Slightly lower cost than EmonPi with external MBUS reader option.
  • Note: Modbus recommended for reading from SDM120 electric meters (Seperate Modbus reader required).
  • Purchase Level 3 Heat Pump Monitoring Bundle