Heat Pump Monitoring
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:
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 emonTx, 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 modbus electricity meter e.g SDM120
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:
The water flow and return temperature from the heat pump unit.
For air-source heat pumps: The outside air temperature.
For ground-source heat pumps: The source inlet and outlet temperatures.
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
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
Using our MBUS to USB reader that plugs into a EmonPi or EmonBase. Setup and emonhub interfacer configuration documentation is available here: MBUS Reader for Electric and Heat meters.
Reading from a Modbus SDM120 electricity meter using emonPi/emonBase
Please read our guide on selecting the right heat meter, available in our heat pump monitor github repository here: Github: Guide to selecting the right heat meter
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.
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Level 2 (no COP)
EmonPi: Electric & Temperature
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Level 2 (no COP)
EmonTx WiFi: Electric & Temperature
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Level 2 (no COP)
EmonTx + EmonBase: Electric & Temperature
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Level 3 (COP)
EmonPi with MBUS Reader for heat meter
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Level 3 (COP)
EmonPi with MBUS Reader
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Level 3 (COP)
RaspberryPi & MBUS based heat pump monitor
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