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Heat Pump Performance Analysis Web App using Modbus Data

 
Air Source Heat Pumps (ASHPs)
Last Post by cathodeRay 4 months ago
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 redzer_irl
(@redzer_irl)
Trusted Member Member
Joined: 3 years ago
Posts: 39
Topic starter 12/12/2025 2:38 pm   [#2664]

I wanted to share a web app I created to help visualise and analyse my heat pump data. The app uses Python to ingest CSV files from Home Assistant History or Grafana panel exports and to generate visualisations and summary data from the raw CSV data. This was designed using data I obtain using a Modbus interface for my Samsung Gen 6 Heat Pump. This tool is not validated but it independently calculates values such as heat output and COP and these match the data I am generating in Home Assistant.

I found the web app very useful to analyse my heat pump data in a structured way in order to be able to generate actionable changes from the analysis and to be able to track changes in the heat pump operation after making changes to the heat pump settings. There is also the option to generate data in a structured JSON format to enable review of the data by a homeowner/person who manages the heat pump (or by AI systems if you choose, but always verify the outputs). This output consistently generates the same metrics which should allow the tracking of potential issues or to track system behaviour following system changes.

If anyone would like to try it (there is sample data provided in the app), the link is below:

https://heatpump-therm.streamlit.app/

therm_Beginners_Guide.pdf
image

 

Findings from initial use

A major issue I uncovered with my Samsung Gen 6 Heat Pump (with Joule Smart Pre-Plumbed cylinder 200L DHW/60L buffer), is that the Joule control circuitry allows the secondary pump and the heating zone pumps to operate during DHW heating cycles (when the 3 way valve is in the DHW position). This has a negative impact on the efficiency of the system as the heat pump is outputting higher flow temperatures during the DHW cycle and the heating circuits are now operating at the same time.

Discovering this enabled me to change my DHW and room thermostat schedules to avoid the zones calling for heat during the DHW operating windows and this has had a noticeable impact on the operating efficiency.

 

I would be interested to see if anyone wanted to run their own data through the app and see what results they got. As this is the first app I have created (with a lot of assistance from Codex, Gemini and Claude) and the fact that I am in no way a professional in the software or heating systems industries, this is very much to be treated as a beta tool for informational purposes only.

 

Grafana Panels

It took me a while to get the Grafana panels configured so I could export the data. The only way I could get this to work was using 2 separate panels, State and Numeric

Heat Pump Export Data - State

SELECT "value", "state", "entity_id"
FROM "state"
WHERE
$timeFilter
AND (
-- Pumps / circulation
"entity_id" = 'underfloor_pump' OR
"entity_id" = 'downstairs_radiator_pump' OR
"entity_id" = 'upstairs_radiator_pump' OR
"entity_id" = 'primary_pump' OR
"entity_id" = 'secondary_pump' OR

-- Defrost (binary)
"entity_id" = 'heat_pump_defrost_status' OR

-- 3-way valve / immersion mode (value versions)
"entity_id" = 'heat_pump_3way_valve_position_value' OR
"entity_id" = 'heat_pump_immersion_heater_mode_value' OR
"entity_id" = 'heat_pump_hot_water_mode_value' OR
"entity_id" = 'heat_pump_hot_water_status_value'

)

Heat Pump Export Data - Numeric

SELECT "value", "entity_id"
FROM /.*/
WHERE
$timeFilter
AND (
-- Heat pump electrical / thermal
"entity_id" = 'heat_pump_power_ch1' OR
"entity_id" = 'heat_pump_heat_output' OR
"entity_id" = 'heat_pump_indoor_power' OR
"entity_id" = 'heat_pump_compressor_frequency' OR

-- Hydraulics / temps
"entity_id" = 'heat_pump_flow_rate' OR
"entity_id" = 'heat_pump_flow_temperature' OR
"entity_id" = 'heat_pump_return_temperature' OR
--"entity_id" = 'heat_pump_flow_delta' OR
"entity_id" = 'heat_pump_hot_water_temperature' OR

-- Room temps
"entity_id" = 'living_room_temp_humidity_temperature' OR
"entity_id" = 'playroom_temp_humidity_sensor_temperature' OR
"entity_id" = 'main_bedroom_temperature' OR
"entity_id" = 'bedroom1_temp_humidity_sensor_temperature' OR
"entity_id" = 'bedroom2_room_temp_humidity_sensor_temperature' OR
"entity_id" = 'ecowitt_weather_indoor_temperature' OR
"entity_id" = 'heat_pump_temp_humidity_sensor_temperature' OR

-- Environment
"entity_id" = 'heat_pump_outdoor_temperature' OR
"entity_id" = 'ecowitt_weather_humidity' OR
"entity_id" = 'ecowitt_weather_solar_radiation' OR
"entity_id" = 'ecowitt_weather_wind_speed' OR
"entity_id" = 'openweathermap_wind_speed' OR
"entity_id" = 'openweathermap_humidity' OR
"entity_id" = 'openweathermap_temperature' OR
"entity_id" = 'openweathermap_uv_index'
)

 

Note: Post recreated due to mod removal of the original post (mea culpa - I didn't read the updated forum rules and had used ChatGPT to help me summarise the operation of the app)



   
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bontwoody
 bontwoody
(@bontwoody)
Noble Member Contributor
Joined: 4 years ago
Posts: 1009
12/12/2025 3:11 pm  

@redzer_irl

Hi. I would mind having a go with this but use OEM. Can you give detail of the csv file required and i will try to recreate it. Thanks


House-3 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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 redzer_irl
(@redzer_irl)
Trusted Member Member
Joined: 3 years ago
Posts: 39
Topic starter 12/12/2025 3:46 pm  

@bontwoody I have learned that CSV wrangling can get complicated!

There are some sample Grafana files in the app which I think would be the best basis for manual CSV editing - one file for state data (e.g. 1/0, on/off etc) and another for numeric data.

image

For numeric, the format is:

image

For state, the format is (the data can be in either the value or state column depending on what data you have):

image

I haven't tried to do what you are attempting so your results may definitely vary. If you want to send me on a sample file, I can have a look at the format and see if anything can be done to accommodate it if I have some time over Christmas.



   
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bontwoody
 bontwoody
(@bontwoody)
Noble Member Contributor
Joined: 4 years ago
Posts: 1009
12/12/2025 4:01 pm  

@redzer_irl ok. Thanks I will have a look when ive got some time. 😁


House-3 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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cathodeRay
 cathodeRay
(@cathoderay)
Famed Member Moderator
Joined: 4 years ago
Posts: 2878
12/12/2025 5:55 pm  

@redzer_irl — all my heat pump data is in csv files, meaning I am used to getting subsets of data from those files. I use something called q Text as Data which is a command line program that lets you run sql like queries on csv files, which can be a very quick and useful way of getting subsets of data. Depending on how your source data is organised (best in one big file as far as possible) and what you want to get out, then something like this will get all the data for one entity and put it in a new csv file:

q -H -d , "select Time, value, entity_id from my_data.csv where entity_id = 'ecowitt_weather_humidity'" > humidity.csv

It can also output the data to the clipboard (| clip), and you have most if not all of the standard sql options available to you including doing maths on the data (sums, counts, averages etc) and even join operations, though the code does get more complicated for that. 

 


Midea 14kW (for now...) ASHP heating both building and DHW


   
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