Produced energy calculation vs actual energy meter

[thorn storm]

Hi, I have a air to water heat pump and HA calculates the momentary power output from heat pumps inlet and outlet temps and from water volume flow. Energy dashboard then calculates the total produced energy.

These readings come from modbus and are updated every 10s.

Now have installed mid calibrated kamstrup multical 303 to also measure the heat output.

The readings from modbus are offset to really close to match the ones that kamstrup shows.

The HA calculated power and what kamstrup tells now match very close, say within 100 watts.

What is weird is the difference with the total heat output.

In a 24h period, kamstrup measured 17.5 kwh, and HA calculated 27,4 kwh.

What could be causing this?

I trust the kamstrup to be very accurate.

[craggy torrent]

You'll have to share more details about the calculation

How exactly do you calculate the 27.4 kWh

[lilac marten]

this seems like an quite unreliable assumption that creating the in-out difference would need a constant amount of electricity to be supplied

[thorn storm]

Formula is 4,1876 kJ/kg°C * flow rate*in/out temp difference divided by 60s

This is to get the instant water power output in sensor, and it matches with the kamstrup. 27.4 kwh comes from the total sensor. Whereas in same period mastrup measures total of 17.5kwh.

[craggy torrent]

How do you integrate?

Power to energy

[thorn storm]

Think it was a helper, rheimann or something like that. Also the power sensor is used in the energy dashboard to get hourly energy production. They both calculate the same total production.

[craggy torrent]

What does the graph of the power sensor look like?

How is the riemann sensor setup?

[thorn storm]

Its set to trapezoidal. Graph is pretty stable, no large spikes. Changed method to left now.