at the moment I try to build my own heat output counter from existing sensor measurements inside my database.
I know power input, deltaT between inlet and outlet. Only the circuit flow is a predicted constant as I have no flow sensor installed. With this values it should be possible to calculate the actual heat output and COP of my heat pump. So far so good, I can chart actual output and COP of my heat pump.
But I’m unable du cumulate current power (kW) to cumulated ones (kwH).
My latest state of error ist this query:
Select cumulative_sum("WärmeabgabeHK") as "WärmeabgabeHK" from ( Select last("WärmeabgabeHK") as "WärmeabgabeHK" from ( Select ((last("Kesseltemp") - last("TempPuffer2")) * 1150 * 0.00161)*1000 as "WärmeabgabeHK" ,last("status_WP") as status_WP ,last("status_Trinkwasser") as status_Trinkwasser ,last("PowerReal_P_Sum") as wp_Strom from calcBaseData where $timeFilter group by time(1h) fill(0)) where "status_WP" = 19 AND "wp_Strom" > 150 AND ("status_Trinkwasser" > 95 OR "status_Trinkwasser" <= 25 AND "WärmeabgabeHK" > 0) Group by time(1h) fill(null) )
Which results in an linux counter like increasing graph over the whole requested time range:
But as soon as I add a
cumulative_sum(last("WärmeabgabeHK"))... ...group by time(1d)
I receive a null output without any error. What I’m doing wrong?!