Vaillant EcoTec Plus 630 Pump Curve

[John Carroll]

Can someone explain or throw some light on the above, this boiler's hydraulic settings can be set to several modes, constant speed, dp constant pressure (between 100mbar & 400mbar) and dT Temperature Spread (between 10C & 20C). This boiler is having problems in running in either dP or dT modes so is running in constant speed mode until problems resolved.
The EcoTec 430 gives the actual HEX pressure loss so relatively easy to calculate the Residual Head with any known circ pump, I have done a few calcs based on using a 6M (Wilo) pump.
The EcoTec 630 does not give this very useful info, nor do they give the boiler's installed pump head, it does give a "Pump Curve" (see attached) which shows flow rates of 25.8LPM @ 100mbar head, 23.0LPM @ 200mbar and 19.0LPM @ 400mbar which makes no sense to me as the flowrate is apparently decreasing with increased pump head, hence the query. The boiler comes in default dP mode, set to 200mbar.
The D parameters showed (actual) flowrates of 11.65LPM @ 50% pump speed, 20.6LPM @ 80% and 25.47LPM @ 100%.
This boiler has a Vaillant LLH installed.

Residual Pump Head Extract Rev0.xlsx

Edited 12 hours ago by John Carroll