A ABV is designed to work with a pump running in constant curve (fixed speed) mode so as the flow rate reduces the pump head rises and the ABV will start opening or open more depending on its setting.
The pump above if set to 250 mb constant pressure mode will maintain this pressure irrespective of the flow demand by inc/dec of the pump speed, so a ABV is not really suited to this pump mode but will give some form of control as the differential head across the ABV will vary a little with different flowrates and on where it is installe despite having a fixed pump head.
So if you want to try it, reduce the ABV setting until you feel the piping getting hot, if you are sure that the pump setting is 250mb then reduce the setting to 0.25 and then slowly further reduce it. If one uses the Honeywell DU144 ABV as a guide then with a pump head of 250mb and a ABV setting of 0.2 should give a by pass of ~ 350 kgs/hr or ~ 6 LPM, if the flow demand then increases the deltaP across the ABV should decrease a little and it should start closing in etc.
The pump above if set to 250 mb constant pressure mode will maintain this pressure irrespective of the flow demand by inc/dec of the pump speed, so a ABV is not really suited to this pump mode but will give some form of control as the differential head across the ABV will vary a little with different flowrates and on where it is installe despite having a fixed pump head.
So if you want to try it, reduce the ABV setting until you feel the piping getting hot, if you are sure that the pump setting is 250mb then reduce the setting to 0.25 and then slowly further reduce it. If one uses the Honeywell DU144 ABV as a guide then with a pump head of 250mb and a ABV setting of 0.2 should give a by pass of ~ 350 kgs/hr or ~ 6 LPM, if the flow demand then increases the deltaP across the ABV should decrease a little and it should start closing in etc.