Hayward Universal H series 250k btu shows a minimum flow rate of 25gpm. My flow meter is right after the heater and unless I get the flow up to 35 to 40 gpm the heater shows a low flow warning. I read about adjusting the pressure switch whether the pool is above or below the water level. Mine is likely 2ft below. Anyone else come across this issue? Would be nice to get it to engage at a lower pump rpm if possible.