We have two series connected 2.2 kw (3HP) centrifugal pumps used for domestic water supply from ground floor to over head tank at 25 m high. Delivery line has 100 mm dia. reduced to 40 mm dia. GI pipe If we change the 40 mm dia. GI pipe to 75 mm dia. GI or PVC pipe, will there be any saving on pumping time?

I would like how is the pump’s suction head related to its operational head? or discharge head? or on its performance…

i’m doing this experiment on heat exchanger. I’m supposed to discuss the effect of changing the flow rate on the overall heat transfer coefficient as well as the effect on the temperature and efficiency. I need some help so anything would be great.