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?

It’s a Marthon 27′ cabin cruiser with a Chevy/OMC 350 stern drive. I would like to convert it and was wondering what the cheapest and best way to do this is. I want to take it in salt water for extended periods and I don’t want to ruin the motor. I’ve been researching heat exchangers but it’s kind of confusing. Any advise appreciated, thanks.

I’m considering doing a solar water heater and getting a large storage tank to let me partially heat the house by doing a heat exchanger from the tank for our furnace. Is it worth trying?