Which is more efficient one 100 gallon water heater or two 50 gallon water heaters?

Answer 1

I like to install two tanks -- if one goes down you still have hot water -- when you connect two tanks -- i would run cold water to first tank into top of cold water inlet -- then come out of the hot and run it to the bottom of the next tank

where your drain valve is -- just remove and install a tee and put the drain valve back in -- then come out of the top where the hot water outlet is and

install a by-pass valve so if one tank leaks you can turn the bad tank off and still have hot water till you can install another tank -- i have done this many times this way -- works good if you have enough room for two 50 gal tanks