Retiree needs help with Rinnai R-85 and water lines
My husband and I are retiring, and we have purchased a 1900 square foot home that has a Rinnai R-85 tankless heater powered by natural gas. We are rehabbing the bathrooms, because after removing the floor and wall tile in both bathrooms we discovered rotten floor joists. The crawl space of the house had sprayed foam insulation, so the rotten floor joists were not discovered until we gutted the bathrooms. We jacked up the walls and replaced the floor joists, and we have temporarily screwed down the subfloor, so we can remove it to work on the water and drain lines. The hall bath will have one lavatory sink with faucet, a small bath tub with tub filler, a fixed shower head, and a hand shower for bathing grandchildren, washing the dog, and rinsing the tub after cleaning. The master bathroom will have two lavatory sinks and two faucets, a shower only with a ceiling mounted 8 inch rain shower head and a hand shower on a slider bar. Should the supply water lines be 3/4 inch as advised in many of the threads? We will appreciate any advice, because we have no experience with a tankless water heater. I hope to hear from all of you!