I am writing on behalf of seven families that need to pick the right water heater for our 7 unit condominium complex located in Santa Monica CA. The current water heater is a 13 year old american standard 100gal 199BTUs and has minor spots of rust appearing around the tank. Water heater manufactures have calculaters on their sites but their recommendations are so inconsistant that it is difficult to validate the right solution. The complex has five 2 baths and two 1.5 baths, 3 internal stacked and one common area washing machine, and there is no water softener. One suppler I called said that the rule of thumb is 10000 BTUs per unit plus 20% and recommended a 100gal 100BTU but said the trade off in price is that it will only last half as long as the 199BTU tank. I saw the episode on anode rods and looked into changing the anode but as noted, some tanks like mine hide the anodes under a layer of insulation and a metal cap. Due to age and the cost of dismantleing the water heater, changing the anode was not recommended. Hot water supply has never been a problem with the BTUs of our current tank. Our concern is being penny wise and hot water foolish. We need a commercial tank with the right combination of gallons and BTUs, and with an accessabe anode rod to extend its life and mazimize the cost benifit. Can you help us stay in hot water?