Tankless water heater sizing

[Jmcc64]

Here's the scenario. My wife leases an office bldg (approx 4500 sf.) The water heater, a 40-ish gal lo boy is leaking from around and below the cold water inlet. Thing is, the WH is in the corner of an interior room with base cabinets on both sides and some cabs immediately above. The entire room will more or less have to be ripped out to replace the WH. Really the only time the hot water is used is for hand washing, doing the dishes in the kitchen sink after work and the washing machine. The wiring is double 30 amp breaker. The one quote to install new tank is $2000 which is way more than we want to put into someone else's 45 yr old bldg. I'm thinking tankless but the only ones I can find that can use that power setup are kinda small 6.5kw "point of use" units 1.5-ish GPM. Anybody have any experience with these and if so would it be sufficient for the uses described above? That particular room is centrally located in the bldg., if that helps

 

[Breplum]

With the low-ish amps available, the instant hot WH will typically come with a flow restricting aerator to make temperature as good as possible. If there is a faucet in place without a compatible flow restricting aerator. Just use the charts from Chronomite or Eemax, look at the temp rise given your average ground water temp. To see if you’d be happpy with the results. The units can last a good handful of years. Elements do burn out fairly routinely.