rgamon, when you say a tankless is the single biggest user of gas, that
is untrue for many users. Ng tankless have true modulating gas valves.
My 117000 bosch runs from apx 30000 btu to 117000 btu, I have never
needed or used 117000 Btu even with 35f incomming water, I have never
set it to high and have hot showers. Now in summer even the lowest
setting is to warm for me. The bigger Takagi goes even lower to maybe
15000 btu, Tankless only use the energy needed to reach the temp
desired. Tankless have a much higher "Energy Factor" a true rating, than
tank.