Commercial water heater output

If I have a 400,000 btu boiler heating water into a 370 gallon tank and I change the tank out to a 120 gallon tank, how much capacity do I loose? Assuming 95% eff boiler.

What's your usage rate and temperature? Incoming water temp?

output 130 deg incoming can be down to 40 boiler should put out 500 gph Just wondering what differance the tank will make.

ferd said:

If I have a 400,000 btu boiler heating water into a 370 gallon tank and I change the tank out to a 120 gallon tank, how much capacity do I loose? Assuming 95% eff boiler.

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Round numbers, the boiler heats produces 400 gallons per hour. FIRST hour delivery is the recovery rate ( 400 gallons per hour ) PLUS 70% ot tank. SO your first hour availablilty drops from 660 gallons to 485 gallons. After the first hour, it is all recovery, 400 gallons per hour.