Thousands of Btu per hour, using M in the Roman numeral sense of one thousand. A typical house boiler is 80 to 200 MBH, while a school might run several boilers of 1,000 to 4,000 MBH each. Ratings list input MBH, what the burner fires, and output MBH, what reaches the water, and the difference reflects efficiency. MMBtu/h, or million Btu per hour, is used for big plants.
Heat loss came in at 92 MBH, the old boiler is 210 input, no wonder it short cycles all winter.
Don't confuse MBH with MMBtu: one is thousands, the other millions, and a wrong M is a factor of a thousand.
Also heard as
- MBtuh
- MBtu/h
- kBtu/h
Related terms
Boiler horsepower
A boiler capacity unit equal to 33,475 Btu per hour, or evaporating 34.5 pounds of water per hour from and at 212 degrees F.
Short cycling
A burner starting and stopping far too often, with short run times that waste fuel and wear parts.
EDR
Equivalent direct radiation: the square-foot rating of heating radiators, used to size steam boilers.