The Hotline Newsletter

Let's Compare Numbers

How do you compare a Cambridge S-Series, high temperature Blow-Thru® unit to a low temperature draw-thru heater? Actually, it's like comparing apples to oranges because they are different technologies, designed for different applications. You can never match both the Blower CFM and Burner MBH ratings. In order to match MBH capacities, a low temp, draw-thru unit will always require a larger CFM rating than a high temp Blow-Thru® heater. See the following comparisons:

Specified Cambridge Heaters:

Model S2200
160°F Max Temp Rise/Discharge
Blower: 10,433 CFM
Burner Input: 2,200 MBH (1,202 Net MBH for conduction)

Draw-Thru Heater Options

Option #1 (Match just the Input MBH)
120°F Max Temp Rise/Discharge
Blower: 17,539 CFM
Input: 2,200 MBH (928 Net MBH)
Comparison: This unit requires 68% more CFM but provides 23% less Net MBH for conduction

Option #2 (Match the Net MBH)
Blower: 23,383 CFM
Input: 2,851 MBH (1202 Net MBH)
Comparison: This unit requires 42% more input MBH and 140% more CFM to provide the same Net MBH Capacity for conduction load. No wonder this unit is so big and costs much more to operate than the Cambridge model it is trying to replace!