EXAMPLE: Finding the Loop GPM Flow

Boiler output BTU/HR, (I1) = 16,800,000 BTU
Main loop return temp, (T2) = 130 F
Main loop supply temp, (T1) = 140 F
Boiler supply temp, (T4) = 210 F
Boiler return temp, (T3) = 140 F

Results:
Main loop flow, (F1) = I1 / (500 * (T1-T2))
Actual boiler flow, (F3) = F1 * (T1-T2)/(T4-T3)
Boiler flow less circulation flow, (F2) = I1 / (500 * (T4-T2))
Circulator flow, (F4) = F3-F2

EXAMPLE: Finding the Boiler Output Load

Main loop flow, (F1) = 3200 GPM
Main loop return temp, (T2) = 130 F
Main loop supply temp, (T1) = 140 F
Boiler supply temp, (T4) = 180 F
Boiler return temp, (T3) = 140 F

Results:
Boiler output BTU/HR, (I1) = F1 * 500 * (T1-T2)
Actual boiler flow, (F3) = F1 * (T1-T2) / (T4-T3)
Boiler flow less circulation flow, (F2) = I1 / (500 * (T4-T2))
Circulator flow, (F4) = F3-F2