79
P/N 240010943, Rev. C [09/07/2016]
399 MBH - PRIMARY LOOP EQUIVALENT LENGTH CALCULATION & PUMP SELECTION
For 399MBH Boiler
(This boiler must be piped with a primary loop)
These charts are valid for piping diagrams on pages 14 & 18
Instructions:
1.
Pipe diameter determines pump size. Smaller the diameter of pipe, larger the pump. 399 Mbh boiler can be piped in
1¼" pipe. Use charts 1-2 to determine pipe size and respective pump size.
2.
Fill in chart using the 1¼" section first. Then consult chart 3 for pump selection.
3.
Pump size may be decreased by decreasing equivalent length of pipe. Use larger diameter pipe as primary loop to
decrease equivalent length. Use charts 2 or 3.
Note: The Figure below are based on industry average. Consult valve/fitting manufaturer for exact equivalent length or for
fittings not shown below.
Chart 1
A
B
C
Pipe Diameter
Fitting
Enter Number of
Fittings
Multiply By
Equivalent Length
A x B
1¼"
(Any pipe/fitting
larger than 1¼",
count as 1¼")
90° Elbow
3.1
45° Elbow
1.7
Tee-branch
6.3
Tee-through
2.1
Swing check valve
10.4
Lift check valve
62.5
Enter Total 1¼" straight pipe length in feet
Add up numbers in column C
Total equivalent length of Primary
Pump Factor
