Navien NFB-175 Mode D'emploi page 23

Pump Sizing for Use with Glycol
The use of glycol results in a greater head loss due to its higher viscosity compared to water. Heat transfer is also reduced as the glycol
concentration increases. The corrected flow rate and head loss values below must be used when sizing the boiler pump in order to maintain
similar performance as using 100% water for the heating system. Refer to the chart below.
20°F ΔT @ 30% glycol
Model
Flow Rate (GPM)
NFB-175 17
NFB-200 20
20°F ΔT @ 50% glycol
Model
Flow Rate (GPM)
NFB-175 19
NFB-200 22
Minimum Flow Rates through the Boiler for Use with Glycol
Model
For Use With 30% glycol
NFB-175 7.5
NFB-200 8.6
Head (Ft) Flow Rate (GPM)
6.0
7.7
Head (Ft) Flow Rate (GPM)
8.5
11.1
Minimum Flow (GPM)
For Use With 50% glycol
8.3
9.5
25°F ΔT @ 30% glycol
Head (Ft)
14 4.0
16 5.0
25°F ΔT @ 50% glycol
Head (Ft)
15 5.6
17 7.0
35°F ΔT @ 30% glycol
Flow Rate (GPM) Head (Ft)
10 2.2
11 2.6
35°F ΔT @ 50% glycol
Flow Rate (GPM) Head (Ft)
11 2.9
12 3.8
Installing the System Piping 23