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c. The required flow rate can be calculated based
on the design temperature difference from the
return to the supply of the boiler. For a PI-T80
with a design temperature difference of 20°F the
calculation is as follows:
d. Table 3.3 shows the pressure drop (in feet of
water) for a flow rate which gives a 20°F
temperature difference for each boiler model.
e. The boiler pressure drop for various flow rates
can be determined by using Figure 3.2, the
Pinnacle Circulator Sizing Graph.
f. Table 3.4 gives the recommended circulators for
a boiler on a secondary loop with water as the
heating medium.
g. Special consideration must be given if anti-freeze is
to be used as a heating medium. Propylene glycol
has a higher viscosity than water therefore the
system pressure drop will be higher.
10. Indirect Water Heater: An indirect water heater
should be piped in a dedicated zone. It consists of a
water tank that is heated by boiler water passing
through an internal coil. Examples of indirect water
heating are shown in the System Piping subsection
of this Section.
WATER PIPING AND CONTROLS
The circulator sizing given is for primary/secondary
installations only. The system circulators must be
sized based on the flow and pressure drop
requirements of the system.
NOTICE
Output 64,000
= = 6.4 GPM
∆T x 500 20 x 500
Required Flow =
Table 3.3 – Flow Rate and Pressure Drop
Boiler
Model
Flow Rate
(GPM [LPM])
Pressure Drop
(Feet [meters])
PI-T50 4.0 (15.1) 4.5 (1.22)
PI-T80 6.4 (24.2) 5.0 (1.52)
PI-80 6.4 (24.2) 5.0 (1.52)
PI-140 11.2 (42.4) 8.0 (2.44)
PI-199 15.9 (60.2) 13.0 (4.02)
Table 3.4 – Recommended Circulators
Boiler
Model
TACO
Circulator
Grundfos Circulator
PI-T50 006 UPS 15-58FC SPD-1
PI-T80 007 UPS 15-58FC SPD-2
PI-80 007 UPS 15-58FC SPD-2
PI-140 0010 UPS 15-58FC SPD-3
PI-199 0011 UP 26-64F