Install Instructions

Table Of Contents

9. Circulator: The boiler circulator is to be sized to

overcome the pressure drop of the system while

providing the flow required by the boiler.

a. If the boiler is piped in a secondary loop of a

primary/secondary heating system, the circulator

will need only to overcome the resistance of the

boiler and any fittings in that loop.

b. The circulator should be sized based on gross

output of the boiler. Table 4.3 shows the Boiler

Output as reported to the Hydronics Institute

Section of AHRI.

c. The required flow is calculated based on the design

temperature difference from the return to the supply

of the boiler. For a PF-110 with a design temperature

difference of 20°F the calculation is as follows.

Output 101,000

Required Flow =

________

_________

= 10.1 GPM

T x 500 20 x 500

d. The boiler pressure drop for various flow rates can

be determined using Figure 4.4, the P

UREFIRE

Boiler Circulator Sizing Graph.

WATER PIPING AND CONTROLS

PUREFIRE

Model

Boiler Input

Btu/hr (kW)

Gross Output

Btu/hr (kW)

PF-50 50,000 (14.7) 46,000 (13.5)

PF-80 80,000 (23.4) 74,000 (21.7)

PF-110 110,000 (34.2) 102,000 (29.9)

PF-140 140,000 (41.0) 131,000 (38.4)

PF-210 210,000 (61.5) 193,000 (56.6)

PF-399 399,000 (116.9) 373,000 (109.3)

Table 4.3: Boiler Inputs and Outputs

Figure 4.4: PUREFIRE

Circulator Sizing Graph (General Pump – Primary/Secondary)

Figure 4.2: Relief Valve Installation – PF-50, PF-80,

PF-110 & PF-140

Figure 4.3: Relief Valve Installation – PF-210 & PF-399