CleaverBrooks CFC-500 Operation, Service And Parts Manual page 27

secondary loop arrangement.) Refer to table below for
minimum boiler circulation rates.
5) Minimum over-pressure at the boiler:
For outlet temperatures up to the maximum of 185 deg F (85 deg
C), a minimum operating pressure of 30 psig (2.1 bar) is required.
6) pH level should be maintained between 8.3 and 9.5
Minimum required boiler circulation rate (gpm) at maximum firing rate.
ClearFire
Model-Size
CFC-500
CFC-750
CFC-1000
CFC-1500
CFC-1800
CFC-2500
Notes/Limitations:
1. Maximum firing rate determined by ClearFire CFC - Glycol Firing Rate Limitation chart (below).
Maximum high fire blower speed should be set according to chart.
2. Glycol concentration limit of 25%-50%. Minimum required system operating pressure is 30
psig.
3. Maximum system operating temperature of 180 ˚F. Maximum ΔT of 40˚.
4. Circulation rates correlate with boiler output based on 92% nominal efficiency.
5. Standard altitude (<1000' ASL). Contact C-B for high altitude applications.
6. Pumps should be sized based on system design ΔT and minimum required flow rates.
7. At minimum firing rate, the minimum circulation rate should correspond to the boiler's turndown.
Part No. 750-263
Glycol Application Guidelines — ClearFire Model CFC
System ΔT (˚F)
ΔT = 10˚
88
131
175
263
316
438
ΔT = 20˚ ΔT = 30˚
44 29
66 44
88 58
131 88
158 105
219 146
Section 2 — Installation
ΔT = 40˚
22
33
44
66
79
110
2-13