CleaverBrooks 4WI, Operation, Service And Parts Manual

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750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual 6-17
6.16 — Gas Pressure and Flow Information
Btu/hr input = CFH (Cubic feet/hour)
Btu/cu. ft.
or
25,100,000 = 25,100 CFH (at 14.7 lb, atmospheric base 1,000 pressure)
then
25,100 = 21,271 CFH
1.18
This is the CFH (at line pressure) that must pass through the meter so that the equivalent full input requirement of
25,100 CFH (at base pressure) will be delivered.
6.16.4 — Checking Gas Flow
Your gas supplier can generally furnish a gas meter flow chart from which gas flow can be determined. After a
short observation period, the information aids in adjusting the regulator to increase or decrease flow as required to
obtain the rating.
Final adjustment of the gas fuel is carried out by means of the adjusting screws in the gas modulating cam, while
performing a combustion efficiency analysis. See Section 6.18 for details.
The information given in this section is for all practical purposes sufficient to set and adjust controls for gas input.
Your gas supplier can, if necessary, furnish exact correction factors that take into consideration Btu content, exact
base pressure, specific gravity, temperature, etc., of the gas used.
FIGURE 6-13.
Fuel Modulating Cam