Orifice Sizes, Combustion and Input Check

▲! CAUTION

Use a backup wrench on the gas valve when installing gas piping to prevent damage to the gas valve and manifold assembly.

TABLE 10

NATURAL GAS ONLY

TABLE OF CUBIC FEET PER HOUR OF GAS

FOR VARIOUS PIPE SIZES AND LENGTHS

PIPE			LENGTH OF PIPE
PIPE
SIZE	10	20	30	40	50	60	70
	10	20	30	40	50	60	70

1/2	132	92	73	63	56	50	46

3/4	278	190	152	130	115	105	96

1	520	350	285	245	215	195	180

1-1/4	1050	730	590	520	440	400	370

This table is based on pressure drop of 0.3 inch W.C. and 0.6 SP.GR. gas

TABLE 11

ORIFICE SIZES

INPUT	NUMBER	MAIN BURNER ORIFICE
RATING	OF	DRILL SIZE
BTUH	BURNERS	NAT. GAS	LP GAS

40,000	2	45	56
60,000	3	45	56
80,000	4	45	56
100,000	5	45	56
120,000	6	45	56

COMBUSTION AND INPUT CHECK

1.Make sure all gas appliances are off except the fur- nace.

2.Clock the gas meter with the furnace operating (de- termine the dial rating of the meter) for one revolu- tion.

3.Match the “Sec” column in the gas flow (in cfh) Table 13 with the time clocked.

4.Read the “Flow” column opposite the number of sec- onds clocked.

5.Use the following factors if necessary: For 1 Cu. Ft. Dial Gas Flow CFH =

Chart Flow Reading ÷2

For 1/2 Cu Ft. Dial Gas Flow CFH =

Chart Flow Reading ÷4

For 5 Cu. Ft. Dial Gas Flow CFH =

10X Chart Flow Reading ÷4

6.Multiply the final figure by the heating value of the gas obtained from the utility company and compare to the nameplate rating. This must not exceed the nameplate rating.

7.Changes can be made by adjusting the manifold pressure or changing orifices (orifice change may not always be required). To adjust the manifold pressure:

a. Turn off all electrical power to the system.

Installer’s Guide

b.Attach a manifold pressure gauge to the outlet pressure tap marked "OUT PRESS TAP" on White-Rodgers gas valve model 36F or boss marked "OUT P" on White-Rodgers gas valve model 36G. (See Figure 53 for White-Rodgers gas valve model 36F and Figure 54 for White-Rodgers gas valve model 36G.). For the gas valve model 36F, measurement requires removal of the plug and installation of a barbed fitting. Attach flexible tubing and a manometer to the barbed fitting. For the gas valve model 36G, do not remove the pressure tap test screw. Using a 3/32" hex wrench, loosen the pressure tap test screw one turn and install 5/16" flexible tubing and a ma- nometer directly onto the outlet pressure boss.

c. Turn on system power and energize valve. d.Remove the regulator adjustment screw cap on

the gas valve for manifold pressure adjustment. e.Turn the adjustment nut clockwise to increase the gas flow rate, and counterclockwise to de- crease the gas flow rate using a 3/32" hex wench.

f. The final manifold pressure setting shall be as specified in Table 12 with an input of no more than nameplate rating and no less than 93% of the nameplate rating, unless the unit is derated for high altitude.

g.Replace the regulator adjustment screw cap and tighten securely.

h.Turn off all electrical power to the system.

i. Remove the manometer and flexible tubing. Re- move the barbed fitting and replace the plug or tighten the pressure test screw.

j. Turn on electrical power to the system and ener- gize valve.

k.Using a leak detection solution or soap suds, check for leaks at plug or pressure boss screw.

18-CD22D1-8