York D1NA018, D2NA060 Adjustment of Temperature Rise, Checking GAS Input, Secure Owners Approval

3.After maintenance of the pilot assembly, always measure the resistance across the ignitor. If the resistance is greater than 10 ohms, discard the ignitor and replace it with a new ignitor.

ADJUSTMENT OF TEMPERATURE RISE

° F Temp. Rise =	BTUH Output	(OR) CFM =	BTUH Output
	1.08 x CFM		1.08 x ° F Temp. Rise

The temperature rise (or temperature difference between the return air and the heated air from the furnace) must lie within the range shown on the rating plate and the data in Tables 2 and 3.

After the temperature rise has been determined, the CFM can be calculated as follows:

After about 20 minutes of operation, determine the furnace temperature rise. Take readings of both the return air and the heated air in the ducts about six feet from the furnace where they will not be affected by radiant heat. Increase the blower CFM to decrease the temperature rise; decrease the blower CFM to increase the rise.

DIRECT DRIVE BLOWER

All units have direct drive multi-speed blower motors. Refer to the unit wiring diagram and connect the blower motor for the desired CFM.

CHECKING GAS INPUT

NATURAL GAS

1.Turn off all other gas appliances connected to the gas meter.

2.With the furnace turned on, measure the time needed for one revolution of the hand on the smallest dial on the meter. Atypi- cal gas meter usually has a 1/2 or a 1 cubic foot test dial.

3.Using the number of seconds for each revolution and the size of the test dial increment, find the cubic feet of gas con- sumed per hour from Table 9.

If the actual input is not within 5% of the furnace rating with al- lowance being made for the permissible range of the regulator setting, replace the orifice spuds with spuds of the proper size.

NOTE: To find the BTU input, multiply the number of cubic feet of gas consumed per hour by the BTU content of the gas in your particular locality. (Contact your gas company for this information since it varies widely from city to city.)

SECURE OWNER'S APPROVAL

When the system is functioning properly, secure the owner's ap- proval. Show him the location of all disconnect switches and the thermostat. Teach him how to start and stop the unit and how to adjust temperature settings within the limitations of the system. Advise him that the flue exhaust hood surface and the immediate area will experience high temperatures during the heating cycle. All unauthorized personnel and debris must be kept away from this area.

		035-18265-001-A-0202
TABLE 9 - GAS RATE- CUBIC FEET PER HOUR
Seconds	Size of Test Dial
for One	1/2 cu. ft.		1 cu. ft.
Rev.
10	180		360
12	150		300
14	129		257
16	113		225
18	100		200
20	90		180
22	82		164
24	75		150
26	69		138
28	64		129
30	60		120
32	56		113
34	53		106
36	50		100
38	47		95
40	45		90
42	43		86
44	41		82
46	39		78
48	37		75
50	36		72
52	35		69
54	34		67
56	32		64
58	31		62
60	30		60

Example: By actual measurement, it takes 38 seconds for the hand on the 1-cubic foot dial to make a revolution with just a 100,000 BTUH furnace running. Using this information, locate 38 seconds in the first column of Table 9. Read across to the column headed “1 Cubic Foot,” where you will see that 95 cubic feet of gas per hour are consumed by the furnace at that rate. Multiply 95 x 1050 (the BTU rating of the gas obtained from the local gas company). The result is 99,750 BTUH, which is close to the100,000 BTUH rating of the furnace.

Unitary Products Group 11