Nordyne M3RL Description of Components, Gas Flow Rate, Verifying Burner Operation

GAS FLOW RATE (CUBIC FEET PER HOUR)

TIME FOR	CUBIC FEET PER REVOLUTION OF			TIME FOR	CUBIC FEET PER REVOLUTION OF
ONE REVOLUTION		METER		ONE REVOLUTION		METER
(SECONDS)	1	5	10	(SECONDS)	1	5	10
24	150	750	1500	80	45	225	450
26	138	692	1385	82	44	220	439
28	129	643	1286	84	43	214	429
30	120	600	1200	86	42	209	419
32	113	563	1125	88	41	205	409
34	106	529	1059	90	40	200	400
36	100	500	1000	92	39	196	391
38	95	474	947	94	38	191	383
40	90	450	900	96	38	188	375
42	86	429	857	98	37	184	367
44	82	409	818	100	36	180	360
46	78	391	783	102	35	176	353
48	75	375	750	104	35	173	346
50	72	360	720	106	34	170	340
52	69	346	692	108	33	167	333
54	67	333	667	110	33	164	327
56	64	321	643	112	32	161	321
58	62	310	621	114	32	158	316
60	60	300	600	116	31	155	310
62	58	290	581	118	31	153	305
64	56	281	563	120	30	150	300

Table 11. Gas Flow Rate

after the gas valve is closed. This timing can be changed using the BLOWER OFF timing switch opposite the terminal block on the control board (See Figure 27).

Verifying Burner Operation

To verify operation of the burners, remove front door and ensure that the door switch is in the “on” position (see Figure 29). Set the thermostat above room temperature and observe the ignition se- quence. The flame can be observed through the small clear window on the burner box. The burner flame should carry over between all burners. The flames should be blue, without yellow tips. Flames should extend from each burner without lifting, curling, or floating. After verifying ignition, set the thermostat below room temperature and verify that the burner flame extinguishes completely. Replace the front door.

Verifying Operation of the Supply Air Limit Switch

To verify operation of the supply air limit switch, make sure that the blower door is in place and that there is power to the furnace. Completely block the return airflow to the furnace by install- ing a close-off plate in place of or upstream of the filter(s). Set the thermostat above room

temperature and verify that the Sequence of Operation is as described in these instructions. The supply air limit switch should function to turn off the gas valve within approximately five minutes. The circulating air and combustion blowers should continue to run when the supply air limit switch opens. Remove the close-off plate immediately after the supply air limit switch opens. If the furnace operates for more than five minutes with no return air, set the thermostat below room temperature, shut off the power to the furnace, and replace the supply air limit switch.

DESCRIPTION OF COMPONENTS

Figure 29 shows the location of each of the functional components described below. If any component of the furnace must be replaced, use only factory authorized replacement parts. Contact your distributor for the approved re- placement parts.

Flame Sensor – The flame sensor acts to prove that flame has carried over from the ignitor to the opposite end burner. If no flame is sensed, the furnace will be shut down automati- cally.

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