Bryant 355MAV GasRate Cu Ft/Hr, PROCEDURE 6-CHECKSAFETY CONTROLS, A. Check Primary Limit Control

Table 15—Gas Rate (Cu Ft/Hr)

SECONDS		SIZE OF TEST DIAL			SECONDS		SIZE OF TEST DIAL
FOR 1	1		2	5	FOR 1	1		2	5
REVOLUTION	Cu Ft		Cu Ft	Cu Ft	REVOLUTION	Cu Ft		Cu Ft	Cu Ft
10	360		720	1800	50	72		144	360
11	327		655	1636	51	71		141	355
12	300		600	1500	52	69		138	346
13	277		555	1385	53	68		136	340
14	257		514	1286	54	67		133	333
15	240		480	1200	55	65		131	327
16	225		450	1125	56	64		129	321
17	212		424	1059	57	63		126	316
18	200		400	1000	58	62		124	310
19	189		379	947	59	61		122	305
20	180		360	900	60	60		120	300
21	171		343	857	62	58		116	290
22	164		327	818	64	56		112	281
23	157		313	783	66	54		109	273
24	150		300	750	68	53		106	265
25	144		288	720	70	51		103	257
26	138		277	692	72	50		100	250
27	133		267	667	74	48		97	243
28	129		257	643	76	47		95	237
29	124		248	621	78	46		92	231
30	120		240	600	80	45		90	225
31	116		232	581	82	44		88	220
32	113		225	563	84	43		86	214
33	109		218	545	86	42		84	209
34	106		212	529	88	41		82	205
35	103		206	514	90	40		80	200
36	100		200	500	92	39		78	196
37	97		195	486	94	38		76	192
38	95		189	474	96	38		75	188
39	92		185	462	98	37		74	184
40	90		180	450	100	36		72	180
41	88		176	439	102	35		71	178
42	86		172	429	104	35		69	173
43	84		167	419	106	34		68	170
44	82		164	409	108	33		67	167
45	80		160	400	110	33		65	164
46	78		157	391	112	32		64	161
47	76		153	383	116	31		62	155
48	75		150	375	120	30		60	150
49	73		147	367

2.See thermostat manufacturer’s instructions for adjusting the heat anticipator and for varying heating cycle length. NOTE: When using an electronic thermostat, set cycle rate for 3 cycles per hr.

3.Return setup switch SW-2 to OFF position and replace thermostat on subbase.

PROCEDURE 6—CHECK SAFETY CONTROLS

A. Check Primary Limit Control

This control shuts off the combustion control system and energizes the air-circulating blower motor if furnace overheats.

1.The recommended method of checking this limit control is to gradually block off return air after furnace has been operating for a period of at least 5 minutes.

2.As soon as limit control has shut off burners, a 33 fault code will appear on control center.

3.The return-air opening should be unblocked to permit normal air circulation.

By using this method to check the limit control, it can be established that the limit is functioning properly and the furnace will operate safely if there is a restricted return-air supply or motor failure. If the limit control does not function during this test, the cause must be determined and corrected.

B. Check Pressure Switches

This control proves operation of the draft inducer. Check switch operation as follows:

1.Turn off 115-v power to furnace.

2.Remove control access door and disconnect inducer motor 12-pin wire harness at inducer motor.

—57—