Set Temperature Rise - Bryant 373LAV Installation, Start-Up, And Operating Instructions Manual

TABLE 7—MODEL 373LAV ORIFICE SIZE AND MANIFOLD PRESSURE FOR CORRECT INPUT RATE*
(TABULATED DATA BASED ON ALTITUDE UP TO 2000 FT AND 23,000 BTUH PER BURNER)
GAS HEAT VALUE 0.56
(BTU/CU FT)
Orf Mnfld
No. Press.
40 3.2
860 41 3.5
— —
— —
875 41 3.3
42 3.7
— —
890 41 3.2
42 3.6
— —
905 — —
42 3.5
— —
920 — —
42 3.4
42 3.3
935 — —
— —
42 3.2
950 — —
— —
— —
965 43 3.7
— —
— —
980 43 3.6
— —
— —
995 43 3.5
— —
— —
1010 43 3.4
— —
— —
1025 43 3.3
44 3.8
— —
1035 43 3.2
44 3.7
— —
1055 — —
44 3.6
— —
1070 — —
44 3.5
— —
1085
44 3.4
— —
1100
44 3.3
*For size 060135 only, deduct 0.1-in. wc from manifold pressure shown in table due to 22,500 Btuh per burner input. If resultant manifold pressure falls below 3.2-in. wc,
change orifice size.

2. Set temperature rise.

Furnace must operate within range of temperature rise
specified on the unit rating plate. Determine the air tem-
perature rise as follows.
a. Place duct thermometers in return and supply ducts as
near furnace as possible. Be sure thermometers do not
"see" heat exchangers so that radiant heat does not affect
thermometer readings. This is particularly important
with straight-run ducts.
b. When thermometer readings stabilize, subtract return-air
temperature from supply-air temperature to determine
temperature rise.
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60
Orf Mnfld Orf Mnfld Orf
No. Press. No. Press. No.
40 3.3 40 3.4 40
41 3.6 41 3.7 41
39 — 39 3.2 39
40 3.2 40 3.3 40
41 3.5 41 3.6 41
— — — — 39
— — 40 3.2 40
41 3.4 41 3.5 41
42 3.7 — — —
— — — — 40
41 3.2 41 3.4 41
42 3.6 42 3.7 —
— — — — —
— — 41 3.2 41
42 3.5 42 3.6 42
42 3.4 42 3.5 42
— — — — —
— — — — 41
42 3.3 42 3.4 42
— — — — —
— — — — —
42 3.2 42 3.3 42
— — — — —
— — — — —
— — 42 3.2 42
43 3.7 — — —
— — — — —
— — — — 42
43 3.6 43 3.8 —
— — — — —
— — — — —
43 3.5 43 3.6 43
— — — — —
— — — — —
43 3.4 43 3.5 43
— — — — —
— — — — —
43 3.3 43 3.4 43
44 3.8 — — —
— — — — —
43 3.2 43 3.3 43
44 3.7 44 3.8 —
— — — — —
— — 43 3.3 43
44 3.6 44 3.7 44
— — 43 3.2 43
44 3.5 44 3.6 44
— — — — 43
44 3.4 44 3.5 44
—13—
0.62 0.64 0.66
Mnfld Orf Mnfld Orf Mnfld
Press. No. Press. No. Press.
3.5 40 3.7 40 3.8
3.8 38 3.2 38 3.3
3.3 39 3.4 39 3.5
3.4 40 3.5 40 3.6
3.7 41 3.8 38 3.2
3.2 39 3.3 39 3.4
3.3 40 3.4 40 3.5
3.6 41 3.7 41 3.8
— 39 3.2 39 3.3
3.2 40 3.3 40 3.4
3.5 41 3.6 41 3.7
— — — 39 3.2
— 40 3.2 40 3.3
3.4 41 3.5 41 3.6
3.7 42 3.8 —
3.6 42 3.7 42 3.8
— — — 40 3.2
3.2 41 3.4 41 3.5
3.5 42 3.6 42 3.7
— — — —
— 41 3.2 41 3.3
3.4 42 3.5 42
— — — —
— — — 41
3.3 42 3.4 42
— — — —
— — — —
3.2 42 3.3 42
— — — —
— — — —
— 42 3.2 42
3.6 — — —
— — — —
— — — 42
3.7 43 3.8 —
— — — —
— — — —
3.6 43 3.7 43
— — — —
— — — —
3.5 43 3.6 43
— — — —
— — — —
3.4 43 3.5 43
3.8 — — —
3.3 43 3.4 43
3.7 — — —
3.2 43 3.3 43
3.6 44 3.7 —
c. Adjust air temperature rise by adjusting blower speed.
Increase blower speed to reduce temperature rise. De-
crease blower speed to increase temperature rise.
WARNING: Disconnect the electrical power before
changing the speed tap. Failure to follow this warning
could result in personal injury.
d. To change blower motor speed selections for heating
mode remove blower motor lead from control board
HEAT terminal. (See Fig. 11.) Select desired blower
0.68 0.70
Orf Mnfld Orf Mnfld
No. Press. No. Press.
— — 37 3.2
38 3.4 38 3.5
39 3.6 39 3.8
40 3.8 — —
38 3.3 38 3.4
39 3.5 39 3.6
40 3.6 40 3.7
— — 38 3.2
39 3.4 39 3.5
40 3.5 40 3.6
41 3.8 — —
39 3.3 39 3.4
40 3.4 40 3.5
41 3.7 41 3.8
— 39 3.2 39 3.3
— — 39 3.2
40 3.3 40 3.4
41 3.6 41 3.7
42 3.8 — —
— 40 3.2 40 3.3
41 3.5 41 3.6
3.6 42 3.7 42 3.8
— — — 40 3.2
3.2 41 3.3 41 3.4
3.5 42 3.6 42 3.7
— — — — —
— 41 3.2 41 3.3
3.4 42 3.5 42 3.6
— — — — —
— — — 41 3.2
3.3 42 3.4 42 3.5
— — — — —
— — — — —
3.2 42 3.3 42 3.4
— — — — —
— — — — —
— 42 3.2 42 3.3
3.8 — — — —
— — — — —
— — — 42 3.2
3.7 43 3.8 — —
— — — — —
— — — — —
3.6 43 3.7 43 3.8
— — — — —
3.5 43 3.6 43 3.7
— — — — —
3.4 43 3.5 43 3.6
— — — — —
0.72
Orf Mnfld
No. Press.
37 3.2
38 3.6
— —
— —
38 3.4
39 3.7
40 3.8
38 3.3
39 3.6
40 3.7
38 3.2
39 3.5
40 3.6
— —
39 3.4
39 3.3
40 3.5
41 3.8
39 3.2
40 3.4
41 3.7
— —
40 3.3
41 3.5
42 3.8
44 3.2
41 3.4
42 3.7
— —
41 3.3
42 3.6
— —
41 3.2
42 3.5
— —
— —
42 3.4
— —
— —
42 3.3
— —
— —
42 3.2
— —
— —
43 3.8
— —
43 3.7
— —