Bryant 355MAV Furnace User Manual


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NOTE: DO NOT set low-heat manifold pressure less than 1.3-in. wc or more than 1.7-in. wc for natural gas. If manifold pressure is outside this
range, change main burner orifices.
CAUTION: DO NOT bottom out gas valve regulator adjusting screw. This can result in unregulated manifold pressure
and result in excess overfire and heat exchanger failures.
NOTE: If orifice hole appears damaged or it is suspected to have been redrilled, check orifice hole with a numbered drill bit of correct size. Never
redrill an orifice. A burr-free and squarely aligned orifice hole is essential for proper flame characteristics.
f. Move setup switch SW-2 to OFF position after completing low-heat adjustment.
g. Jumper R and W2 thermostat connections on control center. (See Fig. 31.) This keeps furnace locked in high-heat operation.
h. Turn high-heat adjusting screw (5/64 hex Allen wrench) counterclockwise (out) to decrease input rate or clockwise (in) to increase rate.
NOTE: DO NOT set high-heat manifold pressure less than 3.2-in. wc or more than 3.8-in. wc for natural gas. If manifold pressure is outside this
range, change main burner orifices.
i. When correct input is obtained, replace caps that conceal gas valve regulator adjustment screws. Main burner flame should be clear blue,
almost transparent. (See Fig. 58.)
Table 13—Model 355MAV Orifice Size and Manifold Pressure for Correct Input
(Tabulated Data Based on 20,000 Btuh High Heat/13,000 Btuh Low Heat per Burner, Derated 2 Percent for Each 1000 ft Above
Sea Level)
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64 0.66
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
U.S.A. and Canada
0
to
2000
850 43 3.7/1.5 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4 42 3.4/1.4
875 43 3.5/1.5 43 3.6/1.5 43 3.7/1.6 43 3.8/1.6 42 3.2/1.4
900 44 3.7/1.6 43 3.4/1.4 43 3.5/1.5 43 3.6/1.5 43 3.7/1.6
925 44 3.5/1.5 44 3.7/1.6 44 3.8/1.6 43 3.4/1.4 43 3.5/1.5
950 44 3.4/1.4 44 3.5/1.5 44 3.6/1.5 44 3.7/1.6 44 3.8/1.6
975 44 3.2/1.3 44 3.3/1.4 44 3.4/1.4 44 3.5/1.5 44 3.6/1.5
1000 45 3.7/1.6 45 3.8/1.6 44 3.2/1.4 44 3.4/1.4 44 3.5/1.5
1025 45 3.5/1.5 45 3.6/1.5 45 3.7/1.6 44 3.2/1.3 44 3.3/1.4
1050 45 3.3/1.4 45 3.4/1.5 45 3.6/1.5 45 3.7/1.6 45 3.8/1.6
1075 45 3.2/1.3 45 3.3/1.4 45 3.4/1.4 45 3.5/1.5 45 3.6/1.5
1100 47 3.6/1.5 47 3.7/1.6 45 3.2/1.4 45 3.4/1.4 45 3.5/1.5
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64 0.66
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
U.S.A. and Canada
Altitudes
2001
to
3000
or
Canada
Altitudes
2000
to
4500
775 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4 42 3.4/1.4 42 3.5/1.5
800 43 3.5/1.5 43 3.7/1.5 43 3.8/1.6 42 3.2/1.4 42 3.3/1.4
825 44 3.8/1.6 43 3.4/1.5 43 3.6/1.5 43 3.7/1.5 43 3.8/1.6
850 44 3.6/1.5 44 3.7/1.6 44 3.8/1.6 43 3.5/1.5 43 3.6/1.5
875 44 3.4/1.4 44 3.5/1.5 44 3.6/1.5 44 3.7/1.6 43 3.4/1.4
900 44 3.2/1.4 44 3.3/1.4 44 3.4/1.4 44 3.5/1.5 44 3.6/1.5
925 45 3.7/1.5 45 3.8/1.6 44 3.2/1.4 44 3.3/1.4 44 3.4/1.5
950 45 3.5/1.5 45 3.6/1.5 45 3.7/1.6 45 3.8/1.6 44 3.3/1.4
975 45 3.3/1.4 45 3.4/1.4 45 3.5/1.5 45 3.6/1.5 45 3.8/1.6
1000 47 3.7/1.6 45 3.2/1.4 45 3.4/1.4 45 3.5/1.5 45 3.6/1.5
1025 47 3.6/1.5 47 3.7/1.6 45 3.2/1.3 45 3.3/1.4 45 3.4/1.4
ALTITUDE
RANGE
(FT)
AVG GAS
HEAT VALUE
(BTU/CU FT)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64 0.66
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
Orifice
no.
Manifold
Pressure
U.S.A. Only
3001
to
4000
750 43 3.7/1.6 43 3.8/1.6 42 3.3/1.4 42 3.4/1.4 42 3.5/1.5
775 43 3.5/1.5 43 3.6/1.5 43 3.7/1.6 43 3.8/1.6 42 3.2/1.4
800 44 3.7/1.6 43 3.4/1.4 43 3.5/1.5 43 3.6/1.5 43 3.7/1.6
825 44 3.5/1.5 44 3.6/1.5 44 3.8/1.6 43 3.4/1.4 43 3.5/1.5
850 44 3.3/1.4 44 3.4/1.4 44 3.5/1.5 44 3.7/1.5 44 3.8/1.6
875 45 3.8/1.6 44 3.2/1.4 44 3.3/1.4 44 3.5/1.5 44 3.6/1.5
900 45 3.6/1.5 45 3.7/1.6 45 3.8/1.6 44 3.3/1.4 44 3.4/1.4
925 45 3.4/1.4 45 3.5/1.5 45 3.6/1.5 45 3.7/1.6 44 3.2/1.3
950 45 3.2/1.4 45 3.3/1.4 45 3.4/1.5 45 3.5/1.5 45 3.7/1.5
975 47 3.6/1.5 45 3.2/1.3 45 3.3/1.4 45 3.4/1.4 45 3.5/1.5
1000 47 3.5/1.5 47 3.6/1.5 45 3.7/1.6 45 3.2/1.4 45 3.3/1.4
* Orifice numbers 45 are factory installed.
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