Measure Gas Flow (Natural Gas Units); Burner Assembly; Rated Gas Inputs At Indicated Manifold Pressures - Bryant 588A Installation, Start-Up And Service Instructions Manual

UNIT 588A, 589A
018040, 024040, 030040
024060, 030060, 036060, 042060
030080, 036080, 042080,
048080, 060080
036100, 042100, 048100, 060100
036120, 042120, 048120, 060120
048140, 060140
* When a unit is converted to propane, different size orifices must be used. See separate natural-to-propane conversion kit
instructions.
†Based on altitudes from sea level to 2000 ft above sea level. For altitudes above 2000 ft: reduce input rating 4% for each
additional 1000 ft above 2000 ft. In Canada, from 2000 ft above sea level to 4500 ft above sea level, derate the unit 10%.
NOTE: Unit size 018 is 588A only.

Measure Gas Flow (Natural Gas Units)

Minor adjustment to the gas flow can be made by changing
the manifold pressure. The manifold pressure must be main-
tained between 3.4 and 3.6 in. wg. If larger adjustments are
required, change main burner orifices following the recom-
mendations of national and local codes.
NOTE: All other appliances that use the same meter must
be turned off when gas flow is measured at the meter.
Proceed as follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on manifold (see Fig. 24), then con-
nect manometer at this point. Turn on gas to unit.
3. Record number of seconds for gas meter test dial to make
one revolution.
4. Divide number of seconds in Step 3 into 3600 (number
of seconds in one hour).
5. Multiply result of Step 4 by the number of cu ft shown
for one revolution of test dial to obtain cu ft of gas flow
per hour.
6. Multiply result of Step 5 by Btu heating value of gas to
obtain total measured input in Btuh. Compare this value
with heating input shown in Table 5. (Consult the local
gas supplier if the heating value of gas is not known.)
EXAMPLE: Assume that the size of test dial is 1 cu ft, one
revolution takes 30 seconds, and the heating value of the gas
3
is 1050 Btu/ft . Proceed as follows:
1. 30 seconds to complete one revolution.
2. 3600 ÷ 30 = 120.
3
3. 120 x 1 = 120 ft of gas flow/hr.
4. 120 x 1050 = 126,000 Btuh input.
If the desired gas input is 120,000 Btuh, only a minor change
in the manifold pressure is required.
Observe manifold pressure and proceed as follows to ad-
just gas input:
1. Remove cover screw over regulator adjustment screw on
gas valve.
2. Turn regulator adjustment screw clockwise to increase
gas input, or turn regulator adjustment screw counter-
clockwise to decrease input. Manifold pressure must be
between 3.4 and 3.6 in. wg.
Table 5 — Rated Gas Inputs at Indicated Manifold Pressures
GAS SUPPLY PRESSURE
(in. wg)
NUMBER
OF
Natural
ORIFICES
Min Max
1 4.0 13.0
2 4.0 13.0
2 4.0 13.0
2 4.0 13.0
3 4.0 13.0
3 4.0 13.0
MANIFOLD
PRESSURE
(in. wg)
Propane
Min Max Natural Propane
4.0 13.0 3.5 3.1
4.0 13.0 3.5 3.3
4.0 13.0 3.5 3.4
4.0 13.0 3.5 3.7
4.0 13.0 3.5 3.5
4.0 13.0 3.5 3.4
MANIFOLD
Fig. 24 — Burner Assembly
WARNING: Unsafe operation of the unit may result
if manifold pressure is outside this range. Personal in-
jury or unit damage may result.
3. Replace cover screw cap on gas valve.
4. Turn off gas supply to unit. Remove manometer from
pressure tap and replace pipe plug on gas valve. Turn
on gas to unit and check for leaks.
—24—
NATURAL GAS PROPANE*
Orifice Heating Orifice
Drill Input Drill
Size (Btuh)† Size
32 40,000 41
40 56,000 47
32 80,000 42
30 95,000 40
32 120,000 42
31 136,000 40
PIPE PLUG
Heating
Input
(Btuh)†
40,000
54,000
80,000
95,000
115,000
133,000