58PHA
c.Measure time (in sec) for gas meter to complete 1 revolution and note reading. The 2 or 5 cubic feet dial provides a more accurate measurement of gas flow.
d.Refer to Table 12 for cubic ft. of gas per hr.
e.Multiply gas rate (cu ft./hr) by heating value (Btuh/cu ft.) to obtain input.
If clocked rate does not match required input from Step 1, increase manifold pressure to increase input or decrease manifold pressure to decrease input. Repeat steps b through e until correct input is achieved. Reinstall regulator seal cap on gas valve.
5.Set temperature rise. The furnace must operate within the temperature rise ranges specified on the furnace rating plate. Do not exceed temperature rise range specified on unit rating plate. Determine the temperature rise as follows:
NOTE: Blower access door must be installed when taking temperature rise reading. Leaving blower access door off will result in incorrect temperature measurements.
!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Disconnect
a.Place thermometers in return and supply ducts as close to furnace as possible. Be sure thermometers do not see radiant heat from heat exchangers. Radiant heat affects temperature rise readings. This practice is particularly important with
b.When thermometer readings stabilize, subtract
NOTE: Blower access door must be installed for proper temperature rise measurement.
NOTE: If the temperature rise is outside this range, first check: (1.) Gas input for heating operation.
(2.) Derate for altitude if applicable.
(3.) Return and supply ducts for excessive restrictions causing static pressures greater than
(4.) Dirty filter.
c.Reinstall blower access door if removed.
d.Turn gas valve ON/OFF switch to ON.
e.Adjust air temperature rise by adjusting blower speed. Increase blower speed to reduce temperature rise. Decrease blower speed to increase temperature rise
f.Turn thermostat down below room temperature and remove blower access door.
g.To change motor speed selection for heating, remove blower motor lead from control HEAT terminal (See Fig. 24.) Select desired blower motor speed lead from one of the other terminals and relocate it to the HEAT terminal (See Table 11 for lead color identification). Reconnect original lead to SPARE terminal.
h.Repeat steps a through e.
i.When correct input rate and temperature rise is achieved, turn gas valve ON/OFF switch to OFF.
j.Remove manometer or similar device from gas valve.
k.Reinstall manifold pressure tap plug in gas valve.
A06666
Fig. 52 - Gas Control Valve
BURNER 
ORIFICE
A93059
Fig. 53 - Orifice Hole
!WARNING
FIRE HAZARD
Failure to follow this warning could result in personal injury, death, and/or property damage.
Reinstall manifold pressure tap plug in gas valve to prevent gas leak.
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