Bryant 140/E series Installation, Start-Up, Operating And Service And Maintenance Instructions page 38

Fig. 47 - - Gas Control Valve
Fig. 48 - - Orifice Hole
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 im-
portant with straight- -run ducts.
b. When thermometer readings stabilize, subtract return- -air
temperature from supply- -air temperature to determine air
temperature rise.
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 0.50- -In. W.C.
c. Adjust air temperature rise by adjusting blower speed. In-
crease blower speed to reduce temperature rise. Decrease
blower speed to increase temperature rise
A06666
* Continuous---blower speed---as shipped default
{ Not available on 1/5 HP motors.
BURNER
ORIFICE
A93059
38
d. d. Turn thermostat down below room temperature and re-
move blower access door.
e. 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.
f. Repeat steps a through e.
g. When correct input rate and temperature rise is achieved,
turn gas valve ON/OFF switch to OFF.
h. Remove manometer or similar device from gas valve.
i. Reinstall manifold pressure tap plug in gas valve.
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.
Table 11 – Speed Selection
COLOR SPEED
White Common
Black High
Yellow† Med --- High
Blue Med --- Low
Red Low*
CAUTION
!
FURNACE OVERHEATING HAZARD
Failure to follow this caution may result in reduced furnace
life.
Recheck temperature rise. It must be within limits specified
on the rating plate. Recommended operation is at the
mid- -point of rise range or slightly above.
6. Set thermostat heat anticipator.
a. Mechanical thermostat - - Set thermostat heat anticipator
to match the amp. draw of the electrical components in
the R- -W circuit. Accurate amp. draw readings can be ob-
tained at the wires normally connected to thermostat sub-
base terminals, R and W. The thermostat anticipator
should NOT be in the circuit while measuring current.
(1.) Remove thermostat from subbase or from wall.
(2.) Connect an amp. meter as shown in Fig. 49 across
the R and W subbase terminals or R and W wires at
wall.
(3.) Record amp. draw across terminals when furnace is
in heating and after blower starts.
(4.) Set heat anticipator on thermostat per thermostat in-
structions and install on subbase or wall.
b. Electronic thermostat: Set cycle rate for 4 cycles per hr.
7. Adjust blower off delay The blower off delay has 4 ad-
justable settings from 90 sec to 180 sec. The blower off
delay jumpers are located on the furnace control board.
(See Fig. 24.)
To change the blower off delay setting, move the jumper
from one set of pins on the control to the pins used for the
AS SHIPPED
BLW
COOL
SPARE
HEAT
FAN