Bryant CONDENSING GAS FURNACE 352MAV Installation, Start-Up, And Operating Instructions Manual Download

Page: 48 / 52

Set Temperature Rise

CAUTION:

UNIT DAMAGE HAZARD

Failure to follow this caution may result in overheating
the heat exchangers or condensing flue gases in heat
exchanger areas not designed for condensate.
Temperature rise must be within limits specified on unit
rating plate. Recommended operation is at midpoint of
rise range or slightly above.

Place SW-1 in ON position. Jumper R to W/W1 and W2 to check
high-gas-heat temperature rise. To check low-gas-heat temperature
rise, remove jumper to W2. Determine air temperature rise for both
high and low gas heat. Do not exceed temperature rise ranges
specified on unit rating plate for high and low gas heat.

This furnace must operate within the temperature rise ranges
specified on the furnace rating plate. Determine the air temperature
as follows:

a. Place duct thermometers in return and supply ducts as

close to 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.

If the temperature rise is outside this range, check the following:

a. Gas input for low- and high gas heat operation.

b. Derate for altitude if applicable.

c. Return and supply ducts for excessive restrictions caus-

ing static pressures greater than 0.50-in. wc.

d. Adjust temperature rise by adjusting blower speed.

Increase blower speed to reduce temperature rise. De-
crease blower speed to increase temperature rise.

For high-heat, the following connections can be made at HI
-HEAT on control:

a. Med-high (Yellow)

b. Med (Orange) -Available only on 5-speed motors. Fac-

tory setting for these motors.

c. Med-Low (Blue) - Do NOT use for HI GAS-HEAT on

80K & 120K Btuh input models. Factory setting for
4-speed motors.

CAUTION:

UNIT DAMAGE HAZARD

Failure to follow this caution may result in damage to the
heat exchangers due to over temperature or condensate
corrosion.
1. NEVER connect Low Speed (Red) wire to

″

-HEAT

″

2. Do NOT connect Medium Low Speed (Blue) wire to

″

HI-HEAT

″

on 80,000 Btuh and 120,000 Btuh input

model sizes.

For low-heat, the following connections can be made at LO
-HEAT on control:

a. Med (Orange) -Available only on 5-speed motors

b. Med-Low (Blue)

c. Low (RED) - Factory setting.

WARNING:

ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal
injury or death.
Disconnect 115-v electrical power before changing speed
tap.

To change blower motor speed selections for heating mode,
remove blower motor lead from control HI-HEAT terminal. (See
Fig. 32.) Select desired blower motor speed lead from one of the
other terminals and relocate it to HI-HEAT terminal. See Table 13
for lead color identification. Reconnect original lead on SPARE
terminal. Follow this same procedure for proper selection of
LO-HEAT and COOL speed selection.

Set Blower Off Delay

a. Remove Blower Access Door if installed.

b. Turn Dip switch 2 and 3 ON or OFF for desired blower

off delay. See Table 9A and B or Fig. 31 and 32.

Adjust Blower Off Delay (Heat Mode)

If desired, the main blower off time delay period may be
lengthened or shortened when operating in the heating mode to
provide greater comfort. See Table 9 for position of switches and
Fig. 31 or 32 for location of switches on control center.

TABLE 12—GAS RATE (CU FT/HR)

SECONDS

FOR 1

REVOLUTION

SIZE OF TEST DIAL

SECONDS

FOR 1

REVOLUTION

SIZE OF TEST DIAL

Cu Ft