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Bryant Induced-Combustion 4-Way Multipoise 310AAV User Manual

Page 34

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f. Set thermostat to call for heat.

g. Jumper R and W thermostat connections on furnace control

board to start furnace.

h. Remove regulator seal cap and turn regulator adjusting

screw counterclockwise (out) to decrease input rate of
clockwise (in) to increase input rate.

i. Install regulator seal cap.

j. Leave manometer or similar device connected and proceed

to Step 4.

NOTE:

DO NOT set manifold pressure less than 3.2-in wc or

more than 3.8-in. wc for natural gas at sea level. If manifold
pressure is outside this range, change main burner orifices or refer
to Table 12 or 13.

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.

4. Verify natural gas input rate by clocking meter.

NOTE:

Gas valve regulator adjustment cap must be in place for

proper input to be clocked.

a. Turn off all other gas appliances and pilots served by the

meter.

b. Run furnace for 3 minutes in heating operation.

c. Measure time (in sec) for gas meter to complete 1 revolu-

tion and note reading. The 2 or 5 cubic feet dial provides a
more accurate measurement of gas flow.

d. Refer to Table 10 for cubic ft of gas per hr.

e. Multiply gas rate (cu ft/hr) by heating value (Btu/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 tempera-
ture rise range specified on unit rating plate. Determine the
temperature rise as follows:

NOTE:

Blower access door must be installed when taking tem-

perature rise reading. Leaving blower access door off will result in
incorrect temperature measurements.

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 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 tempera-

ture 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. wc.
4.) Dirty filter.

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

c. Adjust air temperature rise by adjusting blower speed.

Increase blower speed to reduce temperature rise. Decrease
blower speed to increase temperature rise.

Table 8–Altitude Derate Multipler for U.S.A.

ALTITUDE

(FT)

PERCENT

OF DERATE

DERATE MULTIPLIER

FACTOR*

0–2000

0

1.00

2001–3000

8–12

0.90

3001–4000

12–16

0.86

4001–5000

16–20

0.82

5001–6000

20–24

0.78

6001–7000

24–28

0.74

7001–8000

28–32

0.70

8001–9000

32–36

0.66

9001–10,000

36–40

0.62

* Derate multiplier factors are based on midpoint altitude for altitude range.

Fig. 46—Gas Control Valve

A04166

REGULATOR
SEAL CAP

REGULATOR
ADJUSTMENT
SCREW

REGULATOR SPRING

GAS PRESSURE
REGULATOR
ADJUSTMENT

MANIFOLD
PRESSURE TAP

INLET
PRESSURE TAP

ON/OFF SWITCH

1/2˝ NPT INLET

1/2˝ NPT OUTLET

Fig. 47—Orifice Hole

A93059

BURNER

ORIFICE

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