Bard Bayrd Furnace 403293A - Manual (Page 32)

C. Changing orifices.
WARNINOz Before changing orifices, turn off
electrical power and gas. Failure to do so could
result In electrical shock or gas leak, resulting In
damage, injury or death.
1. Set room thermostat to its lowest or off setting.
2. Turn off electricity at electrical disconnect switch
next to furnace.
3. Turn off manual shut*off valve in gas supply line
just ahead of furnace.
4. Turn gas control knob clockwise -> to OFF posi­
tion.
5. Starting with burner farthest from gas control, re­
move burner screws and burners. Burners overlap.
Burner farthest from gas control is on top. See Fig­
ure 36.
6. Remove original gas orifices.
7. First, hand thread new orifices into manifold. Do
not cross-thread; then tighten to torque of 50 inch-
pounds.
FIGURE 36
8. Replace burners in reverse order from instructions
in Step 5,
9. Check burner carryover alignment. They should be
touching but not overlap adjacent burner. Replace
screws.
to. Turn gas control knob counter-clockwise <- to ON
position.
11. Open manual shut-off valve in gas supply line just
ahead of furnace.
12. Set room thermostat to its highest setting.
13. Turn on electricity at electrical disconnect switch
located next to furnace.
14. Check for gas leaks using commercial soap solu­
tion made for leak detection.
WARNING! Never use an open flame to check
for gas leaks. A gas leak could cause a fire or
explosion resulting in damage, Injury or death.
15. Check gas input following Section 21.
SECTION 24 — ADJUSTING BLOWER SPEED..
CAUTION: Heating speed tap should not be reduced
below initial factory setting. Reducing speed tap setting
may result in Inadequate air circulation, and could cause
excessive air temperature rise through furnace. This
could cause high-temperature limit switch to cycle burn­
ers on and off. This could reduce furnace efficiency and
shorten life of heat exchanger and blower motor.
1. All models have four blower speeds available for
use.
Motor speed designations are:
#1. High Speed (HI)
#2. Medium High Speed (MH)
#3. Medium Low Speed (ML)
#4. Low Speed (LOW)
2. Determine initial heating and cooling speeds in sys­
tem design stage. See Product Data sheet for air­
flow data. Depending on test results performed ir'
Sections 25 and 26, you may need to change blower
motor speed.
3. Turn off electricity at electrical disconnect switch
next to furnace.
WARNING: Failure to turn off electrical power
to furnace before changing blower motor speed
could cause electrical shock resulting In dam­
age, Injury or death.
4. Make blower speed changes at connector block lo­
cated at side of blower door. See Figure 37A.
FIGURE 37A
5. Never change the "C" common (WHT) wire.
6. To change cooling speed, black wire is moved to
desired speed. Cooling speed is controlled through
blower motor relay (BMR).
7. To change heating speed, brown wire is moved to
desired speed. Heating speed is controlled through
time delay relay (TDR). Heating speed should not
be reduced below initial factory setting.
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