Bard Bayrd Furnace 403293A - Manual (Page 22)

A. Exact haat anticipator setting. SECTION 1 5 — SEQUENCE OF OPERATION.
Exactly setting heat anticipator helps avoid potential call­
backs. If you have any of the following factors, set heat
anticipator to match actual current draw in circuit.
• The system contains controls other than those
specified on wiring diagram;
• The system contains nonstandard (18 AWG) size
thermostat wire;
• The system has longer than a 30-foot distance
between thermostat and furnace.
Follow these steps to exactly set heat anticipator:
1. Use 2-foot piece of 24-guage thermostat wire,
stripped on both ends.
2. Use ammeter capable of reading exact amperage in
0-10 amp range. If it is adjustable, set on 0-10 scale.
3. Wind the 2-foot piece of 24-guage thermostat wire
ten times around one open arm of ammeter. Close
ammeter arms. This will act as a ten times multiplier.
4. Make sure 115-volt power to furnace is on. Connect
ends of wire on ammeter across terminals "R" and
"W" of thermostat sub-base. Follow Figure 22.
■Riermostat Sub-Base Terminals
Ten (10) Turns
>^24 Ga. Wire
Amprobe ^
5.
FIGURE 22
Read amp draw of furnace circuit on ammeter and
divide by 10. This gives you an exact heat anticipator
setting.
Example:
Meter reading - 9 amos
Divide by 10 turns - 10
Heat anticipator setting « .9 amps
6. Set room thermostat's heat anticipator to this amp
setting. Follow instructions provided with thermostat.
B. Approximate heat anticipator setting.
Find heat anticipator under room thermostat cover. Set
heat anticipator at 0.6 amps. Follow instructions provided
with thermostat.
See Figure 23 for furnace wiring diagram.
Thermostat calls for heat, energizing electronic ignition lock­
out module. Electronic ignition lockout module provides power
to gas control and igniter to light pilot. After proving pilot
flame, inducer relay (IDR) closes, energizing inducer motor.
Inducer motor starts and pressure switch closes, energizing
gas control and time delay relay (TDR). Time delay relay
energizes main blower within 20 to 30 seconds.
NOTE: If system locks out, set room thermostat below room
temperature for at least 10 seconds, then return to desired
setting. To purge gas lines, it may be necessary to operate
furnace through more than one lockout cycle at start-up.
After room thermostat is satisfied, gas control and inducer
relay are de-energized simultaneously. Inducer motor de-en­
ergizes and returns pressure switch to normally closed (N.C.)
position. Main blower remains energized through time delay
relay for up to 180 seconds.
SECTION 16 — INSTALLING DUCT WORK,
CAUTION: Install all duct work to meet current standards:
• ASHRAE/NFPA 90, Standard for Installation of
Warm Air Heating and Air Systems;
• State and local codes.
Failure to follow these standards could reduce air flow
or increase air leakage, resulting In reduced system per­
formance or furnace damage.
Properly size duct work based on heat loss and heat gain
calculations. Doing so assures:
• Good heating and cooling installations;
• Potentially fewer callbacks;
• Delivery of required circulating air.
For all furnaces, design duct systems for minimum and maxi­
mum external static pressures detailed in Figure 24. See
Section 25 on measuring duct work static pressure.
NOTE: When furnace is installed in an upflow position, air
delivery above 1800 CFM requires both sides of furnace be
used for return air, or a combination of one side and bottom
or bottom only.
Downflow installations use top return or top and side return.
Horizontal installations use end return or end and top return.
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