For this reason the new controls
have certain timing functions if the
furnace does not light after the first
retry for ignition, called "self-
healing." If the first trial for ignition
fails. The control then runs the main
blower for a 180 seconds. This
attempts to cool and reset the HALC.
The gas valve can then open and
restart the furnace. All models use
this "self healing" feature.
Low Thermostat Anticipation
Because of the circuitry in the board,
the thermostat circuit amp draw
could be as low as 0.1
Oamps. This
could be below the minimum heat
anticipator setting of some
thermostats. However testing shows
0.10 continuous amps on a
thermostat with a 0.25 or 0.30 amp
minimum anticipator setting causes
very little temperature overshoot.
If necessary a resistor may be added
to increase the load to the "W"
circuit. See page 39.
Control Board Characteristics
The new controls have a newly
designed microprocessor. There are
different timing functions and
operations that previous IFC boards
did not have.
It has the "self healing" feature.
It makes four (4) tries for ignition
before locking out.
The blower on time is 20 seconds
after the gas valve opens and its
off delay is 90, 120, 160, or 180
seconds after burner shut down.
The UTEC -920/920A twinning
settings are with DIP switches in
the control center and by wiring the
two furnaces together. E2001
twinning settings are set by
removing a metal jumper in the
control center and wiring the two
furnaces together. See the section
on furnace twinning.
Its flame sensitivity could be as low
as 0.5 microamps making it much
less subject to nuisance
lock outs.
It should NOT BE AFFECTED BY
MOMENTARY POWER
OUTAGES. A brief power outage
or electrical interference ("noise" )
causes the unit to reset WITH
THE "OK" LIGHT OFF FOR
APPROXIMATELY ONE TO
THREE SECONDS. The furnace
then starts normally.
The "OK" light should never be
off for more than THREE
SECONDS at a time. If it is
REPLACE THE CONTROL.
Each control has a ONE HOUR
RETRY FOR IGNITION. If the
control goes into "soft" lock out, it
automatically retries for ignition
one hour later. This prevents total
loss of heat caused by a transient
condition.
There are new blower motor speed
terminals. One is marked "FAN" to
operate the blower constantly. The
other is marked "HEAT/COOL" to
operate both heating and cooling
on the same speed.
IMPORTANT: ALWAYS CONNECT
THE "Y" THERMOSTAT WIRE TO
THE "Y" CONTROL BOARD
TERMINAL. DO NOT SIMPLY
WIRE NUT THIS WIRE TO THE
WIRE GOING TO THE CONDENS-
ING UNIT. IF NOT CONNECTED
TO THE CONTROL BOARD THE
UNIT DOES NOT GO INTO THE
COOLING BLOWER SPEED.
After the cooling call ends
the blower continues for a
45-second off delay.
LED Flash Code
Beginning in 1998, the integrated
furnace controls will have a flash
code diagnostics feature. The "OK"
LED flashes to indicate a condition
that prevents the furnace from
operating. There is a two second
pause between each flash sequence.
FLASH CODE
1 blink Soft lockout (1 hour lockout)
2 blinks Open Pressure Switch
3 blinks Open Limit Switch
4 blinks Closed (shorted) Pressure
Switch
5 blinks Twinning Circuit Problem.
This feature became available with
the UTEC 1012-920A IFC.
77
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