White Rodgers 50A66-743 Specifications, ELECTRICAL RATINGS @ 77F 25C, Operating Temperature Range

SPECIFICATIONS

ELECTRICAL RATINGS [@ 77°F (25°C)]:		OPERATING TEMPERATURE RANGE:
Input Voltage: 25 VAC 50/60 Hz		-40° to 175°F (-40° to 80°C)
Max. Input Current @ 25 VAC: 0.45 amp		HUMIDITY RANGE:
Relay Load Ratings:		5% to 93% relative humidity (non-condensing)
Valve Relay:	1.5 amp @ 25 VAC 50/60 Hz 0.6 pf	MOUNTING:
Ignitor Relay:	2.0 amp @ 120 VAC 50/60 Hz	Surface mount multipoise
	(resistive)	Timing Specs: (@ 60 Hz**)

Inducer Relay: 2.2 FLA–3.5 LRA @ 120 VAC		maximum
Circulator Relay: 14.5 FLA–25.0 LRA @ 120 VAC	Flame Establishing Time:	0.8 sec
Flame Current Requirements:	Flame Failure Response Time:	2.0 sec

Minimum current to insure flame detection: 0.25 µa DC*

Maximum current for non-detection: 0.1 µa DC*

Maximum allowable leakage resistance: 100 M ohms *Measured with a DC microammeter in the flame probe lead

**At 50 Hz, all timing specifications should be increased by 20%

Gases Approved:Natural, Manufactured, Mixed, Liquified Petroleum, and LP Gas Air Mixtures are all approved for use.

TIMING SPECIFICATIONS

(All times are in seconds, unless noted otherwise

Event	Definition	50A66-743
Pre-Purge	The period of time intended to allow for the dissipation of any unburned	15
	gas or residual products of combustion at the beginning of a furnace
	operating cycle prior to initiating ignition
Trial for Ignition	The period of time between initiation of gas flow and the action to	4
Period (TFI)	shut off the gas flow in the event of failure to establish proof of the
	supervised ignition source or the supervised main burner flame.
Ignition Activation	The period of time between energizing the main gas valve and	4
Period (IAP)	deactivation of the ignition means prior to the end of TFI
Retries	The additional attempts within the same thermostat cycle for ignition	4 times
	when the supervised main burner flame is not proven within the first
	trial for ignition period.
Valve Sequence	Valve sequence period equals 4 seconds trial for ignition period x	20
Period	(1 initial try + 2 retries) + 12 seconds.
Interpurge	The period of time intended to allow for the dissipation of any unburned	15
	gas or residual products of combustion between the failed trial for
	ignition and the retry period.
Post-Purge	The period of time intended to allow for the dissipation of any unburned	5
	gas or residual products of combustion at the end of a furnace burner
	operating cycle. Post-purge begins at the loss of flame sense.
Lockout Time	ANSI standard rated module timing.	250
Heat Delay-To-Fan-On	The period of time between proof of the supervised main burner flame	45
	and the activation of the blower motor at Heat speed.
Heat Delay-To-Fan-Off*	The period of time between the loss of a call for heat and the	60/90/120/180
	deactivation of the blower motor at Heat speed.
Cool Delay-To-Fan-On	The period of time after a thermostat demand for cool before energizing	2
	the circulator blower motor at Cool speed.
Cool Delay-To-Fan-Off*	The period of time between the loss of a call for cool and the	2/45
	deactivation of the blower motor at Cool speed.
Ignitor Warm-up	The length of time allowed for the igniter to heat up prior to the initiation	20
	of gas flow.
Auto Reset	After one (1) hour of internal or external lockout, the control will auto-	60 minutes
	matically reset itself and go into an auto restart purge for 60 seconds.
Humidifier		Yes
Electronic Air Cleaner		Yes

*This time will vary depending on option switch position. The control is factory set at 90 seconds HEAT delay-to-fan-off and 45 seconds COOL delay-to-fan-off. See OPERATION section for further information.

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