24
MODELS WITH ELECTRONIC FAN TIMER CONTROL AND SNAP-DISC LIMIT CONTROL
ELECTRONIC FAN TIMER INTEGRATES CONTROL OF BURNER AND CIRCULATOR
FAN OPERATIONS. CONTROL IS CENTRAL WIRING POINT FOR MOST OF FURNACE
ELECTRICAL COMPONENTS.
•
United Technologies 1158-120 has an adjustable fan on time set by selecting
dipswitch combination displayed in below chart. Fan on delay can be set at 30, 60,
90 or 120 seconds. Provides a delay between burner ignition and blower start-up to
eliminate excessive flow of cold air when blower comes on.
•
United Technologies 1158-120 has an adjustable fan off time of 2, 3, 4 or 6 minutes
as displayed in below chart. Fan off delay time starts when burner motor is de-
energized at end of call for heat. Blower shutdown is delayed to remove any residual
heat from heat exchanger.
•
Electronic fan timer board works in conjunction with snap disc limit controls,
performing a safety function, and breaks power to oil burner primary control, shutting
off burner if furnace over-heats.
• Limit control is thermally operated and automatically resets. Limit control is factory
installed, pre-set and is not adjustable.
• If limit control opens with United Technologies 1158-120 electronic fan control
,
circulating fan will energize. When limit closes, fan off timer begins. At the end of fan
off time cycle burner is energized, initiating normal burner cycle.
United Technologies 1158-120
Dip Switch Position
Blower Delay Times
1
2
3
4
On Seconds
Off Minutes
Off
Off
30
On
Off
60
Off
On
90
On
On
120
Off
Off
2
On
Off
3
Off
On
4
On
On
6