Honeywell L4017 - Manual (Page 5)

SETTINGS
LIMIT SETTING
To set the cutout point for the high limit switch,
move the high limit indicator (Fig. 9) to the desired set
point. Follow setting instructions furnished by the
furnace manufacturer whenever possible. The limit dif­
ferential is fixed at 25 F [14 C]. The switch breaks
at the setting and remakes 25 F [14 C] below the
set point.
-IMPORTANT-
The high limit setting is provided with a stop
to limit the maximum temperature setting. Do not
force indicator above this point.
FAN SETTING (ADJUSTABLE
DIFFERENTIAL)
The fan differential is adjustable from 15 to 50 F
[8 to 28 C]. The fan switch makes at the set point and
breaks 15 to 50 F [8 to 28 C] below the fan-on
setting, depending on the position of the fan adjustment
dial. To change the setting, move the fan-on indicator
(Fig. 9) to the desired temperature. Set the fan dif­
ferential adjustment dial (Fig. 9) to the desired dif­
ferential. For constant fan operation (L4017B only),
set the MANUAL-AUTO switch in the manual position.
FIG. 9-L4017B WITH COVER REMOVED. L4017A
IS SIMILAR BUT DOES NOT INCLUDE
THE MANUAL FAN SWITCH.
FAN SETTING (FIXED DIFFERENTIAL)
Set the fan indicator to the desired fan-off tempera­
ture. The fan will come on 35 F [19 C] above that
setting.
CHECKOUT AND TROUBLESHOOTING
CHECKOUT
1. Follow the furnace manufacturer’s instructions
for placing the furnace in operation. If a manual re­
set Pilotstat control is used, make sure that it is
holding in.
2. Set the thermostat and limit control to call for
heat. The main burner should light.
3. To check the high limit control, disconnect the
fan motor and close all dampers. Set thermostat to
call for heat. Main burner should light. When plenum
temperature reaches limit control setting, main burner
should shut off. When checkout is complete, connect
fan motor and open all dampers.
4. Make sure that the fan operates when the furnace
temperature rises to the setting and shuts off when tem­
perature drops below set point and through the desired
differential. On fixed differential models, the fan should
operate when furnace temperature rises to setting plus
differential and shut off when temperature drops to
setting.
OVERHEATING FURNACE (LIMIT SWITCH
FREQUENTLY CUTS OUT)
1. Make sure fan is operating by jumpering across
the fan terminals. If fan does not operate, check the
wiring.
2. Make sure that fan setting is low enough so that
the hot air is circulated from the furnace before the
plenum temperature nears the high limit setting.
3. If limit switch continues to cut out, check for
obstruction to airflow through furnace. Inspect for
clogged air filters and improperly adjusted dampers.
HONEYWELL MINNEAPOLIS, MINN. 55408 INTERNATIONAL Sales Offices in all principal cities of the world. Manufacturing in
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PRINTED IN U.S.A.