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“B” Fixed indicator
(cut-in point)
“C” Differential adjusting
screw
“D” Movable indicator
(cut-out point)
“A” Adjusting
slot
“E” Stop screw
“F” Stop tab
BLUE
RED
WHITE
Common
Open on rise
of temperature
Close on rise
of temperature
All wiring should be done according to local and
national electrical codes.
If the boiler or burner manufacturer recommends a wiring
diagram, then follow such recommendations. If none are
offered, the instruction sheet for the primary control (gas
valve or oil burner control) may offer some suggested
circuits.
This control has a single-pole, double-throw snap action
switch. The top left-hand terminal (red) is the common
terminal. The top right-hand terminal (blue) has open-on-
rise switch action. The bottom center terminal (white) has
close-on-rise switch action.
Limit Control: When used as either a high limit control or
a low limit control, use the open-on-rise terminals (red and
blue).
Circulator Control: When used as a circulator control,
use the close-on-rise terminals (red and white).
Combination Low Limit and Circulator Control: For
this application, all three terminals are used.
The following wiring diagram shows a typical circuit for an
oil-fired system with domestic hot water without storage
tank.
NOTE
The low limit side of the low limit/circulator control main-
tains domestic hot water temperature all year around.
When the room thermostat calls for heat, the burner and
circulator operate. If boiler water temperature drops too
low, the circulator will stop until the temperature rises in
boiler.
SETTING THE CONTROL
CONTROLS WITH ADJUSTABLE STOPS
1. Loosen stop screw (E) with enclosed wrench.
2. Set dial to original equipment manufacturer's specifi-
cation.
3. Without moving the dial, move stop tab (F) against
indicator.
4. Re-tighten stop screw (E).
Setting stop higher than control being replaced
could cause personal injury and/or property dam-
age.
1. Use a screwdriver in the adjusting slot (A) on the front
of the control to turn the dial so the fixed indicator (B)
points to the lowest temperature of the cycle.
2. Turn the differential adjusting screw (C) until the
movable indicator (D) points to the highest tempera-
ture of the cycle.
The movable indicator points to the temperature at which
the contacts open on high limit and low limit applica-
tions. On circulator applications, the movable indicator
points to the temperature at which the circulator will start.
On combination low limit and circulator applications,
the movable indicator points to the temperature at which
the low limit will stop the burner and permit the circulator
to run.
CAUTION
!
Thermostat
High
Limit
Burner
Motor
Line Voltage
Oil Burner Control
Combination
Low Limit-
Circulator
Control
Circulator
Relay
Type
809A-189
Ignition
Transformer
1
2
T
T
4
3
4
3
B
B
R
W
W
1
2
Hot
Neutral
120V