Operation Of Thermostat Sensor - Monessen Hearth DEB20 Installation And Operating Instructions Manual

OPERATION OF THERMOSTAT SENSOR

1.Follow millivolt lighting instructions on lighting plate attached to unit or in homeowner's manual.
2.With control knob in the "ON" position make sure the ON/OFF switch is in the "OFF" position. See Figure 25.
3.The unit is now being controlled by the thermostat sensor. The sensor will now cycle the burners on and off. You can adjust
how often the unit cycles by turning the control knob on the sensor.
Figure 25 - Control Knob in "ON" Position and ON/OFF Switch in "OFF" Position
CHECKING SYSTEM OPERATION
The milli-volt system and individual com-
ponents may be checked with a milli-volt
meter having a 0-1000 mV range. Conduct
each check shown in chart below by con-
nection meter test leads to terminals as
indicated.
A. COMPLETE MILLI-VOLT SYSTEM CHECK
("A" Reading - Thermostat contacts CLOSED - Control Knob "ON" - Main burner should turn ON)
a. If the reading is more than 175 milli-volts and the automatic valve still does not come on, replace the control.
b. If the closed circuit reading ("A" reading) is less than 175 milli-volts, determine cause for low reading, proceed to
Section B below.
B. Thermopile Output Reading Check
("B" Reading - Thermostat contacts OPEN - Main burner OFF)
1. Check gas pressure to the unit. If gas pressure is within minimum and maximum on data plate, then check pilot
voltage, 500 milli-volts minimum. If the minimum milli-volt reading is not obtainable, replace pilot.
44D0060
Control
Knob
CHECK
TEST
ELECTRICAL WIRING (MILLI-VOLT)
ON/OFF
Switch
� �
� �
� �
� �
� � � �
� �
�
� �
� �
� �
� � �
T-Stat
Sensor
TO
TEST
A COMPLETE
SYSTEM
B THERMOPILE
OUTPUT
� �
� �
� �
�
CONNECT
METER THERMOSTAT
LEADS TO CONTACTS
TERMINALS
2 & 3 CLOSED
1 & 2 OPEN
METER
READING
SHOULD BE
MINIMUM
175
MINIMUM
500
25