Flame Sensor - Aqua-Hot 400 Series Service Manual

Flame Sensor

Function:
The purpose of the Flame Sensor, is to monitor the flame of
the propane burner and verify that it is burning properly.
The flame sensor turns the heat from the flame into a mili-
volt signal that the propane burner controller senses.
Replacement Indicator:
Replace the Flame Sensor if it fails to operate properly or is
damaged.
Troubleshooting Procedure:
NOTE: The interlock switch will prevent the Propane-Burner
from operating without the access cover intact; therefore,
the switch will need to be manually pressed during this trou-
bleshooting procedure.
1. Flame current is the current which passes through the
flame from the sensor to ground to complete the prima-
ry safety circuit. The minimum flame current necessary
to keep the system from lockout is 0.7µA micro amps.
To measure flame current, DISCONNECT INPUT VOLT-
AGE, then insert a 0-50µA DC meter and capacitor in
series with the sensor electrode and wire per Figure
Meter should read 0.7µA or higher while flame is estab-
lished. If meter reads below "0" on scale, meter leads
are reversed. Disconnect power and reconnect meter
leads for proper polarity.
NOTE: A defective flame sensor will usually allow the burn-
er to ignite for approximately 2-5 seconds, and then shut
down into default mode.
Figure 65
65.
© Aqua-Hot® AHE-400-P01 Service Manual Rev.B June 2014
Section #: Title
Propane-Burner Components
Flame Sensor
p.
69