Flammable Vapour Sensor - GSW 71189 Installation And Operating Instructions Manual

Flammable Vapour Sensor

When using a gas fired water heater there is a risk of flam-
mable vapours entering the combustion chamber, being
ignited by the burner flame and causing a flashback. In
order to detect such flammable vapours before they enter
the combustion chamber, this water heater is equipped with
a flammable vapour sensor (FVS). It is a chemical-absorp-
tion based sensor that is connected to the gas control/ther-
mostat (see Figures 22 & 24). When exposed to flammable
vapours it will trigger the control to stop the flow of gas and
enter the FVS lockout state. While in the FVS lockout state
the LED on the control will flash the gas lockout code.
(Refer to the "System Error Codes" section of this manual
for an explanation of the codes applicable to the control
installed on your water heater.) If this error occurs, check
around the water heater for sources of chemical contamina-
tion such as: flammable vapours including gas vapours, sol-
vents, paint and thinners as well as sources of water and
detergents. Remove any such sources, check the sur-
GAS CONTROL
SWITCH (ON)
OUTLET TO MANIFOLD
DOOR ASS'Y (UNDER)
GAS CONTROL-VIEW OF ELECTRICAL
CONNECTORS, WITH COVER REMOVED
Figure 22 Gas Control/Thermostat Details and Wiring Diagram (Robertshaw)
3/4" NPT. WRAP
WITH TEFLON TAPE
(2 WRAPS MIN.)
GAS VALVE
SOLENOID
CONNECTOR
FLAMMABLE VAPOUR
SENSOR 2 PIN
MOLEX CONNECTOR
QUICK CONNECTS
FOR POWER SUPPLY
AND IGNITER
TERMINAL BLOCK BLOWER
AND JUNCTION BLOCK 8
PIN MOLEX CONNECTOR
GROUND CONNECTION
HIGH LIMIT
SWITCH
* ROTATE LEFT (CCW)
TO REMOVE
Figure 21 Flammable Vapour Sensor (exploded view)
INLET
PRESSURE
PORT
160F MAX. DIAL
GAS INLET
1/2" NPT
SYSTEM
STATUS
140F MAX. DIAL
CODES
AIR PRESSURE
SWITCH
GND
L1 N
– 18 –
SCREW
COVER*
FLAMMABLE
VAPOUR SENSOR
(PULL TO REMOVE)
LED INDICATOR
GAS CONTROL-VIEW FROM GAS INLET
WITH TEMPERATURE DIAL REMOVED
FLAMMABLE
VAPOUR
SENSOR
IGNITER
BLOWER
CONNECTOR
GAS VALVE
SOLENOID
POLARITY SENSITIVE DO NOT MIS-
MATCH WIRING. FAILURE TO CONNECT
CORRECTLY WILL PREVENT THE UNIT
FROM FUNCTIONING PROPERLY.
MOUNTING
BRACKET
MANIFOLD
PRESSURE
ADJUSTMENT
(REMOVE
DIAL FOR
ACCESS)
OUTLET
PRESSURE
PORT
(UNDER)
FLAME
SENSOR