Service manual

06/2010
Section 2.1 Description of Operation ShowerMate
Note: The next 8 steps take place in 3-5 seconds.
 The flow meter senses the water flow & sends a flow signal to the green control
board.
 The green control board sends 12 VDC through the orange wire to the pressure
differential switch and on to the black relay that powers the power vent blower.
 The relay closes the 12VDC contacts to start the blower.
 Fluing is proofed by the vacuum tube that runs from the blower to the pressure
differential switch.
 The pressure differential switch contacts close, sending 12 VDC to the spark
ignition module via the orange wire.
 The Ignition module simultaneously affects a spark through the heavy yellow wire
to the spark ignition probe over the burner and sends 12 VDC to the combination
gas valve via the blue wire.
 Ignition of the burner’s element is effected and the flame is proofed and monitored
through the same yellow wire by the spark ignition module.
 The green control board sends DC voltage to the modulating gas valve for one
second to effect flame cross-over to all burners.
 The micro-processor on the green control board monitors water flow with the flow
meter and temperature with the three thermistors twice / second and varies voltage
0 – 12 VDC to the gas modulating valve, varying gas flow to burner in order to
maintain constant temperature output.
 Burner remains lit as long as water flow continues, but if flame is extinguished for
any reason, the gas valve will shut off in less than 1 second and re-ignition will be
attempted.
 When water is turned off and the water heater no longer senses flow the heater
shuts down to standby mode.