TM081 Rheem 834 Series Hydroelectric CFGWH Service Instructions
REV: AA Issued: 22/02/17
This document is stored and maintained electronically by Rheem Technical Support. All printed copies are deemed uncontrolled.
17
Gas Valve
: An electromagnetic valve designed to control gas flow to the pilot and main
burner. All heaters utilise a CK-690 gas valve which is equipped with an internal gas
regulator, pilot solenoid valve (SV1) main burner safety solenoid valve (SV2), main burner
solenoid valve (SV3) and motorised actuated solenoid valve (MASV). Also refer to 'Gas
Valve' on page 18.
Hot Water Outlet Temperature Sensor:
A thermistor type sensor utilised to detect the
heater's hot water outlet temperature i.e. the resistance value of the sensor will change
according to the detected water temperature. The sensor is installed in a well in the hot
water outlet and is connected to the temperature controller which monitors the resistance
value of the sensor to determine the heater's outlet water temperature. Also refer to
'Testing the Hot Water Outlet Temperature Sensor' on page 39.
Overheat Switch:
An electromechanical device (bi-metallic switch) designed to shut down
the heater in case of excessive temperature. The overheat switch will open circuit (trip)
when the detected temperature reaches 95°C ± 4.5°C and must be manually reset by
pressing and releasing the reset button on the overheat switch once temperatures have
fallen to
≤ 90°C. The overheat switch is a safety backup in case the hot water outlet 85°C
shut down (software) function does not operate. Also refer to 'Resetting the Overheat
Switch' on page 46.
Pilot:
A small burner utilised to light the heater during the ignition period. The main burner
cross lights from the pilot. 834 Series Hydroelectric Instantaneous Gas Water Heaters
have an interrupted pilot i.e. the pilot is lit during the ignition period and is extinguished
during normal operation of the main burner.
Main Burner:
The main burner is located at the bottom of the heat exchanger assembly
and is where gas delivered by the gas valve is combusted. The gas mixture flows out of
the perforations on the top surface of the burner bars where it is combusted providing an
even burner flame.
Burner Manifold:
The burner manifold directs gas from the gas valve to the burner. The
burner manifold has a series of injectors that deliver gas to the rear of the burner bars.
Heat Exchanger Assembly:
The heat exchanger assembly is where heat transfer occurs.
The assembly is comprised of a burner, fin tube and flue collector. The burner is located at
the bottom of the heat exchanger and the fin tube is located above the burner. Water flows
through the fin tube where heat transfer occurs from the burner flame. The fins on the tube
bundle help to capture heat whilst allowing hot flue gasses to flow through to the flue
collector where they are directed to the flue outlet by natural draught.
Air Intake Louvre / Flue Terminal:
The air intake provides air for combustion whilst the
flue terminal provides a point of discharge for combustion gasses.
Pressure Relief Valve:
The PRV provides pressure relief in case of system over
pressure. The PRV is located on the hot water outlet and also acts as a drain plug.
Rating label:
The rating label details the model number, serial number, gas type, burner
pressure and other heater specifications. The rating label is located on the right side of the
water heater.
