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HOW YOUR WATER HEATER WORKS
8
147 MODELS
On/Off Operation
147 On/Off models are fitted with an electronic thermostat that operates the gas
control by switching its power on and off, so a constant temperature is maintained.
The thermostat is mounted on the control panel of the water heater and the protective
over temperature cut out is mounted inside the lower front cover of the water heater.
There is no need to switch the water heater off when it is not in use. The thermostat is
fully automatic and only allows the gas control to open when the burner requires gas for heating. To adjust the
thermostat settings refer to “Temperature Control
” on page 35.
The thermostat may flash “AH” (alarm high) and the current water temperature, or “AL” (alarm low) and the current
water temperature. This is not a cause for concern unless the temperature displayed is more than 10ºC above the
set temperature. Refer to “Diagnostic Features of Electronic Thermostat
” on page 9.
Hi/Lo Operation
147 Hi/Lo models are fitted with an electronic thermostat that operates the gas control
by switching its power from high fire to low fire and off, so a constant temperature is
maintained. The thermostat is mounted on the control panel of the water heater and the
protective over temperature cut out is mounted inside the lower front cover of the water
heater.
There is no need to switch the water heater off when it is not in use. The thermostat is fully automatic and only
allows the gas control to open when the burner requires gas for heating. To adjust the thermostat settings refer to
“Temperature Control
” on page 35.
The thermostat may flash “AL3” and 130, or “AL3” and -45. This indicates a failure of the water temperature sensor.
Refer to “Diagnostic Features of Electronic Thermostat
” on page 9.
BURNER IGNITION
All 109 and 147 Hi/Lo Models
The water heater utilises an automatic burner ignition system, which lights the main burner gas when the
thermostat registers a need for heating.
A hot surface igniter (HSI) heats up when there is a call for heating. When the HSI probe is up to temperature, a
valve opens allowing gas to the main burner and this is ignited by the HSI probe. Provided successful ignition of the
main burner flame is detected, the valve remains open to supply gas to the main burner. If the main burner fails to
ignite the ignition system will lock out.
147 On/Off Models
The water heater utilises an automatic burner ignition system, incorporating an automatic pilot burner, which lights
the main burner gas when the thermostat registers a need for heating.
A hot surface igniter (HSI) heats up when there is a call for heating. When the HSI probe is up to temperature, a
valve opens allowing gas to the pilot burner and this is ignited by the HSI probe. When successful ignition of the
pilot flame is detected, the valves open to supply gas to the main burner. If the pilot fails to ignite after two
attempts, the ignition system will lock out.