Standard Range; Hi-Flo Range - andrews 32/143 Installation Manual, Operation And Service Manual

OPERATION
When properly installed and adjusted, the heater will require minimal attention.
Should it become necessary to completely drain the heater, close the cold water inlet valve
and open a hot water tap to allow air to enter the system. Fit a suitable hose to the drain
cock and open.
Whenever the heater is filled with cold water, condensation will form on the storage vessel
surfaces when the burner is lit. This is normal and will disappear when the heater warms up.
The gas control fitted to the heater has a built-in limit thermostat (ECO). In the event of
high water temperature, the gas supply will be shut off automatically.
The high temperature condition must be identified and rectified before the heater is relit.
The gas control is fitted with a recycling type ECO. This means that, once the water has
cooled sufficiently, the ECO circuit will close and allow the heater to be relit.
A replacement gas control valve must be an identical model with the same code number.
Permanent Pilot Models, Operating Sequence
1. With the pilot lit, the solenoid coil holds the inlet gas port on the gas valve open.
2. The knob on the gas valve is set to the ON position.
3. The control thermostat is set to the desired water temperature, 49ºC to 82ºC (120ºF to
180ºF). To set the thermostat, remove the outer cover and turn the adjustment dial to the
required temperature.
4. The thermostat should now be in a closed position allowing the current generated by the
pilot-energised thermopile to open the main burner valve.
5. The gas valve has a slow burning feature. Burners will light several seconds after setting
the thermostat.
6. Burners will continue to heat water until the preset temperature is reached. As the
thermostat opens, the thermopile current is interrupted and the main gas valve will close.
Auto-Ignition Units, Operating Sequence. Hi-Flo and Standard Range
1. When the control thermostat senses too-cool water, a signal is sent to the control
sequence unit.
2. The flue damper unit is de-energised and thus allowed to open. (Hi-Flo only).
3. When the flue damper is fully open, gas is allowed to pass to the pilot and simultaneous
ignition begins. (Hi-Flo only).
4. When the pilot flame is established, the main gas solenoid is allowed to slowly open and
the main burners or burner is lit.
5. When the control thermostat is satisfied, both pilot and main gas solenoids are closed.
6. The damper motor is energised and the damper closes. (Hi-Flo only).
ECO (Energy Cut-Off)
The heater is equipped with an ECO (Energy Cut-Off) device, fitted to the control
thermostat. It is a temperature sensitive switch which opens at high temperature, shutting off
gas to the burners, including the pilot in an overheat condition. If the pilot goes out and is
associated with high water temperature, the ECO is probably operational and the cause of
overheating should be investigated.
Temperature Stratification (Stacking)
When small amounts of hot water are drawn repeatedly, the thermostat responds to each
feed of cold water and activates the main burners. Each time this occurs, more heat may be
put back in the tank than was drawn off. As this continues, water in the upper level of the
tank gets hotter than the thermostat setting. This hotter water does not mix completely with
the cold inlet water but rises in a 'chimney effect' to the top of the tank. Many repetitions of
this over a short time period result in accumulation of excessively hot water in the upper part
of the tank, even when the thermostat control is within limits. This is known as stacking.
To counter this condition, an upper thermostat phial is fitted (not on Model 32/143) which
senses abnormally hot water and shuts down the main burner until the water cools. Most
modern commercial pipe installations include a circulating pump which keeps hot water
moving continuously throughout the heater. This stabilises temperatures in the water heater
tank and throughout the pipe system.
39
SECTION 5
STANDARD
RANGE
HI-FLO
RANGE
HI-FLO AND
STANDARD
RANGE
AUTO IGNITION