Installation guide

OPERATING INSTRUCTIONSSECTION 5
When properly installed and adjusted, the heater will require minimal attention. Should it
become necessary to completely drain the heater, follow instructions given in Section 4,
Commissioning.
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 burner in an overheat condition. When the water has cooled
sufficiently, the manual reset on the ECO needs to be depressed to allow the heater to be
re-lit. If the burner shuts down and is associated with high water temperature, the ECO is
probably operational and the cause of overheating should be investigated.
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 results 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 which senses abnormally hot
water and shuts down the main burner until the water cools. Most modern commercial
pipe installations include a pumped secondary return system which keeps hot water
moving continuously throughout the heater. This stabilises temperatures in the water heater
tank and throughout the pipe system.
ECO
(ENERGY CUT-OFF)
TEMPERATURE
STRATIFICATION
(STACKING)
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