TM074: Stainless Steel Electric Water Heater Service Instructions
REV AB Issued: 07/16
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7
OPERATION
Water temperature is maintained via a thermostat switching the active conductor to an
electric immersion element positioned towards the bottom of the cylinder.
When the water temperature within the cylinder falls sufficiently, the thermostat contacts
close suppling power to the element.
Once the water temperature reaches the set point of the thermostat, the contacts open
cutting power to the element.
A double pole
‘manual reset’ over temperature cut out is incorporated into the thermostat
to provide additional protection in the event the controlling thermostat contacts fail. The
ECO contacts open between 80ºC and 88ºC.
COMPONENTS AND THEIR FUNCTION
Temperature and Pressure Relief (TPR) Valve:
A valve designed to provide automatic
relief by discharging water in case of excessive temperature, pressure or both.
Never fit a TPR Valve with a pressure rating greater than that indicated on
the product-rating label.
Pressure Limiting Valve (P.L.V.)
A valve that controls its outlet pressure to a predetermined limit.
Inlet Delivery Tube (Dip Tube)
A stainless steel tube installed in the cold water inlet of the water heater cylinder to assist
with stratification.
Diffuser
A device installed in the cold water inlet of the water heater cylinder to assist with
stratification.
Thermostat
A device, responsive to temperature, which controls the supply of electrical energy to the
element to maintain the stored water at the required temperature.
Over Temperature Energy Cut Out (E.C.O.)
A temperature-sensing device in combination with the thermostat that automatically cuts
off the supply of electrical energy to prevent excessive water temperature occurring. This
device will not reset automatically but may be manually reset once temperatures have
fallen to a safe level.
DETERMINE CAUSE OF OPERATION
.
Heating Unit (Element)
A tubular device containing an electric resistance element that converts electrical energy
to heat. Standard ratings are 1.8, 2.4, 3.6, and 4.8 kW.