• Electric Calorifiers
• Materials of Manufacture
• Insulation
• Ancillary Equipment
• Ormandy Type References
• Sizes and Dimensions
• Hot Water Demand Requirements
• Immersion Heaters
• Control Panels
• Unvented Systems
• Immersion Heater Maintenance
• Element Failure Checks
• Fault Finding Chart

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Electrically heated calorifiers with RCD protection may experience nuisance tripping especially if personnel protection levels are installed. Generally RCD level protection should be set for equipment protection level only.

Immersion heaters should be checked for the following:

1. Earth leakage from live to earth should not be less than 500,000 Ohmns.
2. Check phase to neutral resistance. (Resistance readings should be checked against the immersion heater test certificates.)

It is extremely rare for new immersion heaters to show incorrect resistance readings. Elements with broken coils must be replaced immediately. Low insulation readings however may be caused by the ingress of moisture. If one or two stages of a large immersion heater show low insulation readings the following procedure is recommended:

1. Isolate the faulty elements from the rest of the immersion heater by switching the mcb's off or removing the relevant fuses. (All three phases of a stage must be isolated.)
2. Allow the calorifier to heat the stored water up to 65°C.
3. After 48 hours at temperature, check the readings of the isolated elements. If they have improved to a satisfactory level the stages can be placed online.

If the readings still indicate a fault further investigation is required to identify the failed element(s). Further investigation requires the removal of the busbars. Each element should be checked in turn. Faulty elements can be dried in an oven at 200-240°C. If the insulation readings do not improve after 24 hours the element should be replaced. Element resistance test. Element insulation test.