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Installation Principle of an Electric Water Heater

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Electric Water Heater of latest generation

chauffe eau electrique thermor

Install the water heater in a ventilated room in which the temperature will always be between 4°C and 35°C, close to the draw-off points (shower, sink).

The water heater according to the case and needs is composed of:

  • mounting plates or U-bolt to peg to the wall
  • universal tripod (or quadripod) on which the heater is placed, itself being fixed to the wall
  • ceiling mounting system
  • strapping that girds the water heater

Follow the instructions regarding the strength of the support structure material (wall) and the fixings specific to heavy loads.

From an electrical standpoint, it must be connected to the cable outlet (not a socket), the cable is of section 2.5 mm² (phase/live, neutral, earth) itself connected to a circuit breaker 16A and a differential of 30 mA. It should be installed preferably in the volume 3 of bathrooms unless the bathroom dimensions do not allow that (volume 2 or 1 depending on conditions).

Some water heaters can be installed horizontally.

Meet the minimum volumes required between the water heater and the walls and/or objects (2 cm minimum with any object, 40 cm in the lower part).

installation chauffe eau salle bain volumes 1 2 3

Connection diagram and essential accessories

schema installation chauffe eau

safety unit connection diagram Source Thermor

From a hydraulic point of view, the water heater cannot be installed independently. Additional accessories, rarely provided, are necessary for safe operation: a safety unit, a deflector equipped with a funnel siphon kit, a thermostatic control valve, 2 dielectric unions and sometimes a pressure-reducing valve. In order to maintain an easy access to these equipments you must always provide a free space of about 40 cm in front of the water heater.

1) The safety unit is designed to limit the pressure when the water heater is heating.

2) The thermostatic control valve is a safety device that aims to provide mixed water of limited and constant temperature to the tap. It’s an anti-burn accessory that also limits scale clogging.

3) The 2 dielectric unions (DU) are to be placed directly on the inlet of the water heater. Their function is to remove “the battery effect” associated with the use of 2 metals (copper, alloy, steel…) that drives and accelerates the corrosion by circulation of a residual current. For example, the “cold water” inlet of the water heater (connecting piece) if is steel it’s connected to the safety unit (brass). The removable union therefore overrides the “battery effect” and the circulation of currents called “vagabonds” related to poor earthing. These unions are recommended by the D.T.U. 60.1 standard as regards sanitary works in buildings.

rid raccord dielectrique

DU: dielectric union. Source: Watts industries

4) The pressure reducer is an accessory to be installed at the outlet of the water meter (main cold water shut off valve of the dwelling) in the case the water pressure of the housing exceeds 5 bar (5 MpA). Its purpose is to prevent the safety unit valve to open unintentionally when the water heater is not operating.

Optional) The expansion tank is an accessory allowing to increase the pressure in the water heater before the safety unit opens to discharge the water into the sewer. It allows to limit water losses and to reduce wear of the safety unit.

Optional) If the water heater is installed above accommodation spaces (attic, ceiling, etc.), it is mandatory to install a water collecting container connected to the sewer. In case of a leak you avoid major damage.


Water Heater Maintenance

It is recommended by the manufacturers:

  • to manipulate the safety unit every month otherwise the limescale may damage the water heater (and void the warranty).
  • to control the magnesium anodes every 2 years (to be replaced if the diameter is less than 10 mm).
  • to treat water with a water softener in the regions where the water is hard (hardness must remain under 15°f).
  • to use water whose levels are normal (chlorides, sulfates, calcium, resistivity and TAC).

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