Page 267 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

2 Storage water heater

1 Immersion water heater
As is apparent from the name, it is dipped in the vessel containing water for heating. There is a heating element
in the brass chromium plated water-tight tube and insulated from it with an insulating mate¬rial like plaster of
paris. There is no wastage of heat in it, so its efficiency is greater than other type of heaters. It is a portable water
heater, as shown in Fig. The immersion heaters are manufactured in 250, 1000 and 1500 W ranges. The 250 W
immersion heater is used for heating water for shaving purposes only.

2 Storage water heater

It consists of a double-walled reservoir known as the cistern, a heating element and a thermostat. It is not a
portable water heater and is fixed on the wall where it is to be used It can be further divided into two classes:
i Non-pressure type water heater

ii Pressure type water heater
i Non-pressure type water heater
Figure shows a non-pressure type water heater. It is used at places where hot water is required at one service
point only.

It has only one outlet for water without a stop cock. The water is controlled only from inlet side by a valve as shown
in Fig. It consists of a double-walled chamber. The space between the two chambers is filled with a heat insulating
material like glass wool or cork. The heating chamber generally consists of tinned copper and the outer covering
of lead coated steel. This outer coating is given a final coat of white enamel paint. The inner chamber has a drip
device, a thermostat for controlling the temperature of the water and a heating element erected vertically. The
anti-drip device is connected to the outlet pipe which helps in having a quick cut-off of hot water.
When the inlet valve is opened, it allows an equal quantity of hot water into the outlet pipe. The pressure inside
the chamber does not develop because the outlet valve is always opened.
It should be always remembered to earth all the metal coverings of the water heater.
ii Pressure type water heater
When the hot water is needed at more than one servicepoint and only one heater is to be used, then this type
of water heater is used only. This kind of water heater gets water supply through the cistern (i.e., reservoir) which
is connected to the water mains through a controlling float valve.The power consumption of a 25-litre bathroom
geyser is either 1000 or 1500 W.

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CITS : Power - Electrician & Wireman - Lesson 101-103