TECHNICAL
57
The position of this valve
in the system should
be such that the whole
installation, not just the
geyser, is protected by it.
This will thus also supply
balanced water pressure
to all the mixing points in
the system.
Once the geyser starts to heat up the water, the pressure in the system will start to
increase. This extra pressure cannot push back into the mains supply line as the
pressure valve will be in the closed position. To protect the system from the raised
pressure an expansion release valve must be fitted.
Some pressure reducing valves are fitted with an extra function and can release the
built up pressure. This valve is then normally referred to as a Pressure Control Valve. If
the reducing incorporates such an expansion port, no extra expansion valve needs to
be fitted. Care needs to be taken however, that no isolating valve is allowed to be fitted
between the geyser and the expansion valve.
Two other valves that need to be fitted are
Vacuum Breakers. These valves need to be fitted
on an anti-syphon loop so that the system is
vented at the highest point in the system. Any
water that is higher than the vacuum breakers
can, and will be syphoned from the system if the
mains pressure drops below system pressure.
The hot water system
must also be protected
from overheating, by a
Temperature and Pressure
Safety Relief Valve being
fitted to the hot water
cylinder. This valve will let
hot water out of the hot
water cylinder and allow
cold water to enter the tank
so that the temperature in
the tank always remains
below boiling point.
Due to very hot water being
expelled from the tank we
have to make sure that the
valve is vented in accordance
with SANS10254. The regulation for the installation and use of these valves is covered
in SANS10252 part 1. It is of utmost importance that we familiarise ourselves with
these regulations.
It has often been said that knowledge is power, but by us using our knowledge
correctly and by acting responsibly when we do any installations, we can do our part in
the conservation of this valuable resource, our water. PA
August 2019 Volume 25 I Number 6
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