Flux is used during soldering of copper pipes to allow the solder to flow freely into the joint
and bond well with the base metals. It should however be properly cleaned off when done. When it is
not, it gradually corrodes the pipe and causes pitting and leaks. For more details see:
Wikipedia - Flux
Backdrop / Backfall
Drainage, weather sewer or storm water, relies on sufficient fall in the pipe to create
adequate flow velocities. If any section of the pipe runs uphill this will cause a constant
pool of liquid within the pipe. This then allows sedimentation of solids, even greater pooling, and
eventually a blockage. The causes of backfall could be poor installation or the gradual development
of roots below the pipe, for example.
Efflorescence
The formation of a crusty and/or powdery residue on especially concrete surfaces. This is due to the
deposit of soluble salts, usually leached from the mortar during the migration of water passing through
it. The water gradually evaporates but new salts are continually being added, causing the "flowering"
effect. The source of water must be found and corrected prior to any cosmetic work being carried out.
For more details see: Wikipedia -
Efflorescence
Expansion Relief
The Expansion Relief Valve is usually integral with the pressure reducing valve. When heated water is
drawn from the cylinder, the PRV allows cold water in to replace it at the regulated temperature. As this
water is then heated however, it expands, thereby increasing the pressure in the system. The Expansion
Relief Valve is responsible for releasing sufficient water, via a properly installed pipe, to keep the
pressure at the rated setting.
Galvanic Corrosion
An electrochemical reaction between two dissimilar metals or metal alloys. One metal will corrode
while the other is largely spared. For this process to exist, both metals need to be in contact with an
electrolyte, usually water. See "Sacrificial Anode" on this page for more details or the following link:
Wikipedia - Galvanic Corrosion
PRV
Pressure Reducing Valve, also referred to as a Pressure Control Valve. It is installed at the inlet
side of the geyser and reduces the incoming pressure to the appropriate level for the geyser. Usually they
are supplied with an integral expansion relief valve.
Sacrificial Anode
A rod inserted into the hot water cylinder, made of a metal alloy with a greater negative electrochemical
potential than the steel tank. The difference in potential causes the anode to corrode while the steel tank is
spared. These anodes need to be periodically replaced which, depending on water quality, would be every two to
four years. (Not all geysers however require anodes) For more details see:
Wikipedia - Galvanic Anode
SANS 10252-1
Water supply and drainage for buildings Part 1: Water supply installations for buildings. Document
available at: SANS 10252-1
SANS 10252-2
Water supply and drainage for buildings Part 2: Drainage installations for buildings. Document
available at: SANS 10252-1
SANS 10254
The installation, maintenance, replacement and repair of fixed electric storage water heating systems.
SANS 10400-A
The application of the National Building Regulations - Part A: General Principles and Requirements.
Document available at:
SANS 10400-Part A
SANS 10400-D
The application of the National Building Regulations - Part D: Public Safety. Document available at:
SANS 10400-Part D
SANS 10400-P
The application of the National Building Regulations - Part P: Drainage. Document available at:
SANS 10400-Part P
SANS 10400-R
The application of the National Building Regulations - Part R: Stormwater Disposal. Document available at:
SANS 10400-Part R
TP Safety Valve
Temperature and Pressure Safety Valve. This is installed into the geyser itself and is responsible for
ensuring the safety of the system by preventing over-pressure or over-heating situations. In the latter case
it prevents the geyser from literally exploding and releasing super-heated steam (up to 165 deg Celsius). This
can, and has, resulted in massive damage, serious injury and even death where the TP Valve was either not installed
or installed incorrectly. As such, it is the most important component in the system and must
be installed as per specifications! This would include the proper installation of a metal
discharge pipe, of the same diameter as the valve's outlet, to the exterior of the building and in a visible location.
Vacuum Breaker
One-way valve responsible for breaking the siphon that results when trying to draw water from your supply when
there is no incoming pressure. The resultant negative pressure could cause your hot water cylinder's inner lining
to crack and/or implode. One is installed at the top of the hot and cold side anti-siphon loops and should both be
installed over the geyser tray in case they fail and leak.
