TECHNICAL
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“When looking at shutting off cylinders individually in parallel or in series you will require additional
expansion relief. In addition, the pipe work has to be exactly measured – otherwise the water will take
the shortest route and there will not be an even distribution of water. Regarding power supply, in a
normal geyser replacement you will have 2.5mm wire, with an isolator. When you start adding more
250 litre geysers together there will be considerably increased current drawn through it, so a qualified
electrician will be required to potentially upsize it.”
The above is how the system is supposed to look. Each cylinder has a shut-off valve and expansion relief
on either side downstream from the shut-off valve.
Points to consider when installing cylinders in parallel:
• The system operates equally well at both low and peak demand
• A bypass pipeline is not required as was the case with geysers in series
• All geysers that are to be part of this parallel connection are to be of exactly the same rating, same
size and same model
• Pipe sizing is not limited by the inlets and outlets of the cylinders – the size of the headers can be
increased
• SANS 10142 isolator per geyser: this may lead to increased wire thickness, possibly additional
breakers at the DB, and must be installed by a qualified electrician
• Being a rational design, the safety requirements are that all valves are to be labelled, special
operating instructions are to be provided and relevant warning signs are to be posted
• Most new electrical-only geyser installations will not comply with XA2 of the National Building
Regulations, so you have to make sure that somewhere in the system there is energy efficiency
In terms of geyser installations – be careful when signing off on these types of installation that may or
may not be compliant – by making sure they are compliant. Parallel connections of hot water cylinders
are not covered by SANS 10254:2017. Each installation will be unique, with different layouts, different
flow rates, space for working, demand from building occupants, and more. There is no one-size-fits-all or
generic design.
Myburgh notes that if a PIRB plumber is called in to replace one of a series of geysers, a CoC has to be
issued for that single geyser, and the plumber is also required to note on the CoC – and bring it to the
attention of the owner – any non-compliant issues relating to the remainder of the geysers. PA
October 2020 Volume 26 I Number 08
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