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TECHNICAL
Geysers in parallel
The following is a summary of an IOPSA/PIRB Tech Talk by Adriaan
Myburgh, edited by Eamonn Ryan, relating to pitfalls and potential
mistakes in installing geysers in parallel.
Multiple water heater installations are predominantly
used in commercial or industrial applications where a
high volume of heated water may be required during
peak hours, or where insufficient planning was done
to supply hot water to a new build in order to comply
with XA 2.
There are two main methods of interconnecting these hot water
cylinders:
• Series connections
• Parallel connections
This Technical article will deal with Parallel connections.
In a series connection, cold water is fed through each tank –
one after the other – with the hot water outlet from the first tank
becoming the cold supply to the next tank. The installations of
geysers are governed by a single regulation, SANS 10254:2017:
The installation, maintenance, replacement and repair of
fixed electrical storage water heating systems. This document
covers the safe installation of new and replacement fixed
electric storage water heaters, complete with all the relevant
and applicable safety and hydraulic control units. However, this
standard does not cover the sizing or hydraulic design of the
storage water heating system or the design and installation of
industrial hot water systems.
In other words, it is for simple off-the-shelf units installed
onto a client’s premises. Section 4.1.1.2 of 10254 states,
“Where some of the provisions of this standard cannot be
applied, the installation shall comply with the details given
in a rational design developed by a professional engineer on
acceptable installation drawings, and such rational design
shall not compromise the safety
and performance principles
incorporated in this standard.”
they are interconnected, but when they are stand-alone geysers
as well. Even where it is signed off by a competent person as to
the design, a CoC must still be issued by the plumber as to the
materials and workmanship.
The regulation ‘5.6 Mains shut off’ applies to a geyser
installation in parallel: “5.6.1 For ease of maintenance, the
inlet pipe to a pressure control valve and to a float valve
(water storage tank cistern-type or cistern-fed heater) shall be
furnished with an isolating valve.
“5.7 Vacuum control valves: In closed systems and in valveoperated
vented systems, vacuum control valves shall be
installed on both hot and cold water pipes to and from the
heater to ensure that both lines and the water heater are vented
and that siphonage is prevented.
“5.8 Expansion control valve on cold water supply: When an
expansion control valve is installed on the cold water side
of the water heater, it shall be installed downstream of any
isolating valve, gate valve, non-return valve or any other flowcontrol
device.
Myburgh emphasised that when doing multiple geysers in
parallel (or in series) the above regulations apply to each unit –
not just the first one but leaving the rest.
This means if a plumber gets a job falling outside the scope
of this standard, he/she needs to ensure the job is based on
drawings, even if just the manufacturer’s layout of how the
system is to be connected, and that the plumber is satisfied
with the drawing. The following being an indication of what an
installation could look like, but it is not a design.
Myburgh described the reason
for the Tech Talk as being the
following sub-section 4.1.1.4:
“On completion of the installation,
a certificate of compliance
from the professional body for
plumbers registered in terms of
the relevant national legislation
[in this instance the PIRB],
shall be issued to the owner of
the installation or to the body
requiring such a certificate.”
As a plumber, the maximum size geyser that he can install is 450
litres, under the scope of his qualification. This means if a plumber
is installing geysers in a series that is in aggregate more than 450
litres, at some point another professional competent person has
to sign it off based on an approved design. This not only applies if
He highlights potential problem areas: “In the position of the
shut-off valves each cylinder needs to be isolated on its own
in that system. Failure to do so would negate the purpose of
the entire job of giving a client a greater volume of hot water
at one time.
www.plumbingafrica.co.za @plumbingonline @plumbingonline @PlumbingAfricaOnline October 2020 Volume 26 I Number 08