64
TECHNICAL
Key considerations when
upgrading your sanitary cistern
to a mechanical flush valve
Identifying and using the correct hardware are
essential when planning your installation.
By Patrick Gordon
Firstly, the mechanical functionality of the two differs
completely. The cistern holds an amount of water at
a level higher than the toilet pan. This creates a head
of water that generates the pressure needed to flush
the toilet bowl efficiently. Because the demand on
repeated flushes is normally very low, the refilling
time is not a huge problem.
into the wall and is a lot more aesthetically pleasing. This
type of cistern is very sleek and even though it is built into
the wall, is fully serviceable from the front. By removing
the actuator plate, all the internal components can be
removed/serviced. These tanks come complete with an
internal isolating valve to facilitate easy maintenance. PA
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A mechanical flush valve does not have a stored head
of water but depends on the water supply that it is
connected to. This requires a suitably sized pipe design
but allows for repeated flushes without having to wait for
the tank to fill up.
Installations such as public ablutions at shopping centres
(especially at the cinemas and food court), sports
stadiums, high vandalism areas, and train stations are
high traffic areas where the toilets have to service high
demand, especially at certain times. Here a mechanical
flush valve is ideal. Most of the sensitive areas where the
installation is dependent on having water on demand 24
hours a day, will have water being supplied via a header
tank on a stand, which in turn is topped up from the
municipal water supply when available. This in turn would
require an installation with larger pipe sizes to facilitate
the demand of water flow without too much friction loss.
This would also require a mechanical flush valve that will
operate at these low-pressure installations.
One of the reasons why a customer would require a
mechanical flush valve is if they have limited space in
the toilet cubicle. The alternative type of installation for a
low-traffic area would be a concealed cistern that is built
March 2018 Volume 24 I Number 1
Patrick started in the plumbing
retail business in 1985
with the Boumat Group.
In 2000, he moved from
retail to manufacturing and
joined Cobra Watertech as
a call centre administrator.
He rapidly moved up in the
company and served as
product support manager
/ product development
manager and in 2005, he
was asked to take over the
product support department
nationally. He then qualified
as a facilitator and assessor.
When LIXIL Africa was formed
and they had to train all the
companies — Grohe, Cobra,
Isca, Vaal, Plexicor and Libra
— the training department
was expanded.
Most cistern installations have 15mm (1/2”) pipes
connected to them. This is not suitable for mechanical
flush valve installations on toilets. A mechanical flush
valve would typically not be used in a domestic installation
as they are normally not very aesthetically pleasing. For a
larger (shopping centre type) installation, larger pipe sizes
are usually present and the small supply pipes can be
changed to larger ones without incurring major expenses.
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Patrick Gordon
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2.
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Installations that are dependent on having water
on demand 24 hours a day, will have water supply
via a header tank on a stand.
A mechanical flush valve.
Components of an in-wall cistern.