80 TECHNICAL
How does SANS 10254:2017 impact on existing and new installations?( Part 2)
Most of us know that SANS 10254 applies to all installations( new, maintenance, and repairs), but how does the new 2017 version affect previously compliant installations?
By Patrick Gordon
Patrick Gordon
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.
Contrary to popular belief, an under / over-basin geyser is still subject to the SANS installation regulations and thus needs to be installed accordingly. Anybody who has tried to install these units as a pressure vessel will know that it is impossible.
What is the alternative option? If you look at Figure 1, you will notice that SANS has a specification for an open-vent heater installation. The first thing that you will notice is that the drawing does not call for a pressure-reducing valve or an expansion relief valve. This is because if installed according to the drawing, it is installed as an open-vent installation. This means that the flow is regulated before the heater and the outlet does not get restricted( open outlet and thus no pressure in the heater).
This requires that a special mixer is used for this type of installation. You can recognise this mixer by the fact that it has three connection hoses instead of the usual two.
With this type of installation, no vacuum breakers are needed and also no TP & S. A thermostat, however, is still required, and this is usually integral in the housing of the heater.
Figure 2: Typical open vent mixing control valve unit for under-sink water heaters.
Also note that you need to notify your customer / user that while the heater is heating up, there will be a drip from the mixer outlet. This is due to the expansion taking place during the heating process.
The ideal use of this type of installation is where you have a basin at the end of a long dead leg. You now only need to supply cold water to this point and with the push through installation, it has instant hot water for use.
Note, though, that it only holds a limited amount of hot water and has a re-heating time. It is not an instantaneous water heater. The electrics of these units only need a standard 15 amp plug point to be supplied as the heater comes with a normal 15 amp plug top.
Figure 1: How the main supply and water heater connect with the valves and the drip tray.
Remember that with this being part of SANS 10254, it applies to existing installations, so when issuing a CoC, make sure that you check all existing installations of these units. The only compliant push through heater installations that I have seen are the ones that I have been involved with personally.
So to all of you doing geyser installations, safe plumbing. PA
October 2018 Volume 24 I Number 8 www. plumbingafrica. co. za