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Ask Patrick

If I have an isolating valve at the geyser, what else should I keep in mind?

There is a basic rule that must be kept in mind with all geyser installations. You are not allowed to have an isolating valve between the geyser and the Pressure Relief Valve. In most installations that have been correctly plumbed for balanced pressure the Pressure Reducing Valve and the Pressure Relief valve is situated outside the building to facilitate ease of installation. If a isolating valve is now placed near the geyser, this would cut off the path of relief for the geyser. This installation would not comply to SANS 10254. How could I keep the installation as is but make it compliant? This is done easier that what you would think. All you must do is to fit a Pressure Relief Valve between the geyser and the isolating valve. Just remember that this valve must be fitted over the geyser tray and must be piped out according to the rules set out in SANS 10254.


Must all installations have balanced water?

SANS 10254 says that the water pressure SHALL be balanced at all mixing points. Most installations these days have at least one if not more points where the water is mixed before leaving the final outlet. You may say, “I don’t have any mixers in the installation”. But ask yourself, is there a shower installed? Even though you have two separate stop taps the water is still connected via a “T piece” before reaching the terminal point, namely the shower rose. This is a mixer and the water must be the same dynamic pressure at the hot and cold water stop taps. Only installations where there is no shower and only separate pillar and bib taps throughout the whole installation may be unbalanced. However, it is still recommended that you always plumb for balanced pressure to all terminal points as you do not know when a DIY person may change the taps at a basin to a mixer.


How can I see if the water pressure is balanced?

It may not be easy to assess whether a system has balanced pressure on face value. The best way to find out is to utilise a pressure gauge, and to physically check the pressure at each tap. If you do not have a pressure gauge, a quick yet rudimentary way of checking if to open both taps, on the hot and cold side, and assess if the flow is the same on both lines. This may not be the most accurate method, and can be very messy. Always account for other restrictions that maybe influencing the pressure on the line.

Are you allowed to install a Pressure Control Valve upside down?

This is a common question that is often a bone of contention. When looking at the physical operation of the valve, there is not up nor down, with the valve being capable of operating at any angle. However, SANS 10254 clearly states:

Discharge from valves The discharge pipes from expansion control and safety valves shall be so installed that:

1)They are inclined downwards continuously to their outlet.
2) Drainage of both valve and piping is ensured.
3) Blockage due to freezing or foreign objects is prevented.

Keeping this regulation in mind, the expansion valve must be positioned ensuring that it inclines downwards and that drainage of both the valve and the piping is present. Each manufacturer has a different valve configuration and installation features that must be kept in mind so that complete drainage of the valve and the piping is ensured. To summarize, no valve has an up or down, but the position is determined by the relief outlet of each valve.

Why is it now required to install two Vacuum Breakers when it was never a requirement before?

Due to Vacuum Breakers failing on occasion and causing damage it is important to look for ways to minimize the risk. Here are some old types of installations:


When the main water supply to the house was in the form of a heater tank which provided the dwelling with some pressure, all that was necessary was to have the vertical pipe that stood slightly higher than the supply tank on the cold-water side. Alternatively if the tank was on the roof, the pipe would have to be routed back into the top of the tank. This mechanism acted as a expansion relief valve as well as a vacuum breaker. As soon as negative pressure applied to the inlet all the water would be pulled from this riser pipe and allow air to be sucked in. In summary, it created a combination expansion relief and vacuum breaker. Limitations to this system were that there was little pressure in the Hot Water Cylinder which led to the demand for a closed pressure system.


Many will remember the old Latco “Flying Saucer”. Here you could have higher mains pressure and reduce the hot water pressure for an unbalanced installation. Remember in the old days we mainly used single taps and watering can shower roses so balanced pressure was not an issue. You could either have a high pipe, like in the previous type of installation, or use the Latco Relief valve. So where is the Vacuum Breaker now? Few people realize that the Latco relief valve served a dual purpose and that it was a relief valve and a vacuum breaker. A very effective one I might add. So, from the inception of the pressure system, we have been using two vacuum breakers and until we can find a better way of doing these functions, we must continue to do so. Let us look forward to the progress in technology.

Does my valve stop being SABS compliant if I service it? Will I lose my warrantee?

How does a valve become SABS compliant? The manufacturer has designed and produced a product that complies to the minimum requirements set out by SABS Standards. They have also, hopefully, considered what the customers demand from such a product. Because of inhouse and external monitoring we already know what to expect when we buy this product. But how can we be sure that when we are finished working on the valve our expectations will still be met? We need to start with the basics and make sure that we fully understand the operating principles and performance specifications from the product. The easiest way to achieve this is to attend the training sessions that are offered by all reputable manufacturers. Not only can they teach you how the product works but also on how to maintain its integrity. The only way to make sure of future performance, and to get the manufacturers backing is to use the genuine replacement parts offered by the manufacturers. Some items may be sealed and unserviceable to ensure that its integrity is maintained. Become a specialist in the services that you offer, and you will get all the support that you need from the knowledge base that is present in the industry.