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For two reasons – for safety and in accordance with the regulations. For the safety of those using a tap and to avoid injuries such as scalding, a tempering valve or TMV ensures the water being released from the faucet is not above 60°C (140°F) for tempering valves or 45°C (113°F) for TMVs. Additionally, in accordance with Australian regulations (National Plumbing and Drainage Standard AS/NZS 3500.4: 2003), various water installations are not permitted to deliver water at a temperature higher than 60°C/45°C for different fixtures.

When you turn the tap on in your home or workplace, you expect water at the correct temperature to be delivered – whether that be hot, cold, warm or something in between.

The wonderful little device that helps achieve the right hot water temperature is either a tempering valve or a thermostatic mixing valve, which can easily be mixed up but are actually two different things. To help you decipher between the two and figure out which one is best for your needs, take a read of the below information or give Brisbane Plumbing and Drainage a call on 1300 616 203 and we would be happy to assist.

We specialise in providing professional maintenance plumbing services – 24 hours a day, 7 days a week everywhere in Brisbane. If you have an emergency plumbing situation then contact our office and we will come to you ASAP!

A thermostatic mixing valve, or TMV, is a great little gadget that blends both hot and cold water together to achieve a particular, predetermined water temperature when delivering water through a faucet.

This means that all hot water system replacements should have a tempering valve installed. Some hot water system repairs do not require a tempering valve to be installed, but we suggest speaking to your plumber anyway to see if this is an option (it should be!).

Pressure vacuum breakers (PVBs) have a very similar mechanism to AVBs. The difference, however, is that PVBs have a spring-loaded poppet valve. Because of this difference, PVBs can be installed in systems where the potable water line (the line that’s protected) is downstream from the non-potable water source. These devices usually have test cocks where calibrated gauges are attached to ensure that the device is working properly. The most common application for PVBs is in preventing backflow in underground sprinkler systems.

If you have any further questions regarding tempering valves, TMVs or other hot water arrangements, give Brisbane Plumbing and Drainage a call on 1300 616 203 and we would be happy to discuss your hot water needs.

In cases when backflow will result in significant harm, these devices are considered suitable for the job – because they can effectively and reliably prevent back pressure and back-siphonage. The redundantly secure design of this device makes it suitable for protecting drinking water.

Tempering valves are generally used in residential homes for personal hygiene purposes, where water delivery is a maximum of 50°C (122°F)

Tempering valves are adjustable and temperature-activated, meaning they moderate hot water flow when necessary to ensure water isn’t too hot when it is delivered to a tap. Hot water that is stored in a hot water storage system should be kept at a temperature of at least 60°C, however, water should be delivered through a faucet at a maximum of 50°C. A tempering valve works by blending hot water with cold water so it flows through your tap at the correct temperature, within 3°C +/-.

These incidents of contamination typically happen in “cross-connections” or connections between two water systems wherein one is potable and the other isn’t. Here are some common examples of cross-connections in the home:

As implied by the name, a hose bib vacuum breaker is typically used for outdoor faucets where a hose connects. This threaded device can be screwed onto the faucet and prevents backflow with its single spring-loaded check valve. The valve opens and closes depending on the water pressure, thereby allowing water to flow only one way, preventing the back-siphonage of non-potable water (e.g. from a pool, puddle, bucket of soapy water) via the hose’s end.

Tempering valves are required to be installed in the following situations (in accordance with the Plumbing Code of Australia):

The atmospheric vacuum breaker or (AVB) is typically made of brass and is bent at a 90-degree angle. Inside an AVB, there is a poppet valve that is held up and out of the way by normal water pressure. In this state, air cannot enter. However, if the pressure is reduced and backflow is about to happen, the poppet valve is dropped and blocks the line. Along with this action, air is allowed into the system to break up any kind of back-siphonage.

A double check valve or double check assembly (DCA) is a device that has two spring-loaded check valves that are placed in a series. Since these two valves operate independently, one of the main advantages of having this backflow preventer is that even when one valve fails, the other can take over. Moreover, if both valves are functioning, the closure of the first valve reduces the pressure differential across the other valve, resulting in a tighter and more reliable seal against backflows. The most common application for DCAs is preventing backflow in fire sprinkler systems.

A tempering valve is a temperature-sensitive 2-inlet or 3-inlet mixing valve which pulls water from your hot water system, mixes it with cold water and delivers it to a faucet. General household use requires hot water to be no hotter than 60°C, however, appliances such as dishwashers and washing machines may have differing settings.

Under normal circumstances, wherein your plumbing system is in tip-top shape and your home or building is providing a steady supply of water, backflows don’t happen even without a backflow preventer. This is because the water pressure, by itself, would be flowing strong enough through your pipe network – thereby keeping water still or flowing in one direction.

If you need backflow preventers installed in your home/building or if you need to repair the backflow preventers that you currently have, then get in touch with a trusted plumber. At PlumbWize, we ensure quality service for all your plumbing needs. We make it a point to get the job done right the first time and give you reliable and long-lasting plumbing solutions.

However, incidents such as breaks in the main water line or when a fire hydrant is used can reduce the water pressure in your home or building. When water pressure is reduced or fails completely, water won’t be pushed forward into your home and fixtures – instead, it will flow backwards into the city lines. Thus, without a backflow preventer, contaminants such as fertilizers, chlorine, soap, and human waste can be siphoned back into the public drinking supply due to the negative pressure.

There are numerous types of backflow preventers with their own mechanisms and unique applications. Your plumber will be able to advise you on the best type for your home and what is required by your municipality. In this section, we will talk about the different kinds of backflow preventers, how they work, and where you can typically find them.

Because these devices work with atmospheric principles, they cannot be installed in an environment that has air contaminants that should not get into the water. Another limitation of this device is that the potable water line (the line that’s protected) needs to be upstream from the non-potable water source. The most common use for these kinds of valves is for irrigation systems.

Unlike other types of backflow preventers, an air gap is completely non-mechanical. For sinks and bathtubs, an air gap can be created just by putting the faucet high enough above the flood rim of the sink or tub. In situations that this can’t be done, an air gap device is used. Air gap devices are common for water softeners and dishwashers. The air gap, whether achieved through proper fixture placement or using a device, provides a physical break between the water source and the container of non-potable water.

A qualified plumber can install a tempering valve, however, a plumber with a TMV licence is the only one who can install a thermostatic mixing valve.

TMVs are generally used in environments that include high-risk persons, such as children, the elderly and the sick, that require a lower water delivery temperature (usually 45°C or 113°C as a maximum).

A TMV works by mixing hot and cold water together to achieve a particular temperature (within 1°C +/-) to be delivered in various. The temperature is usually preset by a plumber or a qualified tradesperson who has installed the device, and the element within a TMV that is sensitive to thermal activity automatically arranges the appropriate levels of hot/cold water to create the correct temperature of the liquid.

Backflow preventers are devices installed in the pipes of your home or building to ensure that water flows in one direction and never the opposite. These kinds of devices protect potable water supplies against contamination from various kinds of cross-connections, thereby keeping drinking water safe and clean for everyone. If you would like to learn more about the types of backflow preventers, how they work, and what they’re typically used for, then you’re in the right place!

A reduced pressure zone device (RZPD) is a device used specifically to prevent health hazards. RZPDs are equipped with two independently-action spring-loaded check valves. In between these two valves is a pressure-monitored chamber called the “zone.” The pressure in this zone is maintained by a differential pressure relief valve. This third valve will open to the atmosphere in the event that both check valves fail. The two independent valves can also take over for each other in case one of them fails – similar to how double check valves work.