Every week we have clients asking why we are required to install a TMV or tempering valve to their hot water system. The short, simple answer is because it’s the law.
The longer answer is because it’s about safety. A TMV or tempering valve reduces the risk of scalding. This is because storage type gas, electric, solar and heat pump systems are storing hot water at between 60° C and 75° C. You need to be aware a severe hot water burn can occur in one second when the water is delivered at 60° C or higher. Hot water burns like fire because:
- At 60°C, a severe burn can happen in 1 second
- At 55°C, a severe burn would take 10 seconds
- At 50°C, a severe burn would happen after 5 minutes
What is a TMV?
TMV or thermostatic mixing valve installed by Whywait Plumbing
A TMV is a thermostatic mixing valve but is commonly referred to as a TMV. The role of a TMV is to mix hot and cold water together to provide you with hot water delivery at your tap that is at a consistent temperature.
When we install your TMV, we set the temperature to deliver the hot water in all bathrooms at 45°C in aged care or childcare facilities or 50°C in all other bathrooms.
A TMV is compulsory for use when used in common areas for aged care or childcare. A TMV is very accurate and very responsive to fluctuations in incoming water temperatures keeping the temperature to within 1° C of the temperature that it has been set at when we install it.
Accuracy of temperature in the TMV is delivered by a thermally sensitive element which expands and contracts in response to the temperature fluctuations of the incoming cold and hot water. This expansion and contraction regulate the temperature by controlling how much cold water mixes with the hot water. An added safety feature of a TMV is that if cold water flows become too low, they shut down to prevent 60°C plus water being delivered.
What is a Tempering Valve?
Non-compliant tempering valve installation connected with flexihoses replaced by Whywait Plumbing
A tempering valve’s role is also to mix hot and cold water together to provide you with hot water delivery at your tap that is at a consistent temperature.
The tempering valve is a simple three-way valve that is temperature actuated to mix the hot and cold water. These days most come preset at 50°C and when we install them, we test them by measuring the temperature of the water from your hot taps in the bathroom.
A tempering valve is commonly used in residential homes as a one-off valve at the hot water service. A tempering valve is slower to respond to temperature fluctuations compared to a TMV plus it will deliver water to within 3°C of the temperature that it has been set at when we install it.
Which Valve do you Require?
The Plumbing Code of Australia in AS/NZS 3500.4:2018 is very specific about water temperature is section 1.11, which states:
- To avoid the likelihood of legionella bacteria growth, an installation shall store water at a temperature of not less than 60°C
- All new heated water installations shall deliver heated water not exceeding 45°C for the aged, the sick, children or people with disabilities in healthcare, aged care, early childhood, schools and nursing homes. For all other situations, heated water shall be delivered not exceeding 50°C.
Ultimately when we are installing a temperature control device, we are legally obliged to comply with the requirements above and much more as they are prescribed in AS/NZS 3500.4:2018.
Overall a TMV is more expensive to install initially compared to a tempering valve. However, a TMV has a much longer working life span compared to a tempering valve as they are more accessible to service and replace the working parts. A tempering valve, by comparison, is usually just replaced when it stops working as they are not easy to service or replace parts in.
In Queensland, all work undertaken on a TMV or tempering valve is reportable to the QBCC and must have a compliant Form 4 submitted. For your protection always demand a copy of your Form 4.
Do you have mould around the tiles or on the walls in your bathroom or kitchen? If you do then you are not alone as it is a common problem particularly in bathrooms but also in kitchens in South East Queensland due to our sub-tropical climate. Like most problems prevention is vital and often very simple.
Because your bathroom and especially the shower area are the wettest areas in your home it is not uncommon to see mould growing in the grouting and silicon sealants. Bathroom Mould loves the perfect atmosphere to create the ideal conditions for mould growth in the cracks and gaps in the tiling. Consequently mould grows in behind and through the grout joints on the tiles. As can be seen on the photo on the right mould loves getting in behind the silicon seal on the internal corners whether it be the wall or the floor.
The most common area to find mould is in your shower where it is nourished by your body oils, shampoo and soap residue that are left behind every time the shower is used.
Poor air circulation actively assists mould growth as the warmth and moisture created in the enclosed area of a shower offer further ideal conditions for mould growth in the dark areas of the shower around the internal corners and the shower floor drain. Poor air circulation is easily resolved by ensuring you install a good quality bathroom extraction fan above the shower that turns on automatically to remove all of the steam and water particles while you are using the shower.
If you are suffering from mould growth in your bathroom and or kitchen then Whywait Plumbing recommend that you act now to remove it before permanent stains are created. To not only prevent but also treat mould you need to use what nature uses and that is enzymes rather than corrosive chemicals. Enzymes are a natural part of our world and play an important role in everyday life. They are found in every living organism and life is not possible without enzymes. Enzymes are catalysts – not living organisms.
The success Whywait Plumbing have enjoyed with utilising Enzyme Wizard products is incredible with every problem we have utilised it on exceeding not only our expectations but those of our clients. Enzyme Wizard products are a guaranteed supply of plant based enzymes and enzyme products that by their very nature eliminate odours and organic matter, from blood stains, to cleaning carpets and counter tops, removing wallpaper, and even used as a high quality cleaner/degreaser.
For preventing and treating bathroom mould in the bathroom or the kitchen you need to utilise Kitchen & Bathroom Mould & Mildew spray which is a spray and wipe product which is suitable for all surfaces in a bathroom or kitchen whether they are formica or stone bench tops, tiles, glass, timber or stainless steel as it will not only attack existing mould but prevent mould developing.
If you have surface mould in areas such as tiles grout simply spray the effected area with Mould & Mildew spray whilst cleaning the area with a stiff brush. Once you have finished brushing the area leave it 5 minutes then rinse it with clean water. If you have heavy infiltration of mould it maybe necessary to apply a couple of extra times to completely remove the mould.
Frequently you will find mould behind the silicon sealant on the internal corners in tile areas which will require more thorough work. You will need to use a utility knife such as a Stanley knife to scrape off all of the silicon plus ensure you use use a blade to scrape the remnants of silicon clear off the tiles. Once all of the silicon has been removed spray the mould with Mould & Mildew spray as above until it has all disappeared. Once the mould has gone rinse the area clean and dry it thoroughly with a hot air dryer to ensure there is no moisture trapped in the open joint. Finally you will need yo apply a good quality mould resistant silicon to the joint which is specifically designed for high moisture areas.
Once you have removed the kitchen or bathroom mould you need to ensure that you remove the chemical cleaners and bleaches from your cleaning regime and use Enzyme Wizard products in your bathroom and kitchen to prevent mould reoccurring and ensure you have a positive prevention program in place in your home that contain no harmful phosphates or caustic chemicals.
If you observe mould reappearing after a few days of removing then you may have problems with leaking pipes or fittings that require a thorough investigation by Whywait Plumbing to ensure you are not damaging internal frames and wall linings. If you have leaking pipes or fittings behind the wall then mould is only a sympton of a bigger problem and ignoring will not make it disappear. If in any doubt contact Whywait Plumbing for advice on how to deal with mould in your bathroom and or kitchen.
Cloudy, hot water looks yuck.
Why is my hot water cloudy is one of those perennial questions that arise for the plumbing technicians at Whywait Plumbing?
Generally, the problem is based around reoccurring issues of, “what do you think causes cloudy (white not dirty) water that comes out of the kitchen tap when on hot. It doesn’t do it on cold, and if you boil cold, you don’t get the same residue. The photo attached is the residue after 30 seconds when the water settles.”
Very simply in most cases, cloudy, hot water is caused by dissolved gases in the water. We assure you it is safe to use.
To get cloudy water from your hot tap, you have to create the right set of circumstances for everything to come together at the same time.
So why is my hot water cloudy?
To explain this a little more, you have to understand that all your water is stored in your water pipes under pressure. Therefore water under pressure has a higher capacity to hold dissolved gases. When water under pressure is heated the ability to hold those dissolved gases is reduced.
Primarily what happens then that is your cold water is heated in a water heater it creates hot water under pressure. This results in supersaturation occurring with dissolved gases. Ultimately those gases are released when you turn on the hot kitchen tap.
Another way to look at it is that when you turn the hot tap on you create that same kind of effect as when you pop the cork off a bottle of champagne because all that pressure has to go somewhere.
Why hot water is cloudy when you first turn on a tap?
The reason your water is milky or cloudy when you first turn the water tap on is that turning on the tap releases the pressure. This pressure release is often an initial highly pressurised burst. Because the dissolved gas comes out of the water in the form of tiny gas bubbles right throughout the water filling a glass or container. The gas bubbles then rise to the surface of the water and burst so that the water has a cloudy or milky appearance.
The cloudy, hot water will clear in a few seconds. As it is gas bubbles dissolving the water will clear from the bottom up. You can easily observe in a glass the water rapidly clearing from the bottom up.
The good news is that dissolved gas or air in water in reasonable quantities is not uncommon and means that the water is in a “healthy” condition.
We guarantee cloudy water does not mean you have defective hot water service or your water is contaminated. Generally, gas bubbles in your hot water supply will increase with the increase in temperature of your water because of the hotter your water, the lower the number of gas bubbles that can be held.
What should I do if my hot water is always cloudy?
If after the initial burst of hot water, your water is continually cloudy then it needs further investigation. Gas bubbles do not cause the cloudiness that does not dissolve in hot water.
Seldom is it a fault with your hot water service. If the water does not lose the cloudiness within thirty seconds, you likely have a water filtration problem or a sediment buildup in the hot water tank.
Investigating cloudy, hot water needs to be undertaken by a licensed plumber so if you are continuously asking yourself why is my hot water cloudy you need to call us at Whywait Plumbing on (07) 5580 4311 and book a site visit.
The recent outbreaks of hot water Legionella in Queensland mainly in hospitals is of concern. These, for the most part, were warm water systems which are not the same as your home hot water storage tank.
With hot or warm water systems there is always some risk but every system checked in recent weeks by Whywait Plumbing has had hot water temperatures that virtually eliminate all risk. However, there is almost no risk of you or your family contracting Legionella bacteria as a result of it breeding in your home hot water system.
Legionella Transmission Via Hot Water
Legionella transmission is airborne via respiratory droplets containing the bacteria. Warm water and domestic hot water systems that are contaminated will generally see the transmission of the bacteria in a shower that has not been used for a period of time.
Hot Water Preventative Measures For Legionella
Hot water systems should be maintained so that water at the point of use at any tap or outlet is 50°C or more after having been turned on for one minute.
Hot water systems should not be used until they have reached 50°C especially if they have been turned on for any period.
Generally, domestic hot water systems should have a temperature of 60°C or higher in water leaving the hot water storage tank.
DO NOT turn down the thermostat on an electric hot water storage tank to below 60C.
Hot Water Temperature For Preventative Of Legionella
Hot water systems should be maintained so that water at the point of use at any tap has a temperature that affects the survival of Legionella as follows:
- Above 70 °C – Legionella dies almost instantly
- At 60 °C – 90% die in 2 minutes
- At 50 °C – 90% die in 80-124 minutes, depending on strain
- 48 to 50 °C – Can survive but do not multiply
- 32 to 42 °C – Ideal growth range
- 25 to 45 °C – Growth range
- Below 20 °C – Can survive but are dormant, even below freezing
What Is Legionella Bacteria or Legionnaires Disease
What it is:
- Caused by the Legionella bacteria, commonly found in creeks, ponds and soil.
- Rare in people under 20 years, with those over 50 years old who smoke or have a weak immune system particularly susceptible.
- Non-specific flu-like symptoms including fever, headache and muscle aches, developing within a week of breathing in the bacteria.
- Usually progresses rapidly with pneumonia symptoms, high fever, shortness of breath and chest pain typical.
- A person with the disease usually needs to be admitted to hospital for antibiotic treatment and care.
- Early diagnosis and antibiotic treatment important, and those treated usually begin to improve with three to five days.
Testing Your Storage Tank
For most homes, there is a very little risk of you having hot water legionella occur in your hot water storage tank unless you do really stupid things such as turn off your heating source.
An easy test of the storage temperature is to get a thermometer and test the temperature of your water from the overflow relief valve drain.
If you have any doubts about the temperature in your storage tank contact Whywait Plumbing to organise a service call to check your hot water system.
Judging by the number of phone calls in the last few days to Whywait Plumbing there is genuine concern amongst our clients over the threats posed to them from Legionella risk in their domestic hot water systems.
We can assure you whilst there is always some Legionella risk, there is almost no risk of you or your family contracting Legionella bacteria as a result of it breeding in your home hot water system.
The outbreak of Legionella bacteria in the hot water system at Wesley Hospital that killed a 60-year-old cancer patient and left a 46-year-old woman seriously ill has minor ramifications to be sure because all hot water systems can pose a risk.
That potential risk is why Whywait Plumbing is constantly advocating appropriate maintenance on your home hot water system to minimise that risk even further.
However, there is a huge difference between your home or domestic hot water system and the warm water recirculating system at Wesley Hospital. The Legionella outbreak in their warm water system has not been as a result of contamination in the hot water storage system or the hot water pipes but appears to be literally at the point of delivery from the shower where the water is cooler.
A warm water system is vastly different to your home hot water system with Wesley’s water temperature set between 42.5°C and 43°C. This is lower than the maximum 45°C legislated in the Plumbing and Drainage Act for hospitals. This low-temperature setting is a result of guidelines from Queensland Health that dictate hot water temperatures in hospitals be reduced to avoid the possibility of serious burns to young children and elderly patients. The downside of this requirement is that the possibility of Legionella bacteria surviving in reticulation pipes is increased. Water temperatures of around 46°C will kill legionella bacteria.
Warm water systems are typically found in care facilities, such as nursing homes, hospitals and child care centres, where water for purposes such as bathing and cleaning is provided at approximately 45°C to prevent scalding.
Your home hot water system if it is a storage tank is heating the hot water to between 60°C and 70°C. If you have a tempering valve or thermostatic mixing valve (TMV) installed then that has been set to deliver hot water at 50°C at each individual tap.
If you have no tempering valve installed, you virtually have eliminated all risk. But you have increased the risk of someone suffering a scalding from hot water. As always it is about managing risk.
However, there is an urban myth prevalent that you can reduce electricity costs by turning the thermostat down on an electric storage unit to 50°C. This is not recommended for many reasons but it will not save you electricity and to physically get a thermostat down that low requires physically breaking the locking mechanism on it that allows the setting to be between 60°C – 70°C. If you want to lower the delivery temperature the only acceptable and compliant method is to install a tempering valve.
In 99.99% of cases, the temperature ranges your hot water system operates in is almost certainly killing any Legionella bacteria. The risk if any, is after the storage tank in the reticulation pipes. By turning your shower on and running the tap with hot water first then cooling down with cold water to your desired shower temperature you are virtually eliminating what risk there is.
What the outbreak at Wesley Hospital has confirmed is that there is a risk from warm water and that maintenance of your hot water systems will manage and eliminate that risk.
What Whywait Plumbing do recommend is that you take advantage of our ongoing reminders and offers to service your tempering valves. This not only ensures that water is being delivered at 50°C but eliminates any possibility of Legionella. It also ensures you are complying with the requirements of most insurance policies in ensuring that routine maintenance is undertaken plus we provide you with a written report and a form 4 compliance certificate that is further evidence of your hot water unit being compliant.