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The Age of Continuous Flow Hot Water Heaters
Chofu
Noritz
Rinnai
Paloma
Takagi
Any of these brands ring a bell? One or two of these names you may have heard of, but the others most likely not. How can you make the best decision of which continuous flow hot water heater to choose if you are not aware of some of the available choices that exist on the market?
I will alleviate the amount of research you need to do when looking up about continuous flow hot water systems. This blog discusses all of the major manufacturers of continuous flow products and explains the advantages and disadvantages of each product. Thereby giving you the information to make an informed decision on which product best suits your needs. This unbiased perspective is coming from a licensed Plumber and Hot water specialist who has worked in Australia and the United Kingdom. The following information is based on years of experience and extensive work in the hot water market of installing and servicing continuous flow hot water systems.
*I am not promoting a specific product, but rather giving you information from what I have seen to help you to choose the right heater. At the end of the day, I just want you to enjoy your nice hot shower.
What are continuous flow hot water systems?
Also known as instantaneous hot water systems, continuous flow hot water systems are different from storage hot water heaters. With a continuous flow hot water heater you always have hot water (as the name implies) versus having the hot water stored in the tank which could run out during usage throughout the day. This graphic illustrates how the continuous system works to provide you with hot water when you turn on the tap.
For those of you who prefer audiovisual examples, here is a video from one of the first and still major continuous flow manufacturers, Rinnai. In the video Rinnai is promoting a new product, but it is also informative to see the benefits of a continuous flow heater.
History of the Continuous Flow Hot Water System and Why it is popular?
In 1991, continuous flow was introduced into the Australian market place from Japan by Rinnai. Now fast forward a bit and a lot has changed in the marketplace since having just the one major manufacturer. Today there are 4 major manufacturers with numerous small manufacturers.
What makes continuous so appealing? Not only do you get to always have hot water, but it is also efficient. You will see this prominently displayed on the front of the heater. The energy efficiency measurements range from 4 star up to 7 star gas efficiency. Additionally you may see some buzz words being advertised to make the product sound even better. One that you may come across is “condensing continuous flow”. All this means is that it uses exhaust gas as a preheat for the incoming cold water to increase the temperature. This in return further increases the efficiency of the heater to 6.7 to 7 stars.
Continuous flow is absolutely dominated by Japanese manufacturers with some smaller Chinese manufacturers coming into play. In Australia, we have not seen as of yet to much of the European manufacturers coming into market.
Below, in addition to telling you the good and the bad- I will also discuss where the continuous flow hot water system is from (manufactured) and at the end will summarize in a quick easy table for comparing the different products.
Well Established Manufactures in the Continuous Flow Hot Water System Market
Rinnai
Now that you have read through the intro you are into the meat of the story.. Do you remember who introduced the continuous flow hot water systems to Australia… correct it was the Japanese manufacturer Rinnai. Rinnai is the bench mark in both quality and reputation. Continuous Flow hot water systems do not get much better than this. Products offered include the condensing and non-condensing continuous flow. Rinnai is the name in continuous flow. I have just as many people asking for Rinnai units as I do for continuous flow.
While there
is a lot of good, some things do come up just like with any other product-nothing is perfect. There are a few issues with these units that I have fixed over the years. I have replaced a few printed circuit boards and cleaned the odd fan or combustion chamber out. Overall, the Rinnai continuous flow hot water systems are relatively maintenance free. I recently had the privilege of replacing a unit from 1992 that had not had an issue until it failed earlier this year. Now that is longevity of a product and reliability at its finest.
Rinnai has majority share for the Australian market. In Japan they are competing with Noritz for the top position.
Interested in finding more out about Rinnai continuous hot water systems or other Rinnai products? Check out their website.
Dux
Dux has had a few models of continuous flow hot water heaters over the years. These include the Du
x Deliverance, Dux Endurance Chofu style, and Dux Endurance Rinnai style. The Dux Endurance Rinnai style is actually a rebadged Rinnai B26. This will be elaborated on more further down.
The Dux Deliverance is an older model. It was a small part of their market and I tend not to see so much these days. I am unsure which manufacturer looked after this heater, but it was most likely Chofu or Takagi. I have not performed too much maintenance on these systems. This is due to Dux Deliverance getting on in age and parts were becoming more difficult to obtain as I came into the hot water industry.
Their second Continuous flow the “Dux Endurance” was a Chofu model. When Dux first brought these out they had the only “non-condensing” 6 star continuous flow. By doing this it helped with the upfront costs of these systems to the consumer. The Dux Endurance model finished selling around 2012. I have performed a lot of service work on the Dux Endurance model. This includes replacing multiple components with the Dux Endurance. The parts that I have replaced on this hot water system are printed circuit boards, water valves, proportional valves, and a fan. Most of the issues that occurred with these systems centred on issues with the printed circuit board and heaters not reaching desired temperatures. This temperature issue was overcome by the installation of a few resistors on the outlet thermister. Though I had to replace the printed circuit boards, this chofu model had reasonably cheap printed circuit boards compared to some other brands of continuous flow hot water heaters.
Currently Dux has moved onto their rebadged Rinnai heaters. These Dux hot water systems are apparently Rinnai’s previous series model- the Rinnai B26. In terms of service work on these Dux Endurance Rinnai style models, I have done very little. Mostly the issues I have come across are issues with the installation itself or gas pressures. What is difficult with this model is the price $$$. You have a B26 and Dux Endurance Chofu style which have the same warranty, same efficiency, same parts, but close to $200 difference in price.
The Future for Dux/Noritz
Dux were bought out by Noritz late last year. Up until now, there seems to not be a huge amount of change in the company. Currently it is a bit more of ‘a watch this space’, as many of the other hot water manufacturers are in limbo as to what Noritz is going to bring to the Australian market.
Noritz Tankless Water Heater
The rumour mill suggests that Noritz will bring out their own 6 starcontinuous flow products and leave other manufacturers with only access to their 5 star gas efficiency range. The future is looking bright with Dux/Noritz through the possible majority share of the market and their focus on improving their products through state of the art research and development. In recent years, they have gotten on board with Bunnings.
Keep up to date with the latest information about the Noritz continuous hot water systems. If you are interested-be sure to check in the next few months to see what continuous product they bring out.
Bosch
Bosch Highflow Series-17E, 21E, 26E
Bosch uses the Noritz brand for most of their continuous flow products which includes the 17E, 21E, and 26E and corresponding Bosch professional products. Bosch has recently brought out their 4000S range which is a room sealed internal range of continuous flow products. I believe this product range will come into its own because of the distinct advantages it offers. One of these advantages includes ease of installation in locations that cannot be installed by other heaters.
Are Bosch products made in Germany? Many people associating Robert Bosch hot water with the Germans would be wrong. Although Bosch itself is a German company, the Noritz product (which Bosch purchases) is rebadged and sold as Bosch continuous flow. Bosch’s new 4000S range is made in Portugal.
Bosch 4000S Internal
How do the 4000S continuous flow range products measure up? The product has not been out long enough for me to have an opinion. However, in terms of the existing continuous flow range, I do not find too much fault with it. It is a good price and a consistent product. Maintenance issues are mostly printed circuit board issues and filters becoming blocked fairly easily. I also came across an inbuilt circuit breaker tripping issue. However, this issue only occurred in Bosch continuous hot water system units that got to a certain age.
As I mentioned before the hot water industry in Australia is a bit in limbo with Dux being bought by Noritz. I believe Bosch hot water Australia would be the company most in limbo. On the flip side I would not underestimate what Bosch may bring out in response as a competitive product.
Want to learn more about the Bosch Continuous Hot Water System Range? Check out the Bosch 4000S Internal Continuous Flow Heaters and Bosch Highflow Series brochures.
Paloma/Rheem
AKA Aquamax, Edwards, Solahart, Vulcan, Everhot and Rheem Continuous Flow
The Rheem continuous flow is owned by the large Japanese corporation Paloma. Worldwide, Paloma is a very dominant hot water company. Their continuous flow heaters do have a tendency to have issues with printed circuit boards. The major downside of this is the cost. Most of their printed circuit boards will set you back $700 to $900. They have changed things with being the only continuous flow on the market that delivers 27 litres per minute. This highest capacitive on the market benefits the customer because multiple hot water outlets can be running simultaneously and you do not lose pressure or the hot temperature of the water.
AquaMax Continuous Flow Heater
Rheem 27L Continuous Flow
Everhot 20L Continuous Flow Heater
Vulcan Continuous Flow
Emerging Manufactures in the Continuous Flow Hot Water System Market
Chromagen
Chromagen Eternity Continuous Flow
Chromagen is an Israeli company which has been established in Australia for some time now. Chromagen is branding their continuous flow as an eternity (they are implying that you never run out of hot water-it lasts for an ‘eternity’). Also, the Eternity continuous flow hot water system is sold through Bunnings. If you have been to Bunnings and looked at the selection of hot water systems, the Chromagen Eternity is the cheaper continuous flow that they sell.
In terms of servicing the Eternity Chofu continuous flow, it was very easy to service because of my previous history with the Dux Chofu product. However, they have since changed over to the Takagi brand continuous flow that is also out of Japan. My experience with servicing the Takagi models is not as great as some other manufacturers. However, I have replaced a few printed circuit boards in these products.
This brochure has information about the Chromagen Eternity Continuous Flow including technical information.
Thermann
Thermann 6 star Continuous Flow
Thermann 5 star Continuous Flow
Reece have been badging their own continuous flow for some time now. Reece is using the Chofu system. I am unsure if Chofu have sorted out printed circuit board issues they were having with their previous models. For the sake of Reece’s reputation I hope they have sorted out these issues. With Reece’s 200,000 + hot water heaters, they have taken a large percentage of the hot water continuous flow market and are increasing this market everyday. Thermann is the main and biggest user of the manufactured Chofu brand.
ThermaStar
I have only dealt with this product from an installation perspective. In my opinion, I believe that it is at the lower end of the market. They use ½ inch cold and hot.
Kelvinator/Leda
Kelvinator Continuous Flow
Leda Continuous Flow
Absolutely everyone has their own continuous flow these days!
Kelvinator has also hopped on the continuous flow bandwagon a few years ago. This Swedish company owns the American brand Kelvinator. Kelvinator has mostly sold direct to some builders. I believe this unit is a Takagi. I have not been called out to one of these products as of yet, so cannot confirm this. My opinion on this is that I would probably stay away from this product until there is a little more market confidence.
Kelvinator Continuous Flow Brochure
So know you know all about Continuous Flow Heaters
As you can see it is the Age of the Continuous Flow hot water systems. Many companies are selling this product, but when it comes down to it, there are a few Japanese models- mainly Chofu and Takagi-that are being sold. This may make you think a little more because though there is a good reputation behind the company- where is the heater REALLY coming from. Just one more factor to consider when choosing which continuous hot water heater is best for you. Good luck in your continuous flow hot water heater search and I hope you learned something new from this information. Also one last thing to mention- Warranty information. All heaters have a 10 year heat exchanger warranty and 3 years parts & labour. Exceptions: Rinnai offers 12 year heat exchanger warranty. Merlin only has a five year parts and labour warranty.
Continuous Flow Hot Water Systems Highlights
Well the inner workings of hot water systems are made to heat up the water- right? Yes, but there is point where it can be too much and actually damage your heater.
Why is it bad for your hot water heater to overheat?
Waters at high temperatures are potentially dangerous as hot water obviously burns, but can also be dangerous to your hot water heater. If the hot water boils over or even over heats more than what is recommended in your cylinder it can dramatically reduce the life expectancy of your hot water heater.
It reduces the life span by creating tiny cracks in the vitreous enamel lining on the inside of the tank, with prolonged over heating these cracks will become worse and worse. Once the vitreous enamel has been eaten away over time the water will then start to eat at the steel tank cylinder.
Safeguards to stop this
For electric hot water heaters the primary form of protection is an ECO or energy cut out. Inbuilt into the thermostat of the hot water heater is a temperature disc. This temperature disc discharges at setting of around 85 degrees depending on the type and brand of thermostat. (The most common brands of thermostat in the market place are the Klixon and Robertshaw) When this energy cut out activates it de-energises the element to stop the water heater from heating any more. At this stage you would soon have no hot water and need to phone a technician at Same Day Hot Water.
For gas hot water heaters, the unitrol works as their primary form of over temperature protection. At temperatures ranging between 70 and 85 degrees (depending on the brand and type of controller the most common in the market place being Robertshaw and Eurosit) the ECO will activate cutting the gas off. At this stage you can make a phone call to us here at Same Day Hot Water for us to get you back in hot water!
The secondary for of over temperature protection is done through the pressure temperature relief valve. The relief valve usually has a setting between 95 and 99 degrees before it fail safes and dumps water to cool down the tank. It does this through a wax element inside the valve detecting temperature high temperature and opening up.
What is an anode? How does it work?
What is an anode and why is it so important?
Water heaters have anodes in them to protect them against rust.
All mains pressure, storage water heaters, other than those made from stainless steel, are constructed from 2 to 3 mm thick mild steel which has been coated on the inside with vitreous enamel similar to that which is used to rust-proof barbeques. They are never made from glass or fibreglass. Any misunderstanding here stems from the industry term “glass-lined which is commonly used to describe this type of tank.
This enamel coating is subject to extremes of temperature and pressure which causes it to deteriorate over time. Therefore, all glass-lined tanks are also fitted with one or more sacrificial anodes to protect the steel tank against corrosion as the glass lining loses its effectiveness. Even in places like Sydney and Melbourne, where the water quality is quite good, (TDS*) readings of less than 100 parts per million) anodes in small water heaters can last for as little as 4 or 5 years before being expended and thus allowing corrosion to commence. NB: Refer to the section – “How long should an anode last before it needs replacement” to see how long an anode should last for each size of heater.
(*Total Dissolved Solids)
By simply replacing a heater’s anode when required, (the period varies depending on the size and model of the heater) the same protection is provided that keeps ships afloat, underground steel pipelines and tanks corrosion free and even Australia’s and the World’s sea-based oil drilling platforms intact. – That’s why the heater manufacturer put the anode there in the first place.
How can corrosion take place in an enclosed tank full of water?
Corrosion in water heaters is associated with the passage of minute electrical currents which travel through the metal and the water. Corrosion takes place at the anodic areas (the anode) which are the places where the current releases ions to dissolve in the water. Cathodic areas develop at other sites (the tank walls) where the circuit is completed and at these places, provided there is an effective anode working inside the tank, no corrosion can, or will, take place. Anodes corrode – cathodes do not. Once the original anode stops working, the steel tank will react with other incompatible metals such as the copper pipes, brass fittings and the element/s. Once this occurs, the tank wall becomes anodic and corrosion (rust) commences and the tank will very quickly rust through.
How do anodes work?
Anodes are manufactured from a special grade of magnesium and they protect steel by a sacrificial electrochemical action. Magnesium is electro-negative relative to steel. When a magnesium rod is fitted to a steel tank filled with fresh water, a current will constantly flow through the water between the rod and any exposed steel area on the tank wall. The circuit is completed through the tank back to the magnesium rod. This protective current is produced by the magnesium releasing ions, and this results in corrosion in the anodic area. The magnesium (the anode) corrodes instead of the steel tank (the cathode). This principle of electrolytic corrosion control is called cathodic protection. Because cathodic surfaces cannot rust, the steel tank is protected.
This principle is nothing new. No experienced boat owner would risk the propeller, rudder, shafts or other exposed metal equipment on his boat, when all it requires to ensure that they do not corrode, is to keep an effective sacrificial anode in place on the hull of the craft or on the motor itself in the case of outboards. The same system is used on all commercial shipping, oil drilling platforms as well as underground pipelines and storage tanks. It’s far more economical to replace the anode than to allow the vessel itself to corrode. This logic also applies to domestic and commercial water heaters.
Anodes and Hot Water System Types
All gas, electric and solar mains-pressure water heaters with a vitreous enamel or bonded ceramic coating utilize a sacrificial anode to provide additional corrosion protection.
The common brands are Rheem, Vulcan and Dux as well as Solahart solar heaters.
Which heaters do NOT have an anode?
- Gravity Fed Tanks located in the ceiling.
These are mostly found in older homes and they are rarely supplied new nowadays due to the fact that the hot water supply relies on gravity alone and as such, it is not very satisfactory for showering.
- All types of Continuous (Tankless) Gas Heaters.
These are small, wall-mounted heaters which heat the water as it passes through them. Common brands are RINNAI Infinity, Rheem Integrity, Dux Endurance as well as Bosch, Pyrox, Zip, etc.
- Stainless Steel and Copper Storage Type Heaters.
These heaters look similar to the ones that do require an anode. They are generally the same size and shape but the tank is either stainless steel or copper and does not require an anode.
Brand names with a stainless steel tank are Aquamax gas heaters and Edwards, as well as some models of Beasley, in both electric and solar types. Copper tanks haven’t been produced for many years, but there are no doubt some still surviving because they have been known to last for 40 years or more. They don’t ever have anodes in them.
What about older heaters?
The older a heater is, the greater the likelihood of it having little or no remaining active anode and at the same time, having experienced an appreciable deterioration of the “glass” lining, thus leaving areas of exposed steel wall where corrosion may have already started. While that corrosion cannot be reversed, it can certainly be arrested by the introduction of a new anode, which can get to work by reversing the electrical flow and converting the tank wall back to a cathode (parts of it will have become anodic after the original anode ceased operating).
Replacing Anodes
When to Change the Anode
Anodes are manufactured by extruding the magnesium alloy onto a central core of 3mm diameter mild steel. Where an anode is active and working effectively, it will appear sharply pitted and the “valleys” of this pitting will be grey in colour the same as the original magnesium. As the anode corrodes, it will wear down to the core and then progressively expose the core, usually from the top down. Ideally, the anode should be replaced before it has worn down to the core in order that there is sufficient surface area of magnesium to provide adequate corrosion protection.
As many as 50% of anodes become inactive, or passivated, and in these cases, the anode is not sharply pitted as above, but appears smoother and will be partially or fully coated with calcium carbonate, usually brown in colour or sometimes white. These anodes can be quite thick and appear to have sufficient magnesium left, but because it is heavily coated it is providing little or no effective protection to the tank and such anodes should be replaced.
Our experience tells us that, the longer and/or the thicker the anode, the longer its life. Nevertheless, all heater manufacturers are very definite in recommending that anodes should be replaced in order to ensure maximum effective life of their heaters.
Suggested Replacement Times of Hot Water System Anodes
| Original Anode* | 2nd Anode* | |
|---|---|---|
| Dux 50 & 80 litre electric | 5 years | 2-3 years |
| Rheem & Vulcan 50 & 80 litre electric | 6 years | 3-4 years |
| Rheem & Vulcan 125 and 160 litre electric | 7 years | 3-4 years |
| Rheem & Vulcan 250 litre electric | 8 years | 4-5 years |
| Dux 250 litre electric | 6 years | 3-4 years |
| Rheem & Vulcan 315 & 400 litre electric | 8 years | 4-5 years |
| Dux 315 & 400 litre electric | 7 years | 3-5 years |
| Rheem 90 litre gas | 7 years | 4-5 years |
| Rheem & Vulcan 120, 135 & 145 litre gas | 8 years | 4-5 years |
| Rheem & Vulcan 170 & 185 litre gas | 8 years | 4-5 years |
| Rheem 200, 260 & 290 litre twin anode gas | 9 years | 5-6 years |
| SOLARHART 300 litre | 10 years | 7-8 years |
| OPTIMA 135 & 170 litre twin anode gas | 10 years | 6-8 years |
| OPTIMA 200 & 260 litre twin anode gas | 10 years | 6-8 years |
| OPTIMA 250, 315 & 400 litre electric | 10 years | 6-8 years |
*These suggested replacement times of the original anode must be used only as a guide.
The life of an anode is dependent upon a number of variables:
- Water Quality
Natural waters contain a wide variety of dissolved salts, all of which act as carriers of electric current. The higher the salt content of the water, the lower its electrical resistance and the greater the corrosion potential. Artificially softened waters are exceedingly corrosive, because the process merely substitutes a sodium ion for the magnesium and calcium ions and this takes away all of the scale forming ability, but does nothing to reduce electrical conductivity.
- Size of Household
Hot water storage tanks are under constant pressure, so each time a hot water tap is turned on or off, the tank expands and contracts. Washing machine solenoid valves and ceramic mixer taps turn on and off more sharply than screw-type tap mechanisms which results in fast pressure changes inside the tank. These changes in pressure cause the glass lining of the tank to crack thereby exposing the steel of the tank to the effects of corrosion.
- Method of Heating
Anodes in gas storage heaters usually last longer than those in electric tanks because gas heaters are typically operated at a lower temperature than electric heaters and having no copper element in the water means that there is less corrosion of the anode resulting from electrolysis.
- Temperature Setting
Hot water is more corrosive than cold water, so the anode is consumed more quickly when the thermostat is set higher than necessary. It obviously consumes more heating energy as well. This point partially explains why anodes tend to wear more quickly at the top than elsewhere.
When is it too Late to Replace the Anode?
Most heaters should last around 12 to 15 years. There are always exceptions and we have seen heaters 20 or more years of age which are still providing good, clean hot water. On the other hand, we have also seen a few heaters which have rusted through as early as five years of age. Obviously both are extreme examples. Experience has shown us that, once rust gets started, it takes about three years for it to eat right through the tank wall. Therefore, the average heater only starts to rust at the 10 to 12 year mark.
For this reason, we believe 12 years should be the limit for replacing anodes in standard model heaters. Again, exceptions can be made when the heater looks in good condition and where the anode is still working. (That is when grey metal is clearly visible, indicating that anodic reaction is still taking place.) If water quality is tested and there is no discolouration, we see no reason why the anode should not be replaced. This is particularly applicable to Rheem Optima® models which have a heavy duty anode in electric heaters and twin anodes in gas models as well as having a heavier coating of vitreous enamel. However, take special care with the twin element electric tanks as we have seen some of these models fail within the ten year guarantee period.
Extract from Rheem Owner’s Guide
About your Water Heater
How long will the water heater last?
There are a number of factors that will affect the length of service the water heater will provide. These include the water quality, the water pressure and temperature (inlet and outlet) and the water usage pattern. However, your Rheem water heater is supported by a comprehensive warranty.
Anode Protection
An anode is installed in your water heater and will slowly dissipate whilst protecting the cylinder. The life of the water heater cylinder will be extended by arranging for an authorised person to inspect the anode and replace it if required.
The suggested time after installation when the anode should be inspected is:
| Rheemglas® | 8 years |
|---|---|
| Optima® | 10 years |
For softened water supplies or in areas of bad water quality, it is recommended the anode be inspected 3 years earlier than shown.
Extract from Dux Water Heaters Owner’s Handout
Five Year Service
(By Authorised Personnel Only)
The five yearly service should be carried out by an Authorised Person. It is recommended that this service be carried out by your local Dux agent or qualified Dux technician. The service should include the following:
- Replace the pressure & temperature relief valve.
- Replace the anode.
- Clean and service the gas burner and pilot on gas models.
- Flush the cylinder.
Hot Water Systems generally last around 8-10 years give or take. Did you ever wonder how to tell the age of your hot water heater?
Most water heaters have an identifying sticker, or label, detailing the heater’s capacity, model and serial numbers plus details relating to its operation. This sticker will show the date of manufacture of the heater and a close estimate of when it was installed will be two or three months after this date.
In the market for a new hot water system? Looking to replace your existing hot water system? Hot water systems are available in many different capacities. Some criteria may be obvious, but here is a helpful list of factors to consider when choosing the right hot water system for you.
- Number of people/bathrooms
- How many bathroom or people will be using the hot water at once?
- Age
- How many adults, how many children?
- Keep in mind teenagers have high hot water usage. Young children have low hot water usage.
- Appliances using hot water at the same time
- Dishwasher and washing machine; A mains pressure hot water system is able to maintain pressure when multiple taps are being used simultaneously
- Baths
- Will a large amount of hot water be needed to fill a bathtub or spa-bath
- Climate where you live
- Type of fuel available
- What type of fuel do you have at your house? Natural gas, liquefied petroleum gas, or both?
- Space
- Do you have room for the unit inside the house, outside, or only a small compact space that would fit an under bench hot water system
- Budget
- Looking at environmentally friendly options?
- Solar hot water systems and heat pumps utilize the sun to produce hot water
- How many adults, how many children?
This is the technology that utilizes the principle that hot water rises. As you can see in this picture water moves according to temperature differences within the system. As the water heats up it becomes less dense which causes it to rise up through the collector. There is no need for pumps or controllers as the storage tank is installed above the collector allowing the hot water to flow into the tank.
There are so many hot water systems available on the market today. While it is nice to have so many options, there may be one factor in particular that is of interest for you that will help you decide which hot water system best suits your needs. One of the top factors would most likely be running costs. The New South Wales Government Office of Environment compiled a helpful comparative table regarding the running costs of heaters based on different factors. Hyperlink
This is something important for you to know about hot water systems. If you had your hot water heater installed prior to 2013 this may be more pertinent for you.
By law, the minimum required temperature within a hot water heater needs to be above 55 degrees Celsius to prevent the growth of legionella bacteria.
However, this is too hot for general household use so a tempering valve is needed to lower the temperature of the water.
AS NZS 3500.1:2003 Plumbing and Drainage, Part 4 Heated Water Services Plumbing Code of Australia 2013 Part B2
