Technical Information

Colour code: Orange for average to hard water areas
Blue for extremely hard water areas

Electric

Dux Models Litres Anode Length (mm) Orange Anode
Part Number
Blue Anode
Part Number
80T1 80 686 H0857 H8867
125T1 125 805 H0854 H8864
160T1 160 1090 H0858 H8868
250T1 250 1150 H0855 H8865
315T1/T2 315 1440 H0851 H8861
400T1/T2 400 1370 H0856 H8869

Gas

Dux Model Litres Anode Length (mm) Orange Anode
Part Number
Blue Anode
Part Number
135 ALL MODELS 135 1090 H0849 H8859
170L ALL MODELS 170 1440 H0845 H8855
WL = WATTS
60 x 1.63 x â–³T

 

Where WL = Water in litres/min
  â–³T = Difference between the outgoing water temperature and the incoming water temperature.
1 Gallon 4.54 litres    
1 kg 1000cc 0.22 gals 1.76 pints
1 kW hr 3412 BTU    
1 kWh 3.6MJ    
1 kPa 0.145 psi    
1.163 Watts Watt hours is the amount of energy required to raise 1 litre of water through 1 degree c

"Children under five have a one in two hundred chance of being hospitalised because of scalding by hot water in the home.

It is in response to this frightening statistic that the AS3500.4:2003 Heated Water Services (Part1.9.3) was implemented.

The apparent conflict regarding storage and outlet delivery temperatures between AS 1056 and AS 3500.4.(Part 1.9.1) requirements can be resolved by installation of temperature control devices which include thermostatic mixing valves, tempering valves, end-of-line devices.

These devices and the "correct" method of installing them in order to meet the code has been a source of much confusion and frustration lately but "problems are opportunities". The important point to remember when confronted by this opportunity is that AS3500.4 has been written as a performance based standard and hence it provides the opportunity for many and varied methods of compliance - this includes freedom in positioning the temperature control devices and the layout and sizing of piping.

That is, the scope for more creative plumbing configurations on water heater installations allows the plumber willing to do their homework to both meet the requirements of the code and provide an even more flexible hot water system installation than ever before.

In preparing your approach to your next hot water installation don't forget that all Dux Electric Storage and 5-star Gas storage water heaters have dual inlets and outlets providing flexibility of installation positioning in tight and unusual positions. They also have the facility for dual outlets; one supplying hot water to temperature control devices for supplying personal hygiene areas and the other to areas such as the kitchen and laundry where piping hot water above 50°C is needed. In your efforts to provide a flexible and high performance hot water reticulation system using this feature don't forget the issues of flow volumes and velocities when sizing pipework! Please note 4-star Gas Storage is left-handed only, with a single inlet and outlet on the left hand side of the heater.

For further information contact Dux on 1300 365 115.

In keeping with Australian Standard AS3500.4, the terminology CWRV (Cold Water Relief Valve) has been changed and is now described as an ECV Expansion Control Valve). In short, there is no difference between an ECV and a CWRV.

Definition
The term ECV is used to indicate that the valve is intended to cope only with the excess pressure generated as the water expands during a normal heating cycle.

Purpose
An ECV limits the maximum pressure in a water heater by relieving excess pressure to the drain. As the ECV is fitted to the inlet line of a water heater, the discharged water is cold. The cold condition prevents the depositing of calcium carbonate that would occur if this discharge was through the PTR valve.

When to Use an ECV

  • An ECV is fitted when the water supply has a tendency for form scale. This type of water is referred to as scaling water because calcium carbonate is deposited out of the water onto any hot metallic surface. If scaling could occur as water passes through the PTR valve, an expansion control valve should be fitted. If the PTR valve became blocked, the heater may eventually distort or fail.
  • The fitting of an ECV is mandatory in WA, SA and some other areas of Australia as dictated by local regulations.

Keeping in mind that a water heater is a pressurised container, we can use the above example to understand that an ECV is an added safety protection for the consumer. An ECV should be fitted on installation in areas where scaling is a problem.

Current research is showing that 80% of hot water burns occur in the bathroom. By the provision of various valves, this hazard can effectively be prevented.

Code requirements
AS 1056.1
With reference to clause 3.2.2 the thermostat for a storage water heater shall be set at not less than 60°C. This clause then explains that a minimum setting of 60°C is specified so that bacteria Legionella Pneumophillia do not survive in temperatures above 55°C.
AS 3500.4
1.9.2 Sanitary fixtures delivery temperature
All new heated water installations shall, at the outlet of all sanitary fixtures used primarily
for personal hygiene purposes, deliver heated water not exceeding—
(a) 45°C for early childhood centres, primary and secondary schools and nursing homes
or similar facilities for young, aged, sick or people with disabilities; and
(b) 50°C in all other buildings.
NOTE: Temperature limits are required to minimize the risk of scalding.

Length of exposure to hot water to cause scalding

  • at 50°C, a deep scald takes 5 minutes in an adult or child
  • at 54°C, a deep scald takes 35 second in an adult and 10 seconds for a child
  • at 60°C, a deep scald takes 6 second for an adult and 1 second for a child
  • at 65°C, 2 seconds for an adult and 0.5 seconds for a child
  • at 70°C, in a typical factory setting - 1 second for an adult

The outlet temperature from a domestic mains pressure water heater can be as high as 75°C, and as most people bathe in 43°C, there is an obvious need to temper and dilute the hot water being supplied to domestic bathroom fixtures. To comply with the requirements of AS 1056.1 and AS 3500.4, a temperature control system needs to be installed on all new hot water supply systems.

Tempering valves
An adjustable tempering valve can be installed into the hot water supply line incorporating all household hot water outlets. This will provide tempered water to all hot water fixtures at a temperature that will guard against scalding.
An installation option is to incorporate this valve to deliver tempered water only to hot water outlets in bathrooms and ensuites. The configuration of existing hot water lines may need to be altered.
The provision of a tempering valve will allow plumbers to set the tempered water outlet between 35°C and 50°C, to suite the customer’s requirements. By following the instructions, the temperature setting can be adjusted within the range to suit any change in requirements. A tempering valve is not a serviceable item and should be replaced every 5 years.

Thermostatic mixing valves
A higher cost option is a thermostatic mixing valve. These valves can supply temperatures selected between 15°C and 45°C. Clause 3.7 in AS 2500.4, highlights relevant information including installation instructions, isolating assemblies, commissioning, and maintenance guidelines. The valves can be installed with one application per bathroom, or a multi point installation depending on the positioning of hot water outlets, and the configuration of existing pipework.

Summary
It should be acknowledged that recent litigation proceedings have placed a “deed of care” onus on the plumber to ensure the safe application of hot water in domestic situations.
Industry awareness and media coverage of the issue of hot water scalding, combined with the AS 3500.4 standards, will ensure that the installation of valves to reduce the risk of scalding will become common in the industry.

Occasionally a service inquiry is made by a customer concerning a phenomenon where the water out of their hot water system is milky or cloudy.
The following points will explain the reason for this. This explanation should be passed on to the customer:-

  1. All tap water contains dissolved gases;
  2. Water under pressure can hold more dissolved gas than water open to atmosphere;
  3. When water under pressure is heated, its capacity to hold dissolved gas decreases. Hence, the cold water in the house may not be cloudy while the hot water is;
  4. Under certain circumstances where the dissolved gas in cold water under pressure is at a certain level and the water is heated, the hot water under pressure supersaturates with dissolved gases;

    This means that the gas may not come out of the solution in the container. It is at a critical stage and will certainly come out of the solution if the pressure is released. This is similar to the fizzing observed when the cap is removed from a bottle of soft drink;
  5. When the heated water pressure is released, the dissolved gas comes out of the solution (refer 2) in the form of tiny gas bubbles right throughout the water volume in the hot water which is collected out of the tap;
  6. The gas bubbles rise to the surface of the water and burst, so that the water has a milky appearance. This will clear in a few seconds, from the bottom up;
  7. Dissolved gas, ie. air in water in reasonable quantities is not uncommon and means that the water is in a "healthy" condition ie. rain splashing onto the surface of a storage reservoir increases dissolved gas content;
  8. Hot water storage systems which contain a magnesium anode which have not been used for some months, may display a similar phenomenon of milky water. This is caused by the dissolved gas being topped up with dissolved hydrogen. The hydrogen is only a small percentage of the total dissolved gases in the solution. This gas comes out of the solution as above, and is no cause for concern;
  9. This phenomenon is not confined to vitreous enamel type storage containers. It has been observed in all types of hot water storage vessels;
  10. The presence of dissolved gas which comes out of the solution at the tap does not indicate a fault in the hot water system. It indicates a healthy hot water supply and the gas bubbles presence will increase with the temperature of the hot water supply;
  11. If a customer insists that they require an alternative to having milky water, the hot water system could be open vented and converted to a low pressure hot water system.

The above explanation will be applicable in most cases. In situations where the problem appears to be worse than the above scenarios, it is possible that there may be other causes. These causes, reasons and their solutions are as follows:-

  • water quality in the area requires installation of an aluminium anode, ie. in hard water areas where the TDS level of the water exceeds 600mg/L. In these areas the magnesium anodes installed as standard may corrode too quickly.
  • the anode is not fully tightened into the tank socket resulting in poor electrical contact. The solution is to tighten the anode.
  • previous replacement of anodes may have caused damage to the enamel lining in the area of the anode socket which is also adjacent to the point where the draw-off tubes will extract hot water from the unit. In efforts to protect a bare patch of steel caused by the damage excessive anode activity may lead to "fizzing" in the same place that water is been drawn off. If this occurs anodes will have uneven decomposition or "necking", especially at the top. This situation does not, other than for the milky water, present a problem for the life of the water heater while anodes are replaced on a regular basis.

A common question we are asked is whether or not the installation of a storage water heater should include the use of a pressure limiting or pressure reducing valve.

At present, unless local regulations demand, there is no "legal" requirement to include these valves in the installation of a hot water reticulation system.

However, from a technical point of view some means of inlet water pressure control should be included where the possibility exists that the mains water pressure may, at any time of the day (especially at around 3 am in the morning when water usage in the area is low and therefore pressure in the mains is high) exceed 80% of the rating of the Pressure & Temperature Relief (PTR) Valve. Failure to install a pressure control device in this situation may lead to excessive discharge of water from the PTR Valve and apply undue stresses on the water heater's internal storage tank (thereby limiting its useful life - after corrosion, pressure spikes and metal fatigue are the greatest enemies of the mains pressure storage water heater).

The protection of the water heater and possible extension of its lifespan in addition to the ability to minimise the "waste" of water from PTR Valve discharge are features that may be used to encourage the householder to invest in the installation of pressure control devices.

As a hint when installing pressure control devices consider the positioning of these so that large differences between hot and cold water pressures do not make it impossible to safely adjust water temperature and flow, for example, in the shower. Where mismatched pressures become a problem it may be better to provide pressure control for all water on site via a device installed immediately after the water meter at the property boundary.

The Valve Application Guide provides assistance in choosing the correct model and rating of Pressure Limiting Valves for Dux Electric and Gas Storage Water Heaters.

For further information do not hesitate to call Customer Service 1300 365 115


"All that glitters is not safe"
Alternate title = "Beware the simple solution"

The introduction of the 50C regulation for hot water supply nationwide has seen the promotion of "simple" and "cheap" methods of compliance with the regulation. These include end-of-line devices, temperature flow switches and the reliance on temperature control panels to ensure that infants, the aged and infirm are not exposed to scald hazards.

While the simplicity and lower cost of purchase of these suggestions appears attractive at face value you should remind yourself that ultimately you, as the installer, are responsible for the safety of the installation. You need to convince yourself that these offer 100% foolproof, failsafe protection before using them and also that they are at least as reliable as devices specifically designed for this purpose such as tempering valves.

A simple yet effective means of assessing this is whether the protection device is able to pro-actively monitor and provide timely control of the water temperature and sudden changes in water temperature immediately prior to the point of use. Tempering valves can do this whereas many of the "simple and cheap solution" devices are oblivious to the conditions at point of use, rely on correct positioning and householder operation; and can only control water temperature at the outlet of the water heater which may be positioned many metres from the point of use.

The other question to ask yourself is:
What would you put in your own home to protect your family?
Surely your customers deserve the same consideration.

Scalding Hazards

The risk of hot water scalding is a moral and legal obligation (check local authority regulations) which should be considered when specifying any water heater. Below are some general tips:

  • User requirements should be determined to ensure the lowest temperature that provides sufficient hot water is set at the thermostat.
  • Various devices are available to restrict the temperature at the outlet/specific outlets. In some states these types of devices are mandatory for outlets in the bathroom (check local authority regulations).

Some of these are:

  • Thermostatic Mixing Values - these mix the hot and cold water to the desired temperature.
  • Tempering Values - also mix the hot and cold water to outlets throughout the application.
  • Over-temperature cut-out devices - these stop the flow of water at a preset temperature.
  • The user should be informed of the availability of such devices when discussing their requirements for hot water.
  • It is important to be informed on this issue and your Dux representative can assist you with your enquires.
  • Dux always recommend installation and servicing by a licensed tradesperson

Scalding prevention


  • Problems are Opportunities !
  • Children under five have a one in two hundred chance of being hospitalised because of scalding by hot water in the home.
  • Australian Standard AS3500.4:2015 cover these issues in detail

1.9.2 Sanitary fixtures delivery temperature
All new heated water installations shall, at the outlet of all sanitary fixtures used primarily
for personal hygiene purposes, deliver heated water not exceeding—
(a) 45°C for early childhood centres, primary and secondary schools and nursing homes
or similar facilities for young, aged, sick or people with disabilities; and
(b) 50°C in all other buildings.
NOTE: Temperature limits are required to minimize the risk of scalding.
1.9.3 Acceptable solutions for control of delivery temperatures
The following shall apply:
(a) The installation is deemed to comply with Clause 1.9.2(a) if all sanitary fixtures used
primarily for personal hygiene purposes are supplied from a thermostatic mixing
valve complying with AS 4032.1 and adjusted to an outlet temperature not exceeding
45°C.
(b) The installation is deemed to comply with Clause 1.9.2(b) if all sanitary fixtures used
primarily for personal hygiene purposes are supplied from—
(i) a thermostatic mixing valve complying with AS 4032.1 and adjusted to an
outlet temperature not exceeding 50°C;
(ii) a tempering valve complying with AS 4032.2 and adjusted to an outlet
temperature not exceeding 50°C; or
(iii) a water heater complying with AS 3498 and marked with the following:

THIS APPLIANCE DELIVERS WATER NOT EXCEEDING 50°C IN ACCORDANCE WITH AS 3498
NOTES:
1 Temperature control devices require routine maintenance and performance testing.
Information on maintenance can be found in AS 4032.2.
2 It is the property owner’s responsibility to ensure that the routine maintenance is carried out.

  • Additional regulations may exist in your state and guidance on these should be sought before commencement of work.
  • Both AS 3500.4.2, Clause 1.9.1 and the standard for the design and manufacture of water heaters, AS 1056 Storage Water Heaters, Clause 3.2.2 state that ". the thermostat shall be set at not less than 60C." The need for this arises from the fact that Legionella Pneumophilia bacteria can survive in temperatures up to 55C. This apparent conflict with the Plumbing and Drainage Code means that some form of temperature limiting device needs to be installed before the outlet in bathrooms, en suite and other personal hygiene areas.
  • The apparent conflict regarding storage and outlet delivery temperatures between AS 1056 and AS 3500.4:2003.1.9.2 requirements can be resolved by installation of temperature control devices which include thermostatic mixing valves, tempering valves, end-of-line devices (the relevant advantages of each of these are beyond the scope of this article; refer Plumbers Connection back issues).
  • This problem should be therefore be seen as an opportunity.
  • That is, the scope for more creative plumbing configurations on water heater installations allows the plumber willing to do their homework to both meet the requirements of the code and provide an even more flexible hot water system installation than ever before.
  • In addition to temperature control devices consideration should be given to the thermostat setting on the water heater when designing a hot water reticulation system. A lower storage temperature will reduce heat losses from the tank but will also reduce the thermal energy stored in the unit and this could lead to the user running short of hot water (ie, the warmer the water the more that will be drawn from the tank in relation to cold water mixed with it to achieve desired shower temperatures etc.). Similarly, a higher storage temperature than required to satisfy the household's hot water quantity and temperature needs translates to added running costs through increased heat loss and added wear-and-tear on the water heater through metal fatigue and enamel solubility.
  • AS 3500.4:2003, Clause 4.14

4.14.1 Design and installation
Heated water pipes in a non-circulatory heated water services shall be designed and
installed to—
(a) reduce to a minimum the amount of dead (cold) water drawn off before hot water
commences to flow at any tap;
(b) be sufficient to give the required flow at all outlets (including branches from noncirculatory
services);
(c) be by the shortest practicable route for the main flow heated water pipes and branches
to the heated water outlets;
(d) be the minimum necessary diameter of the heated water pipes required to supply the
outlet drawoff; and
(e) provide a water velocity not exceeding 3 m/s.

  • The other issue to keep in mind is your common law obligations regarding "duty of care" which essentially mean that via your expertise and qualifications you have the responsibility that any hot water installation you have worked on is "safe" in terms of the code. This "duty of care" includes the obligation to advise your clients of the issue of "scalding" and also provides the opportunity to discuss possible solutions with them.
  • By now you should be visualising the opportunities and be less concerned with the content of the new code. In preparing your approach to your next hot water installation don't forget that all Dux Proflo and Prodigy ranges of gas and electric storage water heaters have dual inlets and outlets providing flexibility of installation positioning in tight and unusual positions. They also have the facility for dual outlets; one supplying hot water to temperature control devices for supplying personal hygiene areas and the other to areas such as the kitchen and laundry where piping hot water above 50°C is needed.
  • In your efforts to provide a flexible and high performance hot water reticulation system using this feature don't forget the issues of flow volumes and velocities when sizing pipework ! Guidance on the typical flow rates required by various types of hot water outlet points and the details involved in multiple outlets operating simultaneously is provided in AS 3500.4
  • The old adage that "the difference between a good and bad plumber is the amount of silicone used" no longer applies. The benchmark will become the safety, performance, flexibility and cost of hot water reticulation systems and the way the code is applied to capitalise on the new opportunities in what is becoming a specialised field.
  • For further information contact Dux on 1300 365 115.

During winter months we may experience problems with gas water heaters, reported as "stacking", "dumping" or "overheating". These problems manifest themselves as large quantities of water being discharged through the Pressure and Temperature Relief (PTR) valve.
If units experiencing these problems are encountered, the following actions should be taken in the order listed until the problem is solved.

1. Check the quantity of water being discharged:-

  • if <20 litres/24 hours, advise customer that this is normal operation of the valve in relieving expansion pressures as water is heated ( ~ 3% of stored volume will be discharged)
  • if >20 litres/24 hours, check operation of PTR valve. Replace if faulty

2. Confirm that the correct size unit for the customer's family size and hot water usage patterns has been installed (refer sizing guide on brochures or in Dux Technical Manual);

3. Check the unit’s thermostat setting matches hot water needs. A setting of "3" or "medium" should be suitable if correct size unit is installed. If setting is higher than this, turn the setting down and advise the customer of the need to adjust thermostat up gradually (if a mid range setting is not suitable) until they are satisfied;

4. Check that the Gas Controller in the unit is either a Unitrol (23 - 63°C) or EUROSIT (24- 64°C) and that it is functioning correctly. Replace if necessary.

5. Check that a flue baffle is present in the unit; that it is of the correct length and that it has not fallen down into the flue (i.e. it should be hanging by tabs from the top of the flue tube).

6. Confirm correct installation and commissioning of the unit with respect to -

  • inlet water pressure and the use of Pressure Limiting valves where inlet pressure may exceed maximum inlet pressure shown on unit's data plate
  • gas test point pressure and
  • injector sizes (if unit has been converted from another gas type

(Refer "Dux Owner's Manuals for details)

7. Contact the Service Department for further instructions on data to be collected to assist in further investigations.

Dux Gas Water Heaters are supplied as standard with thermocouples as part of the pilot burner assembly. These thermocouples are also available as spare parts either as a separate item or as part of a complete pilot assembly. When ordering spare parts, it is essential that the correct part is requested - they are not interchangeable between different heaters.

The specific details and differences between the thermocouples are outlined below:

Thermocouples for Prodigy3 External models:
• Dux Part # = H0046 (Robertshaw Unitrol Gas Controller)

Thermocouples for all units fitted with Eurosit 630 Gas controller
• Dux Part # = H8349

A "hot topic" of the moment is the need to limit the temperature of hot water supplied to outlets primarily used for hygiene purposes so that infants, the aged and the infirm are safe from the hazards of scalding.

One of the areas of confusion that arises from the need to adhere with the regulations limiting the hot water temperature at the outlet in new buildings is that many householders request that the thermostat on their water heater be turned down to less than 50°C. It should be noted this is not possible since the Standards and regulations applicable to storage water heaters specify a minimum storage temperature of 60°C for reasons of preventing the breeding and growth of Legionella bacteria.

Other issues with setting the thermostat on low temperatures are is that in some areas in the house e.g. the kitchen, the water may not be hot enough for certain tasks; and that more hot water will be drawn from the tank to supply the desired temperature since less cold water will be needed to be mixed with it to "cool" it back to the required temperature - the unit will therefore run out of hot water sooner.

The various tempering devices available on the market properly installed on a storage type unit with the thermostat set at a mid range temperature can overcome all of these problems while still allowing the facility to adjust the thermostat up in winter or when more hot water is needed.

Remember: the higher temperature at which the water is stored the further it goes when mixed with cold water to achieve the required temperature at the outlet.

The right size Dux storage unit installed correctly and with proper adjustment of thermostats and tempering devices will provide more than enough hot water for any household.

RMC Valves

DUX ELECTRIC MODELS Pressure & Temp Relief Valve
(PTR)
Expansion Control Valve
(ECV)
Pressure Limiting Valve
(PLV)
25 Litre HT55 1000Kpa H50 850Kpa PSL50 500Kpa
50 Litre HT55 1000Kpa H50 850Kpa PSL50 500Kpa
80 Litre HT55 1400Kpa H50 1200Kpa PSL50 500Kpa
125 Litre HT55 1400Kpa H50 1200Kpa PSL50 500Kpa
160 Litre HT55 1400Kpa H50 1200Kpa PSL50 500Kpa
250 Litre, Single Element HT55 1000Kpa H50 850Kpa PSL50 500Kpa
250 Litre, Twin Element HT55 1000Kpa H50 850Kpa PSL50 500Kpa
315 Litre, Single Element HT55 1000Kpa H50 850Kpa PSL50 500Kpa
315 Litre, Twin Element HT55 1000Kpa H50 850Kpa PSL50 500Kpa
Pre October 99      
400 Litre, Single Element HT55 850Kpa H50 700Kpa PSL50 350Kpa
400 Litre, Twin Element HT55 850Kpa H50 700Kpa PSL50 350Kpa
400 Litre, TITAN HT55 850Kpa H75 700Kpa PS75 350Kpa
Post October 99      
400 Litre, Single Element HT55 1000Kpa H50 700Kpa PSL50 350Kpa
400 Litre, Twin Element HT55 1000Kpa H50 850Kpa PSL50 500Kpa
400 Litre, TITAN HT55 1000Kpa H75 850Kpa PS75 500Kpa

 

DUX GAS MODELS Pressure & Temp Relief Valve
(PTR)
Expansion Control Valve
(ECV)
Pressure Limiting Valve
(PLV)
105 Litre, "Forte & Marathon" HTT55 1400Kpa H50 1200Kpa PSL50 500Kpa
145 Litre, "Forte & Marathon" HTT55 1400Kpa H50 1200Kpa PSL50 500Kpa
185 Litre, "Forte & Marathon" HTT55 1400Kpa H50 1200Kpa PSL50 500Kpa
Pre Nov 98      
90 Litre "Proflo" "Square units" HTT55-1 1400Kpa H50 1200Kpa PSL50 500Kpa
135 Litre "Proflo" "Marathon" "Square units" HTT55-1 1400Kpa H50 1200Kpa PSL50 500Kpa
170 Litre "Proflo" "Marathon" "Square units" HTT55-1 1400Kpa H50 1200Kpa PSL50 500Kpa
Post Nov 98      
90 Litre "Proflo" "Square units" HTT55 1400Kpa H50 1200Kpa PSL50 500Kpa
135 Litre "Proflo" "Marathon" "Square units" HTT55 1400Kpa H50 1200Kpa PSL50 500Kpa
170 Litre "Proflo" "Marathon" "Square units" HTT55 1400Kpa H50 1200Kpa PSL50 500Kpa