Commission and maintain hot and heated water temperature control devices

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3 ACKNOWLEDGEMENTS National Plumbing Services Training Advisory Group Plumbing Industry Commission Victoria Commonwealth of Australia 2015 Construction and Property Services Industry Skills Council PO Box 151 Belconnen ACT 2616 Tel: This work is copyright, but permission is given to trainers and teachers to make copies and contextualise the resources for use within their own training organisation or in a workplace where training is being conducted. This permission does not extend to making copies for use outside the immediate training environment for which they are made, or the making of copies for hire or resale to third parties. The work was first published in 2006 with the assistance of funding provided by the Commonwealth Government, through the then Department of Education Science and Training (DEST). The 2015 publication has been updated to reflect changes to the national units of competency. The views expressed in this work do not necessarily represent the views of the Commonwealth of Australia or CPSISC. In addition, the Commonwealth of Australia and CPSISC do not give warranty or accept any legal liability in relation to the content of this work. The website addresses and other contact information provided in this publication were compiled in good faith and were correct at the time of printing. The updating of these resources was completed by: National Plumbing and Services Training Advisory Group, with funding and support provided by the Construction and Property Services Industry Skills Council (CPSISC): This guide was developed in consultation with representatives of the Plumbing Industry by NPSTAG and CPSISC to support the implementation of the CPC08 Construction, Plumbing and Services Training Package. Commonwealth of Australia

4 Acknowledgements Project reference committee: Writer: National Plumbing Services Training Advisory Group Mark Hollywood Technical editor: Instructional designer: Graphic artist: Word processor: Max Garbin Judie Litchfield Laura Bito Melissa Rogers 2 Commonwealth of Australia 2015

5 Contents Before you begin... 4 Introduction Overview of hot water systems and temperature control devices What makes a good hot water system? Types of hot water temperature control devices Thermostatic mixing valves and tempering valves: mechanical principles Thermostatic mixing valves and tempering valves: operating principles Actuating devices Hydraulic principles of thermostatic mixing valves Characteristics of thermostatic mixing valves Application of thermostatic mixing valves Preparing for work Gathering information Determine workplace and equipment safety requirements Planning to test and commission Selecting tools and equipment Commissioning and servicing Servicing thermostatic mixing valves The service report Commissioning thermostatic mixing valves Commissioning, servicing and maintaining tempering valves Restore the work area Final assessment activity Commonwealth of Australia

6 Before you begin Welcome Welcome to the learning resource for the unit Commission and maintain hot and heated water temperature control devices. This resource will help you develop the knowledge and skills you need to demonstrate competence in the unit. A learning resource such as this is not intended to be the only source of information you use to develop skills and knowledge in the unit it relates to. Your trainer, instructor or supervisor will provide you with additional information and information sources throughout your training. Flexible delivery Your trainer, instructor or supervisor for the unit may adapt and deliver this learning resource as required to suit people from a range of backgrounds and in diverse learning environments (such as rural and isolated settings). This will assist in meeting equity principles and conforming to legislative policies. How to use this resource This resource addresses the underpinning knowledge and skill development required to help you commission and maintain hot water temperature control devices. It contains: information on commissioning and maintaining hot water temperature control devices activities designed to encourage you to check and confirm your learning along the way and to help you complete the final assessment a summary of the final task or tasks you must complete to be assessed as competent in this unit. Your assessor will give you additional specific detail required for your final assessment activity in line with state and territory regulations and industry requirements. The resource has been developed for use in a variety of ways. Your trainer, instructor or supervisor will advise on how best to use it during your training, which may include: trainer-centred, class-based study home-based, self-directed study activities in the workplace. 4 Commonwealth of Australia 2015

7 To complete the unit Commission and maintain hot and heated water temperature control devices you may be required to: read the information in this resource complete the resource activities as directed and submit your answers for review or discussion with your trainer, instructor or supervisor work with your trainer, instructor or supervisor to practise carrying out work-based risk control processes read the final assessment summary together with any additional assessment information your assessor provides complete the final assessment. Your assessment in this unit It is important to note that the role of the assessor in assessing units of competence is quite separate from the role of trainer, instructor or supervisor. Your assessor for this unit may or may not be the same person as the trainer, instructor or supervisor who worked with you during your training. However, your assessment must always meet the requirements of the unit. You will find references to trainers, instructors or supervisors and assessors throughout this resource depending on the context. Assessment in this unit will require you to demonstrate the skills and knowledge needed to commission and maintain hot water temperature control devices. Table 1 on page 3 suggests the variety of assessment methods that may be used to assess your competence in this unit. In many instances, your assessment may involve a combination of methods to ensure the validity, reliability, flexibility and fairness of the process. If you have any questions about your assessment please discuss them with your assessor who will decide with you the specific details of what you will do. An assessor may develop specific assessment strategies to meet the particular requirements of learners from diverse backgrounds. This unit may be assessed in conjunction with assessment for other units of competence. In such a case, assessment might be based on a task or tasks related to a project that more closely resembles workplace activities. An appropriate unit for such project-based assessment might be one that naturally forms part of your workplace responsibilities and roles. Your assessor will decide if you are to be assessed in this way and will advise you. Commonwealth of Australia

8 Assessment methods Key Assessment method Description QS Questioning oral/written Assessor will ask a range of questions from a moderated bank of questions that support the underpinning skills and knowledge required to achieve competency in this unit. Questions may be answered in written or oral form. WN Written notes Learner will complete written notes, activities or student resource materials to support the achievement of underpinning knowledge required to achieve competency in this unit. TB Test bank Learner will complete computer test bank assessment which supports the underpinning skills and knowledge required to achieve competency in this unit. PO Practical observation Assessor will observe the learner completing practical task(s) that meet the assessment criteria to the required specification in the workplace. DM Demonstration Assessor will observe the learner completing practical task(s) that meet the assessment criteria to the required specification in a simulated work environment. CS Case study/project Learner will complete workplace-based projects or case study reports to support the underpinning skills and knowledge required to achieve competency in this unit. LB Logbook Learner will provide evidence of practical work and/or assessment tasks completed at the workplace via personal logbook. 3P Third party report Assessor will seek report from learner s workplace employer, supervisor or other approved party on the performance of a learner in the workplace against assessment task criteria and requirements of the unit. WD Workplace documents Learner will provide copies of workplace documents to support the underpinning skills and knowledge required to achieve competency in this unit. Table 1 Assessment methods 6 Commonwealth of Australia 2015

9 Prerequisites units There are no prerequisite units for this unit. However, this unit has a relationship with the unit CPCPCM4011A Carry out work based risk control processes. Additional resources The following resources have been suggested that may help you undertake training and assessment in this unit. Texts Building Code of Australia Plumbing Code of Australia Australian Standard AS/NZS 3500 Plumbing and drainage Australian Standard AS Water supply Valves for the control of hot water supply temperatures Websites Video or audio resources Commonwealth of Australia

10 Introduction To demonstrate competence in this unit you will need to show the level of skills and knowledge required to test, commission and maintain hot water temperature control devices. This will include thermostatic mixing valves in water services. The location for the work will be residential or commercial, and may be a new worksite or an existing structure being renovated, extended or restored. Each section has activities that will enable you to test your knowledge. Before you begin to test, commission and maintain hot water temperature control devices, you need to know how they work. If you find you are not sure of some areas, talk to your trainer, instructor or supervisor. Assessment for this unit will require you to do at least the following: Test, commission and maintain three different types of hot water temperature control valves, including at least one thermostatic mixing valve type, indicating maintenance requirements. For each type of control valve, you will need to correctly identify the location, design and details of the proposed service and correctly select an appropriate valve for the application. All your work must be to specification. It must also comply with regulations, standards and organisational quality procedures and processes. 8 Commonwealth of Australia 2015

11 1. Overview of hot water systems and temperature control devices Temperature control devices are part of a hot water system that has the job of delivering warm or hot water to plumbing fixtures. In this section, we will examine: the desirable qualities of hot water systems types of temperature control devices mechanical principles of thermostatic mixing valves and tempering valves operating principles of thermostatic mixing valves and tempering valves types of actuating devices hydraulic principles of thermostatic mixing valves characteristics and applications of thermostatic mixing valves. 1.1 What makes a good hot water system? Below are ten qualities you should look for in a hot water system. It should not harbour any harmful bacteria. It should work quietly. It should not accelerate corrosion of metallic parts on tapware, valves or piping. It should not promote build-up of sludge in storage vessels. It should not be seen. It should be as cost-efficient and environmentally friendly as possible. It should not cause nuisance to people or damage to property. Hot water should start to flow from the taps within 30 seconds from initial turn-on, to reduce the wasted once was hot water that goes down the drain. Dead legs (closed-off pipes where cold water and bacteria can accumulate) should be of minimum length and diameter. The water should not be hot enough to burn human skin. The hot water should be delivered at sufficient flow and pressure, ideally, the same as for the cold water tap. (This is difficult to maintain due to pressure variances at dynamic flow.) Commonwealth of Australia

12 From the above, it is easy to see the dilemma of storing hot water at above 60ºC, but delivering it at below 50ºC. 1.2 Types of hot water temperature control devices So how do we control the temperature of hot water to sanitary fixtures? There are five ways this can be done, using: tempering valves thermostatic mixing valves temperature activated end-of-line devices warm water units continuous flow hot water units (electronically controlled). Tempering valves (TV) A tempering valve is a device that ensures the delivery of hot water at a specified temperature to an outlet, by mixing streams of hot and cold water to provide a cooling affect. Tempering valves were manufactured to comply with the old AS 1357 but this code now forms part of AS 4032 (Part 2). Thermostatic mixing valves (TMV) A thermostatic mixing valve is a device that provides the user with a simplified means of mixing hot and cold water to the desired temperature. Thermostatic mixing valves Tempering valves ± 2ºC on a test rig ± 3ºC on a test rig Typically a larger valve as it will often have isolation valve, line strainers and non-return valves on both hot and cold supplies. (Although there are some very compact valves now on the market). Small and compact device. Thermal shut down testable with separate isolators hot and cold. Not thermal shut down testable. 10 Commonwealth of Australia 2015

13 Thermostatic mixing valves Repairable. Usually a maximum of 80ºC hot supply and 45ºC blend temperatures. (NB: These valves can usually handle higher temperatures than this. This is just as tested under AS 4032). Tempering valves Non-repairable. Can handle 99ºC hot supply and can be adjusted up to 50ºC. Many of these valves are approved for health care installations. More highly priced and can be bought with many accessories, such as lockable stainless steel boxes and test points. Not typically health care approved. Aimed more at the domestic and commercial markets. Not as highly priced but by no means cheap and nasty. These valves perform very well and can give many years of service. Table 2 Differences between thermostatic mixing valves and tempering valves Temperature activated end-of-line devices These devices are less favoured in the industry because one is needed at every outlet. Nevertheless, they still comply with the requirements of AS/NZS Warm water units Warm water storage units and the heat exchange design for these systems must comply with the Public Health (Microbial Control) Regulation They can also be signed off by an engineer or are required to carry manufacturer compliance certificates. Instantaneous hot water units (electronically controlled) If these systems are factory set to a maximum of 50ºC, they do not need any additional device (such as a tempering valve). The units are also available as a 43ºC system (ie for warm water) and are approved for installation in health care buildings. Commonwealth of Australia

14 Activity 1 Temperature control devices are part of a system designed to deliver hot/warm water to plumbing fixtures. In the space provided, describe the features of a good hot water system. 1.3 Thermostatic mixing valves and tempering valves: mechanical principles How do you maintain and service something if you have no idea how it works? This section will provide you with a basic knowledge of the operating principles of thermostatic mixing valves and tempering valves. First, it is important to note that mixing and tempering valves are standalone, in that they need no external power source. The operating energy they use is simply the temperature difference between the hot and the cold water supplies. Basic principles of operation In the diagram that follows, note the thermostatic (wax) capsule. This capsule is always located in the downstream blend zone of the device, and when it is heated, its actuating pin expands. This moves the slide shuttle from the cold seat to draw water from hot and cold supplies simultaneously. Therefore, at any blend point in the capsule s operation, the force it exerts is exactly counteracted by the force of the return spring. These mechanical forces cancel each other out and the slide shuttle is left at somewhere between the hot and cold seats, resulting in a warm water mix. 12 Commonwealth of Australia 2015

15 The diagram, sourced from the Hosplan Code of Practice for Thermostatic Mixing Valves in Health Care Facilities (NSW), shows this principle, though in reality the design of the valves is more complex. Figure 1 Operation of thermostatic mixing valves and tempering valves Diagram notes 1. On start-up from ambient cold, the wax element is fully withdrawn, closing the cold port but allowing the hot port to be fully open. This enables a quick purge of the hot dead leg to the TMV from the storage tank or the hot circulatory pipe work. 2. There is no failsafe device and there never has been. Failsafe test means thermal shutdown test. The process works by shutting off the cold supply to the TMV during operation, generating a large mechanical force in the wax element. In turn, this pushes the shuttle tightly onto the hot seat. Result no hot flow/no cold flow = no flow condition. The thermal shutdown test is still an important step in the commissioning process, but it does not show that during normal operation the valve will automatically shut off if it senses an over-temperature condition. It will not. Any TMV with a mechanical or out of adjustment can run up to a full hot water condition. Commonwealth of Australia

16 What do the devices achieve? If someone showering loses track of where the taps are (left/right, clockwise/anti-clockwise), a properly operating valve will protect them from water that is hot enough to burn them. This is the most important job for these devices, and they perform it many thousands of times. If the device is working satisfactorily, but somehow the cold water is isolated and the hot water is not, the device will stop water flow, again preventing a possible burn. If a person having a shower accidentally bumps the cold water tap, the valve protects them by delivering water only to the set temperature. 1.4 Thermostatic mixing valves and tempering valves: operating principles As noted earlier, these devices operate as stand-alones, with the energy that makes them work coming from the temperature difference between the hot and cold water supplies. Ideal temperatures are around 20 C cold, 40 C warm and 60 C hot. Pressure difference between hot and cold should be within 10% (for both static and dynamic conditions) for best valve performance. If the cold water supply pressure is 400 kpa, a maximum of 440 kpa with a minimum of 360 kpa for the hot supply is acceptable. The wax element provides the force that lets the valve work. Made of beeswax and fine copper particles, it is always located in the downstream blend zone of the device. When cold, the element will always hold the shuttle in the fully open to hot and closed to cold position. Usually, total movement of the shuttle is less than one millimetre. When the valve is in use, the energy created by the wax element pushes the shuttle to a mid-blend position, allowing both hot and cold water to flow at the same time. Mechanically, at this point the force created by the wax element is directly proportional to the force of the return spring. If the cold water is suddenly shut off during flow, the energy of the wax element is far greater than the energy of the return spring and the valve prevents any water flow (thermal shutdown test). 14 Commonwealth of Australia 2015

17 The valve does not have a failsafe, but operates as a safety device, giving excellent protection against accidental scalds. All valves change temperature slightly due to flow changes across the valve or pressure changes supplying the valve. Every one of these devices is a direct cross-connection between the hot and cold water supplies and will, without fail, track water from one to the other without the need of a correctly operating non-return valve. Activity 2 In this activity you will test your understanding of how thermostatic mixing valves and tempering valves work. Obtain a wax element from a thermostatic mixing valve or tempering valve. Hold the element in the jaws of a set of multigrips and place it under a hot water tap. Note the force created at the multigrips handles. Then place the element alternately under the hot/cold taps. Note how the element works the handles back and forth. Write in your own words what you have done and what the results show. Commonwealth of Australia

18 1.5 Actuating devices An actuating device provides the force that makes the valve work. There are three basic types of actuating devices: wax capsule thermoscopic element bimetallic element. Wax capsule This capsule is 100% full of beeswax and fine copper particles. The beeswax has quite a high expansion rate and can sense a temperature change to 1 C for minor adjustments. The copper particles conduct heat quickly into the element s core to aid a fast response, which eliminates a dramatic temperature overshoot on startup. By contrast, the wax capsule is a slow heat conductor. The expanding wax in turn pushes the shuttle to a new position via an actuating pin. Because the wax element is in the downstream zone, it reacts immediately and moves the shuttle. Most TMVs available use the technology just described, as it has proven to be reliable and accurate. Figure 2 Thermostatic wax element Thermoscopic element Instead of wax, the thermoscopic element has an alcohol liquid captured in a copper coil to sense temperature change. The liquid expands into a bellows, which in turn adjusts the slide valve shuttle. 16 Commonwealth of Australia 2015

19 These devices have proven accurate and very reliable, providing quite high flow rates. Rada is one manufacturer. Bimetallic element Figure 3 A thermoscopic element Bimetallic elements were the forerunners of the more modern systems described above and looked something like a stack of ten 20 cent pieces. At the time of writing, they are no longer used, as they did not have the performance of thermoscopic or wax element systems. 1.6 Hydraulic principles of thermostatic mixing valves The hydraulic principles relating to TMVs are quite complex (as is the associated pipe work), but you need to understand them. This section will give you some good ideas and general rules, but is by no means exhaustive as there are many variations in system design. All TMVs create a pressure drop as the manufacturing tolerances for total movement of the shuttle is in most cases less than one millimetre (as discussed earlier). As the flow increases across the valve, pressure loss increases, but this loss is not proportional to the flow. It cannot be straight-line graphed. Commonwealth of Australia

20 Below is a typical manufacturer s flow chart. It can be read in two ways: the pressure loss at a given flow rate the amount of flow at a given pressure. Figure 4 Manufacturer s flow chart The pressure loss at a given flow rate If you have a system of, say, three showers requiring eight litres a minute each, and these showers are all running, then the valve has to provide 24 litres a minute. On the chart, find 24 L/min and plot a vertical line up to the relationship curve and then plot a line horizontally to the pressure axis. You will find a pressure loss of about 170 kpa. At that flow rate, this valve will lose 170 kpa just at the valve. In reality, pressure should be much greater to allow for other system losses. 18 Commonwealth of Australia 2015

21 The amount of flow at a given pressure Conversely, let s say you want to know how many litres a minute will be available if the system has 400 kpa of pressure. To do this, you plot a line horizontally across from the 400 kpa line to the relationship curve and then vertically down to find about 37 L/min available at that pressure drop. Note, however, that choosing to read the chart in this way leaves no allowances for other system pressure losses. Further system pressure losses and hydraulic factors The following factors are all relevant. The thermostatic mixing valve. As you will see from any manufacturer s performance chart, this is the part of the system that loses the most pressure. Pipe lengths. The longer the pipe, the more pressure is lost over a given length (usually measured in metres per 100m of head loss.) Pipe diameters. The larger the diameter, the greater the flow, but the higher the losses and the longer the wait for hot water to start flowing. Pipe material. Frictional resistance of the internal surface and the nominal bore of pipes will differ. Flow in litres per second. The more flow, the higher the pressure drop. Water temperature. The hotter the water, the better it flows (but only to about 4% better from 20ºC to 60ºC). Percentages of flow. For temperatures of 20º C cold, 45º C warm and 70º C hot, the percentage proportions of flow are 50/50 hot to cold. Change any of these temperatures and the flow splitting percentages will change. Use the formula: Formula HV% = 100 * ( M C ) ( H C ) Where HV% = the percentage of hot water in the mix M = the temperature of the mixed warm water H = the temperature of the hot water C = the temperature of the cold water Commonwealth of Australia

22 Example The flow at the outlet of the TMV is 3 showers at 8 litres a minute each = 24 L/min 60 = 0.4 L/sec. To find the split of percentages of flow use: HV% = 100 x (M C) (H C) = 100 x (42 20) (80 20) = 37% This means 37% of the flow to this valve is hot, therefore 63% of the flow to this valve is cold. So 0.4 L/sec is split at 0.4 x 37% = 0.15 L/sec of hot water flowing to the valve; 0.4 x 63% = 0.25 L/sec of cold water flowing to the valve. Activity 3 Calculate the flow in L/sec for the hot and cold pipes shown on the diagram if the flow to the outlet is 40 L/min. Warm water temperature = 45ºC Cold water temperature = 20ºC Hot water temperature = 82ºC 20 Commonwealth of Australia 2015

23 Worked example What are the calculated losses to run this system at these flow rates at full flow with no diversity factor? One of the biggest debates about using smaller pipes is pressure loss. The sketch below shows a TMV serving three showers. This sketch should be viewed in conjunction with the pipe sizing calculations on the following page. Figure 5 A TMV serving three showers Notice the flow rates in litres per second and the two sets of pipe sizes. The top pipe size shown in the bubble is compliant with Hosplan for flow velocities of less than one metre per second. This is system A in the following calculations. The second given pipe size is for an AS/NZS 3500 compliant maximum velocity of three metres per second. This is system B in the following calculations. Commonwealth of Australia

24 Sizing method A (See top number in each bubble in Figure 5.) This method uses the Hosplan Code, and keeps flow rates in pipes to less than one metre per second and uses the same shower fittings at eight litres per minute. Pipe section Length in metres Velocit y in metres per second Flow in litres per second Diamete r (nomina l) in mm Pressur e loss in m/100 m Pressur e lost in kpa* C to TMV TMV inlet to TMV outlet From the given Grohe chart TMV to A A to B B to Sh Total system pressure losses from C to Sh 3 = 177 kpa * Actual length x m/100 m x 9.81 kpa/m = Pressure loss in kpa. (Calculations sourced from Selection and Sizing of Copper Tubes for Water Piping Systems by Barrie Smith.) Table 3 Sizing method A; using Hosplan code 22 Commonwealth of Australia 2015

25 Sizing method B (Bottom number in Figure 5.) This method uses a maximum velocity of three metres per second in pipes, and showers at eight litres per minute. Pipe section Length in metres Velocit y in metres per second Flow in litres per second Diamete r (nomina l) in mm Pressur e loss in m/100 m Pressur e lost in kpa* C to TMV TMV inlet to TMV outlet From the given Grohe chart TMV to A A to B B to Sh Total system pressure losses from C to Sh 3 = 245 kpa * Actual length x m/100 m x 9.81 kpa/m = Pressure loss in kpa. (Calculations sourced from Selection and Sizing of Copper Tubes for Water Piping Systems by Barrie Smith.) Table 4 Sizing method B How much wastage from each system? System A with its larger pipe sizes is ahead of system B in getting pressure up to the tap. If this system had 4 bar (or 400 kpa) to start with, then system A would have a residual at the most hydraulically disadvantaged outlet (shower 3) of 223kPa, and system B would have a residual of 155 kpa. Both systems would work but system A would have a pressure advantage of 68 kpa over system B. Although this pressure advantage might sound good it will, however, come at a cost. Commonwealth of Australia

26 Dead legs If you were to run, say, a DN 50 pipe up to a shower on the cold tap, it would make little difference other than the initial extra cost. You might get a little extra pressure, but 99% of the extra pressure would be lost at the tap anyway. There would be no extra running costs because when people turn on a cold tap for cold water that is immediately what they get. However, if this were a hot or warm water tap, there would be a huge waste because when people turn on a hot tap, hot water is what they want. The problem is that all the hot water in the dead leg has returned to ambient cold since the last use. The user purges all that once was hot water down the drain until hot water starts to flow. The result is a significant waste of water down the drain. But how much water? Wasting water System A Pipe section Length in metres Diamete r Litres per metre Capacit y in litres C to TMV TMV to A A to B B to Sh Actual Hot Water Dead Preheating of pipe before start up add 25% = Total hot water wasted = Table 5 Water wastage calculations: System A 24 Commonwealth of Australia 2015

27 System B Pipe section Length in metres Diamete r Litres per metre Capacit y in litres C to TMV TMV to A A to B B to Sh Actual Hot Water Dead Preheating of pipe before start up add 25% = Total hot water wasted = 1.97 litres Table 6 Water wastage calculations: System B Therefore system B uses litres less than system A. If you were to assume 20 litres start-up from dead per day in this system, then: System A = 20 x L = litres wasted System B = 20 x 1.97 L = 39.4 litres wasted. System B will still waste water but it is clearly 62 litres per day in front of system A. Annually, this equates to 22,667 litres, which is a lot of water to waste. Wasting time When we turn on a hot tap, we want hot water and will usually wait for it to come through the pipe, testing the temperature with our hand while waiting. How long a wait then? System A at litres to purge 8 L/min flow x 60 sec/min = 38 seconds. System B at 1.97 litres to purge 8 L/min flow x 60 sec/min = 15 seconds. Clearly, system B has 23 seconds less wait time and again if you add up by the day and by the year this equates to a lot of wasted time. Commonwealth of Australia

28 Wasting energy We all know water heating takes a lot of energy. In fact, it takes 4,200 joules to raise only one litre of water through 1 C. Let s calculate the yearly savings system B has over system A. Heat energy required = Volume of water x temperature difference x 4.2 kilojoules. = 22,667 x (80 20) x 4.2 Kj = 5,712,804 kilojoules = 5,713 megajoules (75 m³ LPG at 80% efficiency) = 1,587 kilowatts. However you look at these figures, they equate to a lot of energy. What about noise generated by water running through pipes at a higher velocity? Most noise is generated at the valves and taps and is often mistakenly believed to be from the pipes. However, it is actually the noise conducted along the copper pipes. Noise is associated with a high velocity and a sudden pressure drop, which is what happens across a TMV and to a more noticeable extent with single lever mixer taps. Single lever mixers in stainless steel sinks can be quite noisy if they are operating at a high pressure. The higher the pressure the louder the tap. Nicely installed, well-clipped, de-burred pipes with no sharp changes of direction rarely make much noise even at three metres per second. What about local authority requirements for pipe sizing? Can we run smaller bore pipes for hot water? There are a couple of things to remember with this issue. First, the requirement for the fixture to work under AS/NZS 3500 will be met by the cold water supplied to it. Quite simply, there is no mandatory requirement that you must have hot water at plumbing fixtures. Again, as stated earlier, this can be a complex issue, particularly when there is flow splitting for a fixture. The hotter the hot water, the less of it you need in a warm mix. 26 Commonwealth of Australia 2015

29 Notice from Figure 5 that the hot flow at 80 C with all three showers running is only slightly more than what comes out of one shower. Flow splitting means smaller pipes are adequate because the rest of the flow is supplied from the cold piping. Note See AS/NZS Clause 4.14 INSTALLATION OF HEATED WATER SERVICES. The following summarises the AS/NZS 3500 recommendations: shortest possible dead legs smallest possible pipe size (maximum velocity of three metres per second). Should these hot and warm pipes be insulated? Most plumbers would say lagging these pipes is not worth the effort as there is probably only a 1 C temperature loss over the length of a dead leg. This is mostly true, but that 1 C represents a 2% loss in straight run temperature. Also, if dead legs are insulated, the hot water takes much longer to drop back to ambient cold so many follow up tap usages may have no need for purging the dead leg to use the hot. Note See AS/NZS 3500 Clause 6.4 Heat retention. In summary of this pipe sizing dilemma, it would be fair to say that a larger pipe size gives better pressure to the taps, but a smaller size will still give the required flow while saving water, energy, money and time. You could also consider exceptional insulation or heat trace, or you could circulate the piping system. Commonwealth of Australia

30 1.7 Characteristics of thermostatic mixing valves There are basically two design characteristics the old and the new. You should make sure you can identify all valves by sight. They all look different and most valves in the field have no identification markings. The two basic designs incorporate a range of unique and individual design features. These features include: built-in pressure balancing valve, which could be an advantage where inlet pressures are known to fluctuate ease of servicing with, for example, only 2 O rings and 4 parts, as compared to 14 O rings and 26 total internal parts. very high flow rates to group more fixtures and save on the installation neat, compact and easily installed wall mountable in a stainless steel lockable box five year service intervals, as compared to the usual one year able to be retrofitted as either a single lever mixer or a thermostat cost effectiveness, supplier warranty and parts backup able to be retrofitted to an existing in-wall shower combination (single point chromed versions). This resource is not meant to direct you to any particular brand of valve. Each valve on the market is there because it has one or a few of the features purchasers want. The old design A typical old design TMV is the Grohemix (see the figure below). These devices were the forerunners of the modern designs and although manufacturers have updated their models, thousands of the devices are still working quite well and needing regular servicing. 28 Commonwealth of Australia 2015

31 Some of the problems with this style of valve, not necessarily related to performance, were: expensive to manufacture (heavy piece of brass required bracketing and lots of space to plumb it) not directionally adaptable for inlets/outlets if the valve body needed replacing, all the water had to be isolated to remove the valve. The new design Figure 6 Grohemix 20 mm Typical new design TMVs include the Horne, Aquablend (see the figure below), Broen and Grohe Series These designs have some very real advantages over the old: easy to manufacture, reducing cost lightweight and very easy to plumb in almost any position easy to commission/maintain. Commonwealth of Australia

32 Figure 7 Enware Aquablend Application of thermostatic mixing valves Thermostatic mixing valves are used to mix hot and cold water supplies in the correct proportions to maintain warm water at a constant temperature, regardless of flow, to connected fixtures. As discussed earlier, they are not failsafe, but will still do the job of limiting water temperature to those fixtures, and will normally do this task quite well. There are basically two applications single point and multipoint. Single point In a single point application, the valve only controls the temperature of the water to one fixture. The valve can be located in the wall (accessible by an access panel) or in a vanity cupboard. There are designs suitable for surface mounting in a shower, where it is difficult to access piping. These valves serve only the one outlet and usually have a low flow rate. Many have a thermostatic adjustment the customer can use. The temperature is usually set for a maximum of 38 C at a lock button and 45 C when the button has been depressed. 30 Commonwealth of Australia 2015

33 Multipoint Most valves are sold for multipoint installation as it is obviously more cost effective to group fixtures together. The table below shows some of the places you find these mixing valves. Device Thermostatic mixing valves Tempering valves End of line temperature activated Domestic (eg housing, units) Not usually used here due probably due to higher cost. Used extensively on new and many retrofits. Used sometimes. Isolation procedures Commercia l (eg hotels, hostels, motels, sporting facilities) Yes. Used in the more expensive hotels along with quality tapware. Yes. Used in hostels, caravan parks and motels. Used sometimes. Table 7 Common usage of mixing valves Hospitals (nursing homes, government and nongovernment homes for disabled) Yes. Used extensively in this field. Could be used but does not normally comply with governing bodies requirements. Probably never (never say never). Any plumber can shut off a water supply, but make sure you check that people are not using or planning to use ablutionary fixtures. Tag such fixtures with Out of order signs and let those in charge know how long the work will take. If the cold water is isolated and the hot water is not, someone showering may be scalded if the thermostatic mixing valve is faulty. Commonwealth of Australia

34 2. Preparing for work 2.1 Gathering information Before you can begin testing, commissioning and maintaining any hot water temperature control device, you need to obtain the drawings and specifications for the work. You must also gather all other relevant information. This section will examine the types of information you need and where to get it. Information and sources include: requirements of local authorities plans and specifications manufacturer catalogues manufacturer installation requirements Acts, Standards, Regulations and Codes. Authorities Plumbing in Australia is a very regulated industry and it would be very difficult to list all regulatory procedures here. This resource is written as Commission and maintain hot water temperature control devices, and dealings with the individual local water authority belong largely to the business side of plumbing, rather than the practical. Having stated that, however, following are just two examples. Examples Sydney Water The Committee of Uniformity of Plumbing and Drainage Regulations (CUPDR) have released a Hot Water Scald Prevention Commissioning/Maintenance Report for Thermostatic Mixing Valves. You can purchase the report, fill it out, keep a copy for yourself and leave another copy at the premises when you complete a job. 32 Commonwealth of Australia 2015

35 Brisbane City Council Plumbers must complete a Minor necessary works form and submit it to the local council, who then record it in a property file. Plumbers also must complete the necessary maintenance/service report, keep a copy themselves and submit a copy to the person in charge of the premises. As well as local government plumbing authorities, authorities in the health care field may also have specific procedures and/or documentation requirements. Again, too numerous to list check with those in charge of the premises you are working in. Activity 4 Contact your local authority and/or an appropriate person in your workplace to help you identify all the relevant authorities that you will need to consider when undertaking a job. Record their contact details in the space provided. Collect and attach any relevant forms. Commonwealth of Australia

36 Plans and specifications The information generally provided in plans and specifications includes the following: general plumbing design location of mixing valves location of related fixtures location of hot and cold water supplies design flow rate pipe sizes required outlet temperature certification by designer certification by local authority. Manufacturer catalogues Manufacturers booklets are valuable as they provide information such as the following: warranty information product identification operations and performance specifications features and benefits of particular devices contact details installation guidelines accessories such as stainless boxes, bypass valves, binder test points, chrome covers, accessory tapware, etc special repair tools required replacement part identification service guidelines as to time interval between servicing (annual service, five year service etc) and what needs to be done commissioning sheets servicing sheets fault/cause/remedy/diagnosis charts. 34 Commonwealth of Australia 2015

37 Products change so quickly in today s market, a resource such as this cannot provide all manufacturers documents it would be out of date before you even received it! The best way of keeping up to date is to keep in touch with suppliers, attend trade shows, look up information on the Internet, etc. It is up to you to remain informed with what is happening in your industry. Activity 5 Collect six examples of manufacturers catalogues. Add them to your earlier list of authorities, along with other details of information sources you think might be useful (manufacturers, Internet sites, etc). Manufacturer installation requirements Most manufacturers of thermostatic mixing valves have no specific plumbing installation requirements as most are based overseas. That is, they do not specify where the valve goes and how it is to be connected to plumbing. It is up to the plumber and the local authority to determine these details. The manufacturer will, however, specify hydraulic requirements that will be very relevant to a designer/hydraulic consultant. Such information will include: minimum inlet pressures maximum inlet pressures recommended operating pressure inlet pressure ratio maximum static test pressure maximum hot water temperature minimum hot water temperature maximum cold water temperature minimum cold water temperature minimum flow rates. Commonwealth of Australia

38 Tempering valve manufacturers have in the past produced brochures on how to plumb in to assist plumbers on correct installation. There is a copy of such a brochure in every tempering valve box. Acts, standards, regulations and codes The acts, standards, regulations and codes that apply to hot water temperature control devices may vary from state to state. Refer to the appropriate ones for your state. The following are some you should be familiar with. Australian/New Zealand Standard 3500 (AS/NZS 3500) Part 4. Hot Water Supply This standard has information on the installation of valves, the maximum temperatures etc. It has no information on maintenance times and schedules, temperature parameters (high/low), thermal shutdown test procedures. Basically, this Code says, These are the maximum temperatures. It is up to the industry how this happens. Part 1 Cold Water Supply Information only on flow rates and the minimum pressures to supply to fixtures. In most cases, this requirement is already met by the cold water connected to the fixture. Australian Standard 4032 Part 1 Thermostatic mixing valves Materials design and performance This is a Standard for manufacturers ie, if a manufacturer wants to have a valve on the market as a thermostatic mixing valve, it must pass the performance testing requirements of this Standard. You do not need to have a copy of this Standard. Part 2 Tempering valves and end of line temperature activated devices Restrictions on what is on the market are similar to those in Part 1. Again, you do not need a copy of this Standard. 36 Commonwealth of Australia 2015

39 Part 3 Field testing and maintenance This part of the Standard outlines, as it says, testing and maintenance. This may or may not be an empowered document in the area you work in. If AS/NZS 3500 is the empowered document in your local area (as it will be in most cases), it calls up AS 4032 as a referenced document, but it would be a matter of interpretation whether this then empowers AS 4032 or simply refers to it (as the term referenced documents implies). You should obtain a copy of this part of the Standard. Hosplan Code of Practice for Thermostatic Mixing Valves in Health Care Facilities (NSW) This comprehensive Code was written in March As its name implies, it was written for health care in New South Wales, but can be empowered by any hospital board or health authority. The same subject is also addressed in AS/NZS The Code may only be applicable in your work area if the relevant authority or health care board has endorsed it. It would have no application in any building that is not health care. Activity 6 If a job location is a building under renovation, what other specific information might you need? Where would you find this information? Commonwealth of Australia

40 2.2 Determine workplace and equipment safety requirements Is the workplace safe? On arrival at the workplace, your first task is to check safety issues. Are you working in a confined space? Are you working on a ladder? AS/NZS 3500 and local water authorities have for years required all hot water control valves to be readily accessible from at or near ground level. Their aim has not only been a better plumbing system, but also to keep the servicing plumber off ladders and out of confined spaces in the hope of reducing accidents. Nevertheless, there are still many thermostatic mixing valves in very awkward positions that will see the servicing plumber stretching out and crawling through some tight spaces in a building. Is the equipment safe? The whole idea of TMVs is that they are a safety device to prevent scalding, but what of your safety while you are working on these devices? 38 Commonwealth of Australia 2015

41 During servicing, there is a real possibility you will scald yourself with hot water. Remember: many of the systems you will work on operate at above 80 C and in excess of 500 kpa. The probability of an accident may be quite low, but as with any aspect of working in the building industry, you should be ever mindful of what might happen if...? For example, could you be burned if the old TMV located in a crawl space you are working in suddenly blows off the inlet hot pipe? Safety of others The TMV is also designed to ensure the safety of others in the area. For example, if you are working in a health care establishment, you would be well advised to tag the ablutionary fixtures you are working on with Danger Do Not Use signs. You should also inform those in charge of the area that work is about to commence and how long such work might take. It is often an advantage to have two people doing servicing work, particularly when the valve is located some distance from the fixtures. Some plumbers even use two-way radio communication for this task. General safety considerations also apply to tools left lying around, ladders in the way, etc. You must consider others who may not be used to the messiness of many building sites. Remember: all the duty of care rules apply to self and others alike. You may remember the Hot water burns like fire campaign many health authorities ran in the past and, yes, hot water can burn just like fire. The heat energy contained in the water and the way in which water can rapidly cover the skin, results in a quick heat exchange into human flesh in the same way that fire does. How serious is the burns risk? The most common form of injury is a burn, so it is important to maintain correct water temperatures. Thermostatic devices (thermostatic mixing valves, tempering valves and end of line devices) prevent the possibility of someone being burned/scalded by excessively hot water while running water fixtures. If you wonder at what temperature human skin burns, note on the chart below the time/temperature relationship in determining the seriousness of the burn (ie Time/Temperature/Severity). Commonwealth of Australia