The Conflict: Legionella or Burns?

Not much of a choice, but this conflict is at the heart of every plumbing system. Water heated and stored at sufficiently high temperatures to control and kill bacteria such as legionella, but it can also cause severe scalding injuries in a matter of seconds. If water is heated and stored at safe non-scalding temperatures, this provides the ideal medium and temperatures for bacteria growth.

Legionnaire’s Disease

Legionnaire’s Disease comes from a naturally occurring organism that can be found in low levels in the water supply. It is a bacterial disease that is contracted from small droplets of water that are contaminated with legionella bacteria and which have become suspended in the air and may cause pneumonia. The time from infection to start of the illness (the incubation period), is between 2-10 days and the disease can be particularly deadly to the very young or old, especially if infirm.

Aerosol droplets that allow transmission of legionella are found in: whirlpool spas, showers, cooling towers, taps with sprays etc. Legionella can grow in any water system that is not properly maintained.

Elimination of legionella from a system

Methods to eliminate legionella include chlorination. This method of treatment is used when a system is cleaned prior to commissioning and has real disadvantages if a system is being used. Another option is to use heat treatment (i.e. running water above 70°C for 30 minutes in the whole sanitary system), though this can also have serious drawbacks if no temperature control is used on the outlets.

If temperature control down to a completely safe level is exercised at the water heater (i.e. turning the cylinder down to a non-scalding temperature so that all the stored water is below 50ºc), the following will occur:

  • The system will not comply with building regulations,
  • Water usage will increase as users run taps for longer periods, in the hope of getting hot water,
  • Users will not get a hot bath unless the water heater is close to the bath because of the temperature loss from the pipework between the water heater and the point of use,
  • Washing up becomes a problem as lukewarm water will not shift grease.

Building regulations state that the circulation of hot water must be at temperatures sufficiently high to stop the legionella that naturally occurs in the water supply from multiplying to a level that will cause health problems to susceptible people. In the UK building regulations stipulate that hot water should be stored at no less than 60ºC and circulated at no less than 55ºC to prevent the growth of legionella.

The Burns Issue

Every year 23 people are killed by being immersed in hot water by mistake by a carer or nurse or by falling in to a bath and not being able to get out quickly enough. These are sobering statistics when you consider that the burns suffered by scald victims are every bit as painful and destructive as those suffered by victims of fires or explosions.

Almost 90% of the 570 people who suffer serious scalds each year, which require hospitalisation, are children. Other groups considered to be at high risk are the elderly and disabled. While children are normally scalded because they do not identify or understand the risk, the elderly and disabled are more likely to be injured or killed as a result of not being physically able to remove themselves from the scalding situation when they find themselves in danger.

A typical scenario is a carer or nurse filling a bath of hot water and leaving the person to get in by themselves; quite often the bather will sit on the side of the bath and swing their legs over and into the water. At 60 degrees an adult will suffer third degree burns after less than six seconds of immersion, with an elderly person this time is likely to be even less due to the more sensitive nature and reduced thickness of their skin. Regardless of skin sensitivity, however, it is clear that anyone who is even marginally impeded in their movements is going to suffer a serious scald injury at such temperatures. 90% of all people who are killed each year by scalding are the elderly aged 65 and over.

Legionella or Burns? The Solution

Water below 50°C can be considered ‘safe’ as even for a child to receive a second degree burn it would take 45 seconds, however water stored below 50°C creates a breeding ground for legionella bacteria to breed.

The best solution to both problems is to fit a thermostatic mixing valve at the point of use (i.e. local to the taps). This will allow the hot water to be stored at a sufficiently high temperature in the water heater to prevent bacteria growth but the TMV will mix cold water and hot together and discharge it out of the tap at a controlled and stable temperature, typically 38-44°C in a hospital or nursing home, to prevent scalding the end user.

I addition, Reliance UK also offer an ‘Anti-Legionella Valve’ designed to convert a standard single connection expansion vessel into a ‘flow through’ type so water is continually renewed to prevent water stagnation & bacteria growth.

TIU - Thermal Interface Unit
What is a Thermal Interface Unit (TIU)?

TIUs form part of a Community Heating Network (CHN) that provides central heating and domestic hot water to individual properties or apartments within a single development.

Traditionally in the UK, housing stocks have been built with individual gas combi boilers located in each apartment. Conversely, across mainland Europe Community Heating Networks – (or District Heating Systems as they were previously known), have long been the solution to provide heating and hot water in large community developments, with a centralised energy centre coupled with a low temperature hot water network.

In recent years we have seen a resurgence of CHN developments in the UK as the available technology improves and becomes more popular in helping comply with current legislation for energy efficiency and reduced emissions. Community heating networks operate from a single energy source (the energy centre) that distributes energy in the form of hot water circulating within a primary network throughout a building or housing development. Each individual house or apartment has a secondary network which is connected to the primary network via a thermal interface unit that heats DHW and space heating water via plate heat exchangers to meet the individual demands of the property.

The Radiance TIU range from Reliance UK offer the perfect solution as they can be adapted to exact requirements when an instantaneous or stored hot water system is required in a Community Heating Network installation.

As a leading supplier to the UK heating industry for many years, we have gained a wealth of knowledge and experience in the design and production of innovative products. The RWC brand is recognised for quality and reliability and our TIUs, created specifically to suit UK systems, have been designed, manufactured and tested to ensure they provide the same high levels of satisfaction and longevity.

We understand that no two project requirements are the same, that is why we provide a dedicated technical and design support service to work alongside you. This enables us to develop custom-built solutions to meet the exacting needs of your project. We won’t just focus on the TIUs, we will ensure your whole system operates as effectively and efficiently as possible to meet every demand.

Our Radiance TIUs are manufactured in the UK ensuring lead times are minimal and deliveries can be made to suit a site’s requirements.

High efficiency solution for community heating networks

  • No requirement for gas throughout the building avoids the cost of testing/regulations for installing gas
  • No requirement for flues saves cost and allows for an aesthetically pleasing building exterior
  • No planning constraints
  • Simple design; reduced maintenance
  • Easily integrated with renewable heat sources if desired (CHP, biomass, heat pump, solar)
  • Ultra-safe well-known technology using only low pressure hot water
  • Individual metering options available, including automatic meter reading or a prepayment meter

Are you looking for a Thermal Interface Unit for your project? Use the form provided below and we can help find the perfect solution to meet your needs.

Why choose Timeflow Washroom Solutions?

Today Britain’s reservoirs are threatened by an ever-increasing demand for water. Risks of shortages and pollution caused by excessive use of water are well documented not only in the UK but in many other parts of the world as well. Wastage can account for almost 20% of total water consumption.

To preserve the future of Britain’s water reserves, water must be managed in an economical and ecologically sound way. Reliance UK has a long history of providing high quality products to meet the changing demands of the marketplace and our range of timeflow valves are the ideal solution for water saving and water control devices. Listed on the Water Technology List, Reliance UK products are also WRAS approved and comply to BSEN816 and BREEAM.


Water Savings Explained

Because of the dwindling natural resources and the high cost of water and waste treatment, it is now clearer than ever that we must change our usage habits in terms of water control. But how much water can a timeflow control really save?

Consider the following example. If we assume that the average person will spend 1 minute washing their hands in a public facility, with an unregulated tap running at 15 litres per minute, that person would use 15 litres of water.

If a timeflow tap was fitted, the person would wet their hands and start soaping during the first run time of 15 seconds, finish soaping without water running and then rinse off during the second run time of 15 seconds. With the internal flow regulator set at 6 litres per minute, in this hand washing scenario the person will have used a maximum of 3 litres. A third or fourth activation would still use considerably less water than the unregulated manual tap.


Flow Regulation

In order to minimise waste and to realise the best possible benefits from the use of timeflow taps, it is important that not only the duration of the flow be controlled but also the rate at which the water is flowing. Most taps in the Reliance timeflow range incorporate an adjustable flow regulator; this comes factory set at 6 lpm (at 3bar) but can be adjusted to give a flow of between 4 and 10 lpm. In addition to this a flow regulator is fitted which is also set to 6 lpm but can be removed if a greater flow is desired.


Anti-vandal = Anti-waste

In addition to the substantial savings that can be realised by something as simple as automatically regulating flow as these taps do, there are also substantial savings to be made from the fact that the valves are vandal resistant.

A common occurrence in commercial properties of all types is for taps to be left running, either by accident or design; sometimes a vandal may also block the drain for added fun and destruction. With a typical manual tap this is done by simply leaving it on. With a timeflow tap the button or handle has to be blocked open or tied with wire or string – more difficult but not impossible.



Two critical considerations when selecting timeflow taps for use in the commercial arena are the speed and ease of maintenance of the products. All of the Reliance timeflow taps are built using a one-piece cartridge principle; this means that only one part needs to be stocked to completely refurbish the inner workings of the tap. This can save an enormous amount of time when servicing the taps as well as simplifying the stocking of spare components.


Timeflow Basin and Bib Taps

The Reliance range of timeflow taps are an ideal solution to control and regulate the use of water for ablutionary purposes in commercial, industrial, and leisure applications and can be used in conjunction with Reliance’s range of thermostatic mixing valves to give a complete temperature and flow control solution.

Timeflow taps have been shown to save up to 60% of the water usage of a conventional tap by automatically shutting off the flow of water after 15 seconds. The cartridge style construction of these taps reduces parts stocking and means that maintenance downtime is kept to a minimum.


If you’d like to find out more about Reliance Timeflow Products you can visit our Washroom Solutions product page or drop us a message using the below contact form.