Go with the flow28 September 2020
Achieving accurate and consistent temperature control for cost effective laundry disinfection for elimination of Covid-19 and other pathogens needn’t be a pipe dream, says Chris Goggin, who explains how a continuous flow water heater setup could be the solution.
Living in the new ‘normal’ is making all of us adjust and radically change our approach, our thinking and our application to all of our previous ideas, although we still have to operate in producing an end product. Let’s now explore how hot water technologies can assist in producing laundry that achieves the highest levels of hygiene.
We are still amid Covid-19 and its tragic dividend, with daily notices of infection rates around the world and snap news items about the latest virus repercussions that could wreak havoc. But we must stay focused on reducing its impact and that of other harmful bacteria to as close to zero as possible.
In late March we at Rinnau UK decided to respond, not react. This meant that we changed our entire operation to focus on serving essential works with 24-hour availability of service - both technical and operational. Our response made a difference to our customers as it allowed them to operate secure in the knowledge that their hot water supply was, provided they are connected to gas and water, truly limitless and on-demand. The laundry industry is of course one of those essential industries, mostly unsung, that is utterly vital to our everyday functioning.
Laundry businesses by their very nature must yield a product that is free from any harmful bacteria. And continuous flow (also called tank less) hot water heating systems with temperature control and adjustments can be an integral part of the process of thermal disinfection in onpremises laundries, in care-homes and hotels, high street commercial laundries and commercial laundries using large, washer-extractors.It is also worth noting that no operator wants to be eaiting on water to ehat up in the applince which is costly in terms of both money and time.
Now, when the need for cleanliness is paramount, and very much to the front of public awareness, we must reconsider the design of laundries’ hot water services to not only incorporate heat engines that provide copious volumes of hot water but also, crucially, provide that hot water at the precise temperature needed. This sound guidance can be seen within the UK Dept of Health’s guidance note - HSG(95)18 ‘Hospital Laundry Arrangements for Used and Infected Linen’ - which states: “The washing process should have a disinfection cycle in which the temperature in the load is maintained at 65C (150F) for not less than 10 minutes or, preferably, at 71C (160F) for not less than three minutes”. However, this guidance on achieving purely thermal disinfection is now being complemented by modern systems which use thermo-chemical disinfection at lower temperatures (turn to page 22 to see the latest developments in chemicals that aim to achieve this) and some of these also deal with Covid-19. However, the importance of accurate and consistent temperature control is still as vital as ever and this is the responsibility of the launderer.
In the design process pre-Covid-19, consideration was often concentrated on the volume of water required. But now Covid-19 means that designers and consultants would be advised to closely consider the temperature of the hot water services relevant to the specific laundry application.
The benefits of temperature control are not new – for example, in the world of building services it is well understood particularly, for anti-legionella regimes (see box). With ACOP L8 advising that “maintaining a supply temperature of at least 60C from the heat source and/ or storage vessel (calorifier)” among other system design advice. All hot water delivery systems in any commercial or institutional sites need to be given detailed consideration to the potential of Legionella proliferation during the shutdown. This will necessitate that certain procedures and measures are carried out before the system can be made ‘live’ and function efficiently.
ACOP L8 guidelines, produced and published by the Health & Safety Executive, lists the details and necessary procedures to ensure system cleanliness. According to ACOP L8, continuous flow direct to outlet systems are low risk for Legionella, due to it allowing for a full turn-over of water volume, no stored water and accurate temperature control.
There is also greater scope being given to the importance of temperature in terms of building efficiency and carbon footprint. There are already industry groups lobbying with growing influence – refer to ‘Taking the temperature – domestic hot water’, CIBSE Journal January 2020 online https:// www.cibsejournal.com/technical/takingthe- temperature/. This is directed at domestic installations, but is still relevant.
From almost all angles this is rightly so, as the necessity to design hot water systems at a set point greater than needed to satisfy Legionella concerns or temperature loss fears or to build in shunt pumps to continually pump water round an unoccupied building to prevent stratification, raises the real question“ Are we using the right system for the job?”
Temperature plays a critical role in minimising as close to zero as possible the proliferation of bacteria in laundries. But it is the use of temperature accuracy, used to its full potential, that can greatly benefit the laundry industry – including the end-user, who expects clean laundry to be disinfected and free of risk from Covid-19.
Systems often used in the laundry process will incorporate stores of water and electric immersion heating elements to keep that water store near temperature. These systems inherently will suffer from long reheat periods, stratification, and increased potential to provide hot water at inadequate temperatures. The frequency of use within hotel and care-home laundries can often outpace the system capabilities to heat water to the desired temperature, highlighted above in HSG (95)18, meaning harmful bacteria harboured in linen could survive the laundry process.
Parallels regarding risk should now be drawn between harmful bacteria, in a post-Covid-19 (or ‘new normal’) world in equal measure to the reduction of all harmful bacteria, and not just those that are water borne, should be given major consideration at the design stage.
Consider the system below that uses temperature accurate heat engines or continuous flow water heaters.
This particular system will provide temperature accurate hot water at a preset of 70C, 72C and 75C. The performance is well suited to commercial applications, with first hour flow rates of more than 4500 litres, continuous flow rates of over 4100 litres and a recovery time of eight minutes.
This enables demand to be met with the consistent temperature accuracy. In the event that demand exceeds design capacity, the flowrate is automatically reduced, rather than allowing temperature error. The system is also scalable for any sized laundry application, with the additional feature of in-built redundancy and advanced telemetry to ensure temperature accurate hot water is consistently available. This is one of the essential features in your assurance to the laundry end-user.
In February 2019 BSI, the business standards company, released British Standard BS 8580-1:2019 Water quality, risk assessments for Legionella control – Code of Practice. This was a significant revision to the 2010 British Standard providing further guidelines for assessing water quality and the risk of Legionnaires disease.
The standard gives recommendations and guidance on the assessment of the risk of Legionellosis presented by artificial water systems. Legionellosis is a collective term for diseases caused by bacteria of the genus Legionella, an opportunist pathogen which normally inhabits warm, moist or aquatic environments. The most serious and potentially fatal is Legionnaires’ disease.
To learn more, please visit: www.bsigroup.com
LCNi caught up with the owner of M Saul Electrical, specialist in commercial laundry and pumping solutions. Michael Saul, who is well known in the industry having been behind many a successful laundry design and installation.
“I have been using Rinnai now in laundry installations for getting on for three years and must have installed 30 in that time and have never had to get back to one yet. They are brilliant.” He says he had been using another brand and was always having trouble with them. efore he discovered Rinnai. “I was glad when I didn’t have to use them any more,” he says.
Saul was introduced to Rinnai technology by a contact who said: “Use Rinnai. They are dead simple and efficient”.
“HM Prison Liverpool (formerly Walton Gaol) laundry was my first job using Rinnai. They needed a mix of gas and steam for the hot water system and we put four in there and then I installed six at Wealstun Prison laundry, Wetherby and then I was putting them in for laundries using washer extractors all over the place.”
The units don’t have to be used as continuous flow, he adds, in many cases he prefers a pressure system and to store the hot water in a tank offering 1000 litre storage capacity. “If it is really well insulated that is fine,” he adds.
“I have just put two Rinnai units into a private laundry in Newcastle that is servicing the NHS and in another private laundry in Essex that is also doing NHS work. In Newcastle, on another job, I put up two up on the framework and left room to add another one if needed at some time in the future. I like that about them – they can be manifolded many times.”