CPD For more details on RINNAI products visit the infection control risk (Owen, 2020). With causes ranging from incontinence to open wounds, clothes, towels, linen and other types of fabric may come into contact with all manner of bodily uids, purely due to the nature of the industry and so it is imperative that when it comes to handling soiled laundry, not only is all contaminated linen managed and separated appropriately but thermal disinfection is properly implemented. In essence, thermal disinfection is the use of above average wash temperature for a set cycle time to ensure any potentially infectious microbes, such as blood-borne pathogens (HIV, Hepatitis) or Clostridium difcile, are killed. These bacteria, as well as the likes of Staphylococcus aureus - a well-known pathogen that if allowed to invade the skin deeply can cause a plethora of diseases, ranging from supercial skin infections that cause boils to more systematic issues like pneumonia and blood infections - can survive temperatures of over 50C degrees and so using wash cycles that are not only hot enough but long enough to destroy the potentially infectious bacteria is important. As stated in a 2019 paper by Bockmuhl et al, temperatures of above 60C are known to inactivate organisms and insure a high level of hygiene in laundry (Bockmuhl, Schages, & Rehberg, 2019). With this in mind it is important the washing process is tested and veried. One way of doing this is by using a swatch of fabric with a certain amount of the bacteria in question on it, placing it in the washing machine and going through a typical wash cycle. After the cycle, you would measure the bacteria left to see if it has been effective, which is conveyed by a microbial log reduction. This is a mathematical scale that displays how successful a product is at reducing pathogens the greater the log reduction, the more effective the product is at killing bacteria. In this case you would look for at least a 5 log reduction. (Bockmuhl, Schages, & Rehberg, 2019) Log, short for logarithm, is a mathematical term for a power to which a number can be raised. For example, if using 10 as a given number, a Log 3 increase can be shown as 103 or 10 x 10 x 10 = 1,000. A log reduction takes the power in the opposite direction. For example, a log reduction of 1 is equivalent to a 10-fold reduction or, to put it another way, moving down one decimal place or a 90% reduction. In micro-biology, a colony forming unit (CFU) is a unit used to estimate the number of viable bacteria in a sample. The number of CFUs present would be counted before and recounted 78 www.rinnaiuk.com November 2020 www.cibsejournal.com after the cycle and the resultant difference would be declared as the log reduction. For example, if the number of CFUs beforehand was found to be 10,000,000 (107) and the end result was 100 (102) then as it is 100,000 times smaller, that would be log reduction of 5 or 99.999%. Effect on energy consumption Temperature not only plays a key role in disinfection but also in saving energy. As mentioned before, the washing machines heat up the incoming water to the required temperature. This consumes energy and so the smaller the difference between the incoming and required temperature, the lower the consumption as it would take less time. In the realm of laundry, time dictates capacity. This means that the longer the cycle takes, the less loads you can wash in a set time period. This ultimately leads to investing in more machines. The reverse is also true in that you can reduce the amount of washing machines needed by reducing the total time of a wash cycle and the variable part that can be reduced is the time needed to heat up the water. For example, imagine a scenario where you had 2 loads to wash, a 90min window in which to do it in and each cycle took 60mins. You would need to have 2 machines. If the total cycle time could be reduced to 45mins, then 1 machine would sufce, not only ensuring savings in consumption but cost as well. Veried Additionally, if the water heater connected to the machine is more efcient, this further reduces overall consumption. This next part of this paper will explore two of the mains ways to supply washing machines with hot water - instantaneous continuous ow water heaters piped directly into the washing machines and having the washing machines connected to conventional storage water heaters. Options Storage tank options tends to be less efcient and co nsume more energy. Once you factor in costs of replacement, it is clear that a continuous ow heater is the more cost and energy efcient option as well as being better at reducing the carbon footprint. Due to their ability to modulate, continuous ow heaters only provide an output in response to the water ow and temperature demand. This means that depending on what is required, the KW rating can range anywhere from a given maximum output to a minimum. However, Advertisement Feature p77-80.CIBSEMagNov20.indd 78 20/10/2020 13:03