CPD How is precise temperature control achieved? Temperature control is the procedure where the change of temperature of a space or substance is measured and the movement of heat energy into or out of said space or substance is adjusted to achieve a desired set temperature. In the case of hot water heaters, this process is governed by a temperature controller. This instrument simply calculates the difference between a set-point and a measured temperature by taking an input from a sensor and giving an output signal for the connected heat element. Venturing into system design, another way to ensure the desired temperature is provided at the outlet is by using thermostatic mixing valves (TMVs). A TMV uses an internal thermostat that blends hot and cold water to achieve this result. s s s ,IMITLESS SUPPLY OF HOT WATER PROVIDED constant gas and water connections exist. ,IGHTER AND REQUIRE LESS SPACE !DVANCED MODELS CAN SUPPLY VERY precise temperature accurate hot water. Table 1 opposite shows a comparative analysis between a continuous ow and storage water heater. As you can see from the data, the storage tank option tends to be less efcient and consume more energy. Once you factor in replacement costs, a continuous ow hot water heater is the more cost and energy efcient option as well as being better at reducing the carbon footprint. However the most important feature with regards to temperature control and what makes continuous ow the preferred option for this application is the ability of some continuous ow water heater models to constantly provide temperature accurate hot water with a precision of up to 1C. Temperature control in practise Legionella & ACOP L8 Hot Water Delivery units and systems For more details on RINNAI products visit www.rinnaiuk.com The two main forms of supplying hot water are the conventional storage tank water heater and the continuous ow (instantaneous) water heater. The main differences are outlined below. Storage water heaters: s (AVE A LIMITED AMOUNT STORE OF WATER s 7HEN STORE DEPLETED TAKES TIME FUEL to reheat before use. s 2EQUIRE GREATER PLANT ROOM SPACE s -ATERIALS HANDLING ISSUES HEAVY and cumbersome. s 3TANDING LOSSES Continuous ow heaters: s (OT WATER IS HEATED AND PROVIDED solely upon demand. s %VIDENCE AND DATA THAT THEY ARE mechanically and operationally more efcient. !#/0 , IS THE (EALTH AND 3AFETY Executive Approved Code of Practise that GOVERNS THE CONTROL OF ,EGIONELLA IN WATER SYSTEMS ,EGIONELLA n FULL NAME ,EGIONELLA pneumophila is a bacteria that causes, amongst other less serious conditions, ,EGIONNAIRES DISEASE A POTENTIALLY FATAL FORM OF PNEUMONIA ,EGIONELLA BACTERIA ARE common in natural water sources but the conditions are rarely conducive to people catching the disease. This usually occurs in purpose-built water systems and the risk OF BEING EXPOSED TO ,EGIONELLA INCREASES IN warm, stagnant water, passed to humans via breathing in miniscule, aerosol-like droplets of water. Specic guidance for the CONTROL OF , PNEUMOPHILA IN WATER SYSTEMS IS PROVIDED IN !#/0, AND ITS ASSOCIATED regulations, HSG274 Part 2. 7HEN IT COMES TO COMBATING ,EGIONELLA precise temperature control is one of the strongest weapons available. The bacteria begins to die in temperatures above 50C and cannot survive above 60C Certain conditions support the growth of bacteria, such as a temperature range of 25C to 45C as well as the presence of certain deposits such as lime-scale, rust, sludge 26 September 2020 www.cibsejournal.com Advertisement Feature p25-28.CIBSEMagSept20.indd 26 17/08/2020 15:07