Experimental study on the energy assessment of CombiSave device for hot water control

Every household uses an average of around 360 litres of water each day. About 21% of a typical gas consumption is attributed to heating the water for showers, baths, and hot water from the tap. An environmentally friendly, low-cost device called the CombiSave valve can be used to manage gas and water consumption and should be fitted to most combination boilers to automatically control the flow of water every time a hot tap is turned on. This allows the boiler to heat the water faster and only return the flow to normal once a usable temperature is reached. An experimental test was conducted in the exemplar modern house of Liverpool John Moores University in order to assess the amount of water, energy, and CO2 reduction for varying temperatures and flow rates. The test was carried out for a duration of 9 hours during the daytime between June and October. Although the test was conducted over relatively warm months when ambient water temperatures were higher compared to winter months, results showed that good savings could be achieved through this product. The best savings for gas consumption and hence CO2 reduction were achieved at high water pressure and low temperature setting (40 ℃) of 36% compared with the case without combiSave. While water consumption was reduced by 56% at full flow rate and 45 ℃. Further research is needed encompassing multiple occupied dwellings with different family sizes and testing these in extreme weather conditions to see if similar results would be reflected.