David White of Mixergy explains why housing associations and landlords should consider installing intelligent hot water tanks, detailing the vast array of benefits they can bring both landlords and tenants

We now live in a world where macro industry themes creep into all aspects of modern life. The rise in the adoption of renewable technologies being used to generate electricity for the grid and for the home is now affecting everything from the price of electricity to the need for distributed storage devices being promoted within the home. The interaction between grid and home leads to a greater need for inter-connectivity, so the Internet of Things (IoT) becomes increasingly relevant. The rise in IoT devices creates access to more data, such as smart thermostats that can tell whether a tenant lives in a damp home or if they are even in! Knitting these together can create a sustainable eco-system of technologies that helps the national grid use renewable energy, tenants save energy (and money!), and housing associations take a more informed view as to the hygiene and performance of their estate.

Limitations of conventional tanks

Many homes across the UK have stored hot water systems as opposed to directly heated hot water by a combi-boiler. This is beneficial to homeowners as they can have hot water available throughout the day and heat it using a boiler or by direct electric, often using economy 7/10 tariffs. Combi-boilers aren’t suitable for all homes as some apartment blocks are electric only and some homes are too large for a combi-boiler, where hot water needs to feed more than one bathroom concurrently. So, for those with hot water cylinders in their homes, access to new innovations and opportunities to help them save energy and money have been limited. The main innovation in hot water cylinder design in the last 30 years has been a move from copper to stainless steel, improved insulation performance and to install expansion vessels within the cylinder, rather than externally – and that innovation only serves the installer as it speeds the job up! Conventional hot water cylinders behave like kettles, heating all or nothing. When the hot water is used they allow cold water into the cylinder while the hot water is present, diluting the hot water store. This means that the water has to be reheated again. Conventional hot water cylinders also have hygiene concerns as they can only heat to the bottom of the lowest heat exchanger, meaning there is a grey area at the bottom of every cylinder that is at risk of growing water-born bacteria. And finally, there is no way of knowing how much hot water is inside, leaving householders playing shower roulette or unnecessarily boosting the tank with its immersion heater.

The opportunity

The advent of the IoT, computational fluid dynamics in design and advanced software development and micro-electronics has facilitated a step-change in the way in which hot-water storage can be viewed as a solution. The deployment of a smart hot water cylinder can now provide compelling benefits to the full value chain from grid to occupant. Smart sensors and controls now offer occupants visibility of how much hot water they have, the ability to schedule which heat-source to use and opportunity to only heat what is needed, rather than what is allowed. If you live in a three-bed house and no showers are run that day, you will have heated the full volume of the cylinder just to serve your hand and dishwashing needs. Selectively heating known volumes of water within the cylinder ensures that occupants are in control of how much energy they wish to invest in hot water and empowers them to reduce their hot water bills as much as possible. Taking the idea of dynaminc volumetric storage even further, smart machine learning algorithms can aid tenants in their search for energy cost reductions, ensuring hot water is always available but never more than is required.

The solution

All of the above is achievable using a smart hot water cylinder, such as Mixergy’s, that exploits thermal stratification to revolutionise how cylinders behave. How does this benefit the registered provider? Empowering tenants to reduce their hot water bills by up to 40 per cent is a great way of contributing to the association’s fuel poverty strategy. There are also some new previously inaccessible data sets and insights made available. Having smart networked tanks, visibility of the usage and hot water temperature performance within the tank now enables housing associations to have an auditable water hygiene strategy. Is it at a safe temperature? Has it been pasteurised recently? Is my tenant using hot water at all? The smart technology deployed on the Mixergy smart hot water tank has allowed some really interesting data insights to be gathered. When given the opportunity to selectively heat a cylinder by volume (i.e. 1-100 per cent) the average state of charge of over 400 networked tanks was shown to be only 60 per cent, showing that over 400 customers are no longer needing to heat the full volume to serve their hot water needs. Volumetric control with a smart schedule has delivered up to £124 per annum in hot water bill savings for some users. This is made easy for tenants with a smartphone app, a desktop login and simple visual gauge or even a remote control, ensuring that even the most technophobic can still benefit from the technology. Data has also shown that there is less than 5 per cent probability of an occupant using more than 60 per cent of a hot water tank in one event – and these rare events can be boosted and planned for rather than the ‘just in case’ daily full charge only offered by conventional cylinders. Measurement and control of the cylinders water temperature from top to bottom also provides new opportunities. The Mixergy cylinder, for example, uses a pump to drive the hot water thermocline to accurately control water volume to an accuracy of 1 per cent, and it can also drive hot water to the absolute bottom of the cylinder. This ensures that complete pasteurisation of the cylinder takes place. Pasteurisation events are controlled by the tank, as is the stored water temperature. This ensures that cleansing cycles are carried out at suitable intervals, proactively managing the health of the domestic hot water system. This data is provided to housing providers in a smart intuitive dashboard. Additional savings are also achievable now cylinders behave like a hybrid, enabling control of each available heat source. For example it can be set to use electricity between 3 am to 9 am, solar between 9 am to 4 pm and gas between 4pm to 3 am, meaning that occupants can reduce bills as much as possible by using whichever energy source is cheapest or most prevalent at any given time. Sensor networks on smart cylinders like Mixergy’s allow remote diagnostics and maintenance to be carried out, reducing the number of field service visits required and improving the first time fix rate. Reheat recovery times are improved when charging the tank volumetrically – reheating up to five times faster than conventional cylinders through use of its diffusers that prevent hot and cold water mixing. This means that housing associations can now install cylinders that are 30 per cent smaller than the one they replace, making more room for storage in their tenants homes. The opportunity to meet the demands of macro themes upon our organisations while offering tenants a better user experience and lowering their costs is a challenge, but smart deployment of the right technologies can make this easier. One simple lifecycle replacement that doesn’t require an additional infrastructure and can improve the asset management and maintenance strategy of the housing provider and effectively manage an estates fuel poverty and water hygiene is now in possible with the use of intelligent hot water cylinders.

David White is business development manager at Mixergy

Housing Management & Maintenance (HMM). 2019. Mixergy Ltd.
Available at: https://www.housingmmonline.co.uk/companies/mixergy/