PHAM NEWS | DECEMBER/JANUARY 2025 Water Heating& Cylinders 25


The case for smart hot water cylinders in a renewable future


If the some nine million cylinders already installed in UK homes were connected through smart controls and used as heat batteries, the National Grid could unlock 23GWh of energy storage. That’s according to the fi ndings of research commissioned by the Hot Water Association (HWA), explained here by the Association’s technical manager Kevin Lowe.


M


ore and more of our electricity is being generated from renewable


sources, for example by wind or solar. When more electricity is generated than can be used, the National Grid is paying wind farms to switch off , because there isn’t enough room on the grid to accommodate it. Over the last two years, these curtailment payments have amounted to around £1 billion, a cost which is passed on to consumers through their energy bills. As more UK homes move from


gas to electricity for heating and hot water – whether it’s a heat pump, solar PV or electric storage heaters – the only way of achieving quick-fi lling baths or running a typical power shower within the confi nes of our electrical grid is through storing hot water, so the number of hot water cylinders installed will only rise. Fortunately, hot water storage is the best practical solution for turning all the extra energy being generated into something useful – and provide households with cheap, green energy, especially if they also opt for an off -peak time-of-use tariff .


How it works To make this energy storage potential a reality, existing hot water cylinders will need to be fi tted with smart controls or replaced with new, smart models, whether they are part of a gas boiler or heat pump heating system. The smart device would be in contact with the electricity grid and automatically activate to heat the cylinder when there is excess power. This is known as Demand Side Response (DSR). DSR fl attens out the peaks


Kevin Lowe Technical manager of the Hot Water Association


Heating


engineers are key because they are going into


people’s homes to install their cylinders


and troughs of the electrical landscape. It fi lls in the troughs when demand is low, and irons out the peaks because the demand has already been satisfi ed. Reducing peak demand reduces carbon emissions because a higher proportion of the energy mix is achieved from renewables and other non-carbon options.


Make the connection There are a number of ways that a hot water cylinder can be connected. • The heating appliance will


have some form of connected smart control within that will communicate with the cylinder, controlling the heat input.


• The cylinder itself will


have an embedded Wi- Fi module which enables connectivity. This can also provide intelligent heating through scheduling, machine learning and dynamic tariff optimisation. • A connected plug or smart


switch can be installed on the switchboard, so the hot water cylinder can be turned on and off remotely. • A smart thermostat can


be retrofi tted, plugging directly into the cylinder’s controls. Typically, this would be combined with sensors either inside or outside the cylinder to measure pipe/fl ow temperatures.


In control Most of these types of controls allow the householder to control their hot water schedule remotely with an app. Some also provide insights into energy consumption while some allow external third parties to turn them on and off . Heating engineers are key,


because they are going into people’s homes to install or maintain their cylinders and heating systems. They can help to educate their customers, so they understand the benefi ts that thermal storage can off er them, and explain why they should not get rid of a cylinder. In addition, if grants or other fi nancial incentives


 How hot water cylinders can provide fl exibility to heat in times of excess supply of renewable energy


CONNECTED HOMES


 Hot water storage is the best practical solution for turning excess renewable energy into something useful – and provide households with cheap, green energy


were available, this could promote the installation of more cylinders. We would also welcome an uplift in SAP and EPC ratings for properties with smart controls. If we are to achieve up to


40GWh of energy storage that our research predicts could be achievable with a 36% increase of installed cylinders, it is vital that industry organisations, government, manufacturers, regulatory bodies, and installers all work together.


Download a copy of the HWA report


Connected Homes


CONNECTED CYLINDER REPORT / 1


To fi nd out more about thermal storage, the full report can be found using the reader link below. ◼ phamnews.co.uk/125/15


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