Thermal stores - The ideal solution for housing providers

by Jason Hobson, Divisional Director, McDonald Water Storage

Thermal Stores have been an effective and highly efficient hot water solution in the UK for almost 40 years. However, many installers today revert to an unvented cylinder solution for mains pressure hot water, mainly due to a lack of awareness and understanding of thermal store technology.

McDonald Water Storage have seen thermal store popularity rise however, particularly in apartment applications, as they overcome many of the frustrations both installers and housing providers have with unvented cylinder installations, including the hidden costs of the difficult G3 requirements and ongoing annual maintenance.

So, why are housing providers looking at utilising thermal stores to simplify the installation process and improve the finished solution with a fit and forget hot water thermal store?

In many instances it is out of necessity, for example in projects where apartments existing traditional vented or combination cylinders are upgraded to mains pressure hot water solutions. In older developments, the original cylinders tend to be open vented and only required an overflow at the time of installation. However, the discharge requirement for an unvented cylinder requires a continuous fall of at least 1 in 200 to comply with G3 of the building regulations, adding cost and time to the installation and ultimately a requirement for screeding the pipework under the floor to allow the necessary fall. In addition to this, due to high temperatures, there is a requirement to discharge to either a metal or high temperature soil stack capable of withstanding 90 degree water. With many multiple occupancy schemes having older lower temperature stacks, this becomes a real challenge.

Other times it is simply the best solution for the project. For instance, when the cylinder needs to be located where the space is restricted, the CUBEflow thermal store provides the perfect solution, as it requires 27% less space than a standard cylinder due to its rectangular tank design.
From a health and safety perspective, the benefit of a legionella free and scald protected system, protects residents in years to come. Thermal stores provide a fit and forget solution, with reduced installation complexity and require no costly annual maintenance.

Turning the traditional approach on its head
With a thermal store, the traditional approach to generating hot water is reversed.

Instead of storing hot water in the cylinder under pressure, which is then used for taps and showers when required, the thermal store acts more like a battery storing the energy from any fuel source when it is cost effective, and then providing hot water and heating when it is needed in an inherently safe vented store.  

The mains pressure hot water is generated by passing the mains pressure cold water through the highly efficient internal coil, and the heating by sending the stored water around underfloor or radiator system.

Thermal store diversity
We are all aware how energy can be generated in a property and stored in a battery through PV panels or when low-cost electricity tariffs are available, for use by the household when required to power electrical products.

The thermal store works on the same principal and recognised as the optimal solution for incorporating renewable energy inputs. This is highlighted in the THERMflow multifuel products, providing the ability to harness the energy from multiple heat sources as it is generated, just like a battery and store it until it is required and then transfer the heat into heating and hot water on demand.

Thermal stores, such as the ELECTRAflow and ELECTRAstore, are utilising the electricity not just as a backup, but as an important heat source to enable the load shifting of energy demand. This provides a fantastic opportunity in apartments as electrification is required, enabling the costs to be competitive with that of a traditional gas system, with the added benefit of carbon reduction.

Central plant benefits
The HWA (Hot Water Association) reinforced the message regards the benefits of using hot water storage within heat network schemes whether central plant or district heating, with their publication Design Guide for Stored Hot Water Solutions in Heat Networks.

Having localised storage means that the boiler size and therefore pipework infrastructure can be dramatically reduced in, saving money, and building the efficiency of the system by smoothing out the running load of the boiler. The thermal store provides the perfect option to old heat interface units commonly installed in conjunction with central plant boilers.

A thermal store which is specially designed for central plant applications, will incorporate an immersion heater to heat the complete store, enabling the central plant system to be turned off in summer months when heating is not required or for routine maintenance.

For more information and more tips on the use and application of thermal stores visit the McDonald Water Storage website