Case Studies

Khota Stone Limited

  • Client

    Khota Stone Limited
  • Location

    Khota Stone Showrooms, Preston, Lancashire
  • Sector

  • Requirements

    To provide heating solutions for the ground floor showroom, and the first floor storeroom and offices at Khota store. To supply hot water for two WC's and the kitchen.
  • Objective

    To install a bespoke, energy efficient heating system, allowing Khotah Stone to have total control of all building zones, and at the same time, minimising costs. To install a separate hot water supply to the building without compromising the efficiency of the Air Source Heat Pump (ASHP).

In need of an energy efficient heating system to provide heat and hot water to its new showroom at Roman Stone Samlesbury in Preston, Khotah Stone Limited approached SC Horsfield Building Services Engineers Limited, following an extensive search on the Microgeneration Certification Scheme (MCS) website.

The Microgeneration Certification Scheme was launched in 2008 and is an industry-led quality assurance scheme. It has since become nationally recognised and is supported by the Department for Business, Energy and Industrial Strategy.

MCS certifies installation companiesto ensure that all microgeneration products have been installed to the highest possible standard for the consumer. For more information visit

The new showroom required an energy efficient system which would reduce the CO2 emissions and keep energy bills as low as possible. The installation would also need to qualify for MCS approval, meaning any equipment would have to be on the Energy Technology List (ETL), which is part of the Government sponsored Enhanced Capital Allowance (ECA) scheme. The ECA scheme provides incentives to businesses who invest in eligible energy-saving equipment. With no mains supply gas, a conventional gas boiler was not an option.

Following a detailed site survey and the completion of the heat load calculations, we recommended the installation of two Daikin ASHP Low Temperature Altherma systems. These would provide low temperature hot water (LTHW) for the underfloor heating system on the ground floor and the first floor.  We also recommended a Thermodynamic Box which would feed a Heatrae-Sadia Unvented DD145HE Hot Water Cyclinder, providing the building with hot water as and when required.

Daikin air source heat pumps are designed to extract latent heat from the outside air and pump it inside to heat indoor spaces, rather than having to generate it from traditional fuel sources. Making use of outside air as a renewable energy resource not only reduces costs, but also leads to a dramatic fall in CO2 emissions.

Unvented water heating is currently one of the fastest growing sectors in the UK market, and the Heatrae-Sadia unvented cylinders provide outstanding levels of hot water performance, as well as comfort and, most importantly, energy saving.



Working closely with the on-site Project Manager and coordinating with the construction company, our team of engineers completed the installation in three phases. Phase One saw the installation of 240m of 16×1.5 Rehau Underfloor Heating Pipework, 160m2 of which ran on the ground floor, and 135m2 on the first floor. We were also able to secure two Daikin ERLQ016CW1 three-phase condensing units to the external wall.

During the course of Phase Two, we installed all of the refrigerant pipework and two Daikin EHBH16C9W Hydro boxes. Each box supplies its own floor, giving the consumer total control for each particular zone. We were also able to run the first fix of the electrical requirements.

Finally, in Phase Three, the refrigerant pipework was completed, as well as installation of the control and final electrical requirements. At this stage, we also fitted the Thermodynamic system, which would supply the hot water. This system is able to run independently of the Alterma system, enabling the complete shutdown of the heating system during the warmer months, and so further reducing energy consumption.


Khotah Stone now has complete control over its working and showroom environment. Not only can the Rehau Star 50 and Star 20 controls be used to adjust the temperatures of the rooms, but they can also set the system to warm up the building before the staff arrive in the morning, ensuring a comfortable working environment and complete peace of mind.

Thanks to the thermodynamic hot water system, there is a constant supply of hot water (550C) from the 150-litre hot water cylinder.

Finally, the installation was granted MCS Certification, as it met fully with the scheme’s requirements.

Call 01772 654402 to find out how Horsfield can help your business.