Retrofit Air Source Heat Pump Solution for Period Property Ticks all the Renewable Energy Boxes

When James Miskin decided to replace his ageing boiler he was faced with the alternative of a new modern gas boiler or a move to renewables to deliver all his property’s heating and hot water requirements. “ Looking for a renewable based solution for heating and hot water was clearly the right thing to do and I was keen to make the transition from gas to renewables,” he says.

After research and talks with renewable energy consultancy Your Future Energy, the best solution, taking into consideration the style of property and required operational performance, was the installation of Daikin hydro split  Air to Water High Temperature Heat Pumps. The project was completed with Air Craft taking full responsibility for the installation and thereby demonstrating that heat pump technology can be effectively applied within older properties and can integrate seamlessly with existing or new radiators and pipework without having to replace an entire system.

The large 1840s period home in Oxford, with a 1970s rear extension, has a large garden including a garage outbuilding. Considerable investment had already been made into energy saving initiatives at the property where possible with loft and cavity insulation, although the original building was a solid wall construction. The initial idea was to install a Ground Source Heat Pump for heating and hot water but this approach was rejected due to the 94 m depth of the proposed four bore holes and the risk of collapsing earthwork due to being close to an old quarry.

The renewable energy consultancy has vast experience in finding the right low carbon solution for homes and businesses, designing practical systems for different types of properties that completely fulfil the needs of the occupants. The company had worked closely with Air Craft, a Daikin Sustainable Home Expert and a Microgeneration Certification Scheme (MCS) certified company, on a number of projects and recognised the quality of their installation work including the challenges of retrofitting heat pump systems into period less energy efficient homes.

Having undertaken a detailed appraisal of the property, including room by room heat loss calculations, a proposal  for the Daikin system was made which included the specification of two Altherma Heat Pumps to cover the calculated demand for the property and counteract the relatively high heat loss of a solid wall building.

These outdoor units would be installed out of sight outside the garage and connect with two units inside.  A new three phase power supply was needed due to the potential maximal load at the property.  A trench around 25 metres long between the garage and the house would be dug for a highly insulated 150 mm MCS approved pipework to carry to the house four pipes for the heating flow and return, hot water and hot water return loop. The cold water main was also diverted to the garage and brought back to the house in the same trench to effectively balance hot and cold water pressures. A return power feed and the communications cables were also run in the trench. This culminated at a manhole adjacent to the outside solid wall and from there pipes and cables were fed through the wall, up into the house.

Located in a conservation area, full planning permission for the installation had to be obtained because of the need for two units – one is considered permitted development. Key concerns related to the potential sound and sight disruption caused by the outdoor units to neighbouring properties, including social housing. After careful preparation of all the necessary documentation including operational certifications for the heat pumps as well as comprehensive system layout and product elevation drawings, permission was granted. James project managed all the electrical work, including liaison with electricity supplier, electrical contractor and carefully organising the timing for the disruptive trenchwork. In hindsight, for him this was the most complex and challenging part of the project, not least working out what was actually the best strategy for the new electrical supply, together with the termination of the legacy gas and electrical supplies after completion.

Air Craft verified the system designed by the energy consultancy and the new ASHP system was up and running in  August 2021. Effective deployment of the installation team to meet deadlines, overcoming  the challenges presented by a solid wall building and positioning the new pipework in a manner which would not detract from the aesthetics of the property’s interior were key to the success of the project. New aluminium radiatiors, fully compatible with heat pump technology, were installed throughout the property by Air Craft who utilised the existing pipework.

Now, after several months of enjoying the cost effectiveness of Daikin heat pump technology, James feels fully vindicated by the decision to go down the renewables route. The Daikin Altherma ASHPs are renowned for their low operational sound levels (38 decibels) and are completely unnoticeable inside the home or by neighbours when in operation.

They are programmed to provide hot water constantly but with flow/return pump operating twice daily during peak usage hours to minimise delays at the tap. There is more than sufficient supply from the 300 litre direct hot water cylinder. The controls, simple to understand and operate, are linked to standard room thermostats in the house.

With the dramatic increase in the cost of gas, the switch to a renewable energy source could not have come at a better time. “The installation will of course pay for itself over an extended period of time and is eligible for government funding under the now closed RHI scheme. But for me it is more about energy conservation now and reducing our carbon footprint, and investing into the legacy of the property as the current owners. Both Air Craft and Your Future Energy have been instrumental in achieving these aims,” says James.