This case study shows an Air Source Heat Pump that we installed into a Grade II Listed Building.

When our client Alex began renovating his Grade II listed timber-framed home in Buckinghamshire, he set his sights on going completely gas-free.

Despite initial scepticism from heating engineers, Alex’s determination to install a heat pump paid off.

We fitted a Viessmann Vitocal 150-A heat pump, which now ranks highly on the Open Energy Monitor with a remarkable Seasonal Coefficient of Performance (COP) of 4.8.

This case study demonstrates the feasibility and benefits of using a heat pump in a heritage home, as well as the innovative techniques that made it successful.

Embracing Sustainability with Heat Pump Technology

Given the UK government’s goal to phase out gas boilers, air-source heat pumps are the ideal long-term solution.

The Viessmann Vitocal 150-A was a strategic choice of heat pump, as it offers excellent weather compensation controls. This makes it highly efficient in the cold weather.

Overcoming Challenges with a Heritage Home

Installing a heat pump in a 17th-century listed home required creative solutions. Initially, several contractors discouraged our client, Alex from pursuing the project. That was until he found a like-minded collaborator in Liam Barry, Projects Director at Custom Renewables Ltd.

Following a thorough heat loss survey, Liam determined that the house’s heat loss could be met with a 16 kW heat pump, especially with the installation of underfloor heating (UFH) on the ground floor and a re-pipe to the house to increase efficiency.

Choosing a Viessmann Heat Pump for Reliability and Efficiency

Custom Renewables decided to install the 16 kW Viessmann Vitocal 150-A because the Viessmann unit’s advanced weather compensation system helps maintain efficient heating even during temperature drops, while its compact internal buffer minimises defrosting requirements.

Paired with 18 solar PV panels and a 10kWh battery storage system, the heat pump covers most of the home’s energy needs, including an electric vehicle and hob, reducing reliance on grid electricity.

Managing Heritage Restrictions with Innovative Design

The listed status of Alex’s home introduced additional regulatory challenges. For instance, only specific external walls could be modified for piping, and only traditionally styled column radiators were approved. The home’s narrow, elongated layout also presented design challenges. To minimise visual disruption, piping was routed through concealed spaces on each floor. This centralisation minimised heat loss and preserved the historical aesthetic.

The couple opted for a novel high-efficiency “super cylinder” to manage hot water, a common challenge with heat pumps. Developed in collaboration with Heat Geek and Newark Cylinders, this advanced cylinder boasts up to 500% efficiency, enabling the heat pump to deliver consistently hot water without compromising overall system efficiency.

Cost-Saving Benefits and Comfort Gains

The installation costs were partially offset by a £7,500 Boiler Upgrade Scheme grant, making the transition more affordable. While additional expenses arose due to heritage requirements, the efficiency gains are already noticeable. Alex reports a significant drop in utility bills and minimal reliance on grid power. The new system provides a stable, draft-free warmth throughout the home, enhancing comfort while preserving the building’s historical charm.

A Blueprint for Sustainable Heating in Heritage Homes

This successful heat pump installation offers a compelling model for others looking to adopt sustainable heating in older properties. Our innovative approach to navigating regulatory challenges and optimising efficiency has made this Grade II listed home a leader in sustainable heating performance.

If you would like some help with your own installation, contact us today for some technical advice.

* All energy and performance claims are based on our own energy assessments and live monitoring of energy consumption.