From Failing Boiler to a Future-Proof Heat Pump System
160m² Detached Bungalow | Epsom, Surrey
The Challenge
Our client had one clear goal: replace their ageing gas boiler with an air source heat pump to reduce running costs and future-proof their home.
However, during our initial survey it became obvious that installing a heat pump immediately would have been the wrong decision.
BEFORE: Gas Boiler
AFTER: Vaillant Heat Pump
Following a room-by-room heat loss calculation, we established that the property required only 7kW of heating at the design temperature. This confirmed that a Vaillant aroTHERM Plus 7kW would be perfectly sized for the home in Epsom, Surrey.
The system was then designed to operate at a 45°C flow temperature, maximising efficiency and seasonal performance.
Before any heat pump could be installed, the existing heating system needed attention.
Stage 1 – Making Sure the Existing System Was Ready
The existing installation consisted of a 35kW Ideal combi boiler. Unfortunately, the boiler had developed a leak and the customer was also concerned that the underfloor heating wasn’t performing correctly.
Rather than replacing equipment and hoping for the best, we spent an entire day:
- Diagnosing and repairing the boiler leak
- Investigating the underfloor heating performance
- Checking the existing pipework and controls
- Assessing whether the system could successfully operate at low temperatures
During this investigation we uncovered several additional issues that would have negatively affected the future heat pump installation. By identifying these problems early, we avoided installing an expensive renewable heating system onto a network that wasn’t ready for it.
Only once we were completely satisfied with the performance of the underfloor heating did we move to Stage 2.
Stage 2 – Air Source Heat Pump Installation
With confidence that the heating distribution system would perform correctly, we removed the existing gas boiler and installed:
- ✔ Vaillant aroTHERM Plus 7kW – Perfectly matched to the calculated heat loss of the property.
- ✔ 210L Slimline Unvented Cylinder – Sized for four occupants, providing excellent hot water performance in the available space.
Internal installation of the 210L Vaillant slimline cylinder.
This allows the heat pump to automatically adjust flow temperatures depending on outdoor conditions, improving efficiency throughout the heating season.
Heating System Improvements
To ensure every room achieved the required comfort temperatures at low flow temperatures, we upgraded radiators and valves to match the new low-temperature design.
Final thermal imaging results confirming even heat distribution.
The thermal imaging carried out after commissioning clearly demonstrated an even heat distribution across the underfloor heating circuits, confirming the system was operating as designed.
Performance Summary
Property: 160m² Detached Bungalow | Epsom, Surrey
Design Heat Loss: 7kW
Heat Pump: Vaillant aroTHERM Plus 7kW
Flow Temperature: 45°C
System Type: Open Loop
Controls: Weather Compensated
Predicted SCOP: 3.91
The Result
The customer now benefits from lower running costs, stable indoor comfort, and a correctly sized renewable heating system. This installation is fully compatible with low-cost electricity tariffs and future battery storage.
Ready to Future-Proof Your Home?
At Evo Heating & Renewables, we specialise in precision-designed heating systems that deliver efficiency and comfort for years to come. Whether you’re in Epsom, Surrey, or the surrounding areas, we’re here to help.
Thinking about the same change?
Every system we design starts with a room-by-room heat loss survey rather than a like-for-like swap. Read more about heat pump installation in Epsom, see how we approach bespoke low temperature heating design, or find out what it means to work with a Heat Geek Assured installer in Surrey.
More from our work: from an oversized quote to a precision-engineered heat pump system, and replacing a 30-year-old oil heating system. Browse all of our case studies, read our customer reviews, or get in touch to book a survey.
