"Do Heat Pumps Work in Cold Weather? A Real-World Example from a Southwater Home"

Short answer: yes but only when the house is properly prepared.

There has been growing discussion about how air source heat pumps perform in cold weather, especially in older homes. With the recent cold spell, I wanted to share a real example from my own home in Southwater. I’ll explain what has worked well, what challenges we faced, and why preparation made such a difference.

The Property: A Complex Setup

Our home is not a modern or straightforward build. It is an end-terrace property, around 200 years old, with a combination of construction types. These include solid wall sections, rat-trap bond brickwork, and more recent cavity wall additions.

The house is two storeys high with roughly three to four bedrooms. It also includes:

• An older extension that dates back about 150 years

• A newer extension, completed approximately a year ago, measuring around 27 square metres

This is a mixed and challenging property, rather than a typical modern home.

Insulation Came First, and It Made a Difference

Before installing the air source heat pump, we prioritised improving the building’s insulation. This was not an afterthought but a deliberate first step.

The work we carried out included:

• Increasing loft insulation to 270 millimetres by adding 170 millimetres to the existing layer

• Adding cavity wall insulation, including retrofit injection where it was possible

• Installing floor insulation in the new extension

These upgrades were completed a few weeks before the heat pump was installed. The timing was intentional. Our aim was to reduce heat loss first, rather than relying on the heating system to compensate for inefficiencies.

Radiators Instead of Underfloor Heating

We do not have underfloor heating. Instead, prior to the installation, we upgraded all but one of the radiators in the house to large triple-fin models.

This matters because heat pumps operate best at lower flow temperatures, which means the heat emitters need to be sized correctly. In many older homes, standard radiators are simply not large enough to deliver heat effectively at these temperatures.

Upgrading the radiators made a noticeable difference to how evenly heat is distributed throughout the home.

The Heat Pump System

We installed a Samsung air source heat pump with a twin-fan design. I won’t go into technical specifications here, as the key point is not the model itself, but the fact that the system was installed into a property that had already been properly prepared.

Performance During Cold Weather

During the recent period of cold weather, the house has remained consistently warm. It’s true that the indoor temperature rarely goes beyond 20 to 21 degrees Celsius during the coldest times. This isn’t because the system is struggling, but because it is designed to provide steady background heat rather than rapid temperature boosts.

What we have experienced instead includes:

• Consistent and even warmth throughout the home

• No sudden temperature fluctuations

• A level of comfort that is noticeably better than before the insulation improvements

We use a basic thermostat, set to maintain around 20 to 21 degrees Celsius during the day, and about 19 degrees in the evening. The system provides a constant, even level of heat rather than cycling aggressively on and off.

This feels very different from how the house was heated previously.

The Previous Setup: Expensive and Uneven Heating

Before the heat pump, we relied on an electric boiler, which was extremely expensive to run. Because of this, we depended heavily on a log burner to keep warm.

While the log burner worked well for heating the lounge, it was not capable of heating the rest of the house effectively, particularly during colder periods. This resulted in uneven temperatures and several rooms being left uncomfortably cold.

By comparison, the heat pump now provides a stable and comfortable temperature throughout the entire home, without the need for supplementary or spot heating.

Main Takeaway: Preparation Is Key

Based on our experience, the conclusion is straightforward:

Older homes can work well with heat pumps, but only if they are properly prepared first.

Cold weather itself is rarely the main issue. The most common problems tend to be inadequate insulation, undersized radiators, or expecting a heat pump to behave like a traditional high-temperature boiler.

When the building fabric is improved first and the heating system is correctly sized, a heat pump can perform exactly as intended — even in older and more complex properties.

Final Thoughts

Heat pumps are not a shortcut or a one-size-fits-all solution. What they do is reveal how efficiently a building performs. In that sense, they reward good preparation and make weaknesses more visible — issues that were often masked by older, high-temperature heating systems.

If you are considering a heat pump, or are unsure why your current system is not delivering the results you expected, understanding the building itself is the most important first step. Everything else follows from that.