How to Use a Heat Pump: Installation, Efficiency, and Best Practices

The number of heat pump installations is set to skyrocket in the next decade or so, with around 25 million units expected to be installed in homes.

If you're considering making the switch, understanding how to use a heat pump correctly is crucial for maximizing efficiency and comfort.

This guide covers the essentials—from choosing the right outdoor unit placement to managing radiator temperatures and integrating underfloor heating. Here’s everything you need to know to get the most out of your heat pump system.

Choosing the Right Location for Your Heat Pump

Outdoor Unit Placement: What You Need to Know

Most homeowners opt for air-to-water heat pumps, which draw heat from the outside air and deliver it via water-based systems like radiators or underfloor heating. Unlike a compact gas boiler, a heat pump has a larger outdoor unit, typically around 1.2 meters high, 800 mm deep, and 1.2 meters wide. It resembles the external units seen with air conditioning systems.

Key Considerations for Outdoor Placement:

• Aesthetics and Space: The unit can be placed against the house or even at the end of the garden, as long as you use pre-insulated piping to minimize heat loss.

• Distance from the Home: While distance can cause minor energy loss, modern insulated pipes significantly reduce this, making it feasible to locate the unit away from the main building if desired.

• Noise and Airflow: Keep the unit away from bedrooms or living spaces where noise might be an issue, and ensure good airflow for optimal performance.

  
  

Understanding Radiator Temperatures and Flow Rates

Why Heat Pump Radiators Run Cooler

Heat pumps work differently from gas boilers. They don’t produce the same intense, high-temperature heat. Instead, they maintain a lower, more consistent flow temperature, typically around 55°C or even lower, depending on the system.

Traditional Gas Boiler vs. Heat Pump:

• Gas Boiler: Intermittent high-temperature bursts (up to 65-70°C), turning on and off as needed.

• Heat Pump: Steady, lower temperature, continuous flow, optimized for maximum efficiency.

  
  

Weather Compensation for Efficiency

Many modern heat pumps include weather compensation technology, which adjusts the water temperature based on the outdoor air temperature, improving efficiency and comfort. New refrigerants like R290 (propane) allow some models to achieve up to 65°C, making them capable of providing hotter water than many traditional gas boilers.

Continuous Operation vs. On-Off Cycling

Why Long, Gentle Operation is Best

Heat pumps, unlike conventional boilers or electric heaters, work best when running for extended periods at lower power. This approach:

• Reduces Wear: Compressors are often rated by the number of start-stop cycles, so minimizing these extends the unit’s life.

• Improves Efficiency: Continuously operating at lower temperatures increases the Coefficient of Performance (COP), reducing energy costs.

• Enhances Comfort: Steady heat is more comfortable and avoids the hot-cold cycling common with traditional systems.

Most residential systems are designed for no more than three starts per hour, keeping wear to a minimum and extending the lifespan of the compressor.

Should You Use Underfloor Heating with Heat Pumps?

Pros and Cons of Underfloor Heating

Underfloor heating is a natural partner for heat pumps, as both systems benefit from low, steady temperature operation. However, it does have some specific characteristics:

Pros:

• Comfortable, Even Heat: Provides consistent warmth, ideal for open-plan spaces.

• Space Saving: Frees up wall space by eliminating the need for bulky radiators.

Cons:

• Slow Response Times: Because it relies on the thermal mass of the floor, it can take longer to heat up and cool down.

• Higher Installation Costs: Retrofitting can be expensive, particularly if floors need to be lifted or resurfaced.

  
  

Despite these challenges, underfloor heating remains a popular choice for new builds and high-end renovations.

Exploring Air-to-Air Systems

When to Consider Air-to-Air Heat Pumps

While air-to-water systems dominate the UK market, air-to-air heat pumps are also an option. These systems heat and cool using air, making them ideal for homes that don’t already have a hydronic (water-based) heating system.

Key Benefits:

• Heating and Cooling: Reversible for year-round comfort.

• Faster Response: Heats spaces quickly, similar to traditional air conditioning.

• Space Efficiency: Eliminates the need for radiators, freeing up wall space.

However, they lack the central hot water capabilities of water-based systems, making them less suitable for homes reliant on hot water radiators.

Final Thoughts: Getting the Most from Your Heat Pump

Heat pumps represent a fundamental shift in how homes are heated and cooled, offering a cleaner, more energy-efficient alternative to traditional gas boilers. However, correct installation and proper use are essential for maximizing their benefits.

Whether you’re installing a system for the first time or upgrading an older model, keep these best practices in mind:

• Choose the right location for your outdoor unit.

• Understand radiator temperature settings.

• Consider underfloor heating for maximum comfort.

• Aim for long, steady operation to protect the compressor.

With thoughtful design and maintenance, a heat pump can provide reliable, eco-friendly heat for decades.