By Reliant Energy Solutions, ECO4 Grants and Energy Efficiency Experts

In the UK, homes are rapidly moving away from conventional fossil fuel heating and towards low-carbon, renewable alternatives. Old, inefficient boilers are being replaced with greener technologies like air source and ground source heat pumps as the government approaches its Net Zero 2050 goal.

The UK government actually plans to install at least 600,000 heat pumps annually over the next five years through programs like the Boiler Upgrade Scheme (BUS). However, less than 2% of UK households currently utilize a heat pump, while over 80% still rely on boilers.

Which is better, a heat pump installation in the UK or sticking with your old boiler? To help you choose the best option for your property, Reliant Energy Solutions breaks down the differences in this guide, addressing cost, efficiency, grants, and home comfort.

How Do Boilers and Heat Pumps Work?

Gas Boilers

About 80% of homes in the UK still use gas boilers. These systems heat water by burning oil, LPG or natural gas, and then circulate the heated water through taps and radiators. Even with their 94% efficiency, contemporary condensing boilers still use fossil fuels.

Heat Pumps

Heat pumps function differently than refrigerators because they use refrigerant technology to capture heat energy from the ground or air rather than burning fuel. This focused heat is utilised to warm the hot water cylinder, underfloor heating, and radiators in your house.

Though less than 2% of homes in the UK have one installed, heat pumps are not new—more than 16% of homes in Europe currently use them.

Are Heat Pumps More Expensive Than Boilers?

In the UK, cost is one of the most often asked issues by homeowners.

• Gas Boiler Costs: The average cost of a new boiler, including installation, is between £2,500 and £4,500.
• Air Source Heat Pump Costs: The cost of installing an air source heat pump was approximately £12,600 on average in 2024; however, the government’s Boiler Upgrade Scheme (BUS) provides a £7,500 incentive, bringing the average cost down to £5,100. 
• Ground Source Heat Pumps: Ground source heat pumps are more costly, usually costing between £18,000 and £25,000. 

If you qualify for the ECO4 Boiler Replacement Scheme, you may be able to replace an inefficient non-condensing boiler for free.

Do Heat Pumps Require Other Home Improvements?

In certain cases, yes. Heat pumps function best in homes with adequate insulation since they run at lower flow temperatures than boilers.

• You could have to install underfloor heating or upgrade to larger radiators.
• Upgrade the insulation in your loft, cavity wall, or floor.
• If a combi boiler is being replaced, add a hot water cylinder.

Reliant Energy Solutions can carry out a free home energy assessment to check if you’re eligible for grants under ECO4 or GBIS.

Which Is More Efficient: Heat Pumps or Boilers?

• Modern Condensing Boilers: 92–94% efficient 
• Heat Pumps: 250–450% efficient (for every 1kWh of electricity, they provide 2.5–4.5 kWh of heat) 

This makes heat pumps three to four times more efficient than even the best gas boilers.

Are Heat Pumps Better for the Environment?

Of course. Currently, more than 50% of electricity in the UK is carbon neutral, and that percentage is growing. Household carbon emissions are greatly reduced when gas is replaced with electricity.

In contrast, CO₂ is immediately added to the atmosphere when gas, oil, or LPG are burned. At least half of all households must have a heat pump installed if the UK is to achieve Net Zero by 2050.

Will a Heat Pump Cost More to Run?

This depends on your tariff and installation quality.

• Electricity costs are still higher per kWh than gas. 
• But specialist tariffs (e.g., from Octopus Energy or OVO) cut running costs for heat pump owners. 
• With the right setup, heat pumps can actually be cheaper to run than boilers, especially in insulated homes. 

Example:

• Gas boiler annual heating cost: ~£823 
• High-efficiency heat pump on a specialist tariff: ~£379 

Will a Heat Pump Be Noisier or Leave Me Colder?

• Noise: A modern air source heat pump is about as loud as a dishwasher (40–60 decibels). Proper installation ensures it won’t disturb you or neighbours. 
• Warmth: If designed and installed correctly, a heat pump will keep your home just as warm as a boiler, even in cold UK winters. 

Reliant Energy Solutions only works with MCS-certified installers, ensuring your system runs at peak performance.

Alternatives If You Don’t Want a Heat Pump

If a heat pump isn’t right for your property, you still have options:

• Free Boiler Grants (ECO4): Replace your old non-condensing boiler with an efficient condensing boiler. 
• Biomass Boilers: Renewable but less common in urban areas. 
• Infrared & Electric Heating Panels: Suitable for small or highly insulated homes. 
• Solar PV & Solar Thermal: Can be paired with a boiler or heat pump for hybrid solutions. 

Grants & Funding Available in 2025

Here are the main government-backed schemes:

• ECO4 Boiler & Insulation Grants: Free upgrades for low-income or vulnerable households. 
• Great British Insulation Scheme (GBIS): Free insulation improvements. 
• Boiler Upgrade Scheme (BUS): £7,500 grant for heat pumps. 
• 0% VAT on Renewables: No VAT on solar panels, heat pumps, and insulation until 2027. 

Reliant Energy Solutions can check your eligibility for free and help with the full application process.

Final Word from Reliant Energy Solutions

At Reliant Energy Solutions, we specialise in helping UK households access government grants for free boilers, insulation, and renewable energy systems. Whether you’re considering upgrading to a heat pump or replacing your old boiler, our team can guide you through every step—from eligibility checks to installation.

Ready to cut bills and future-proof your home? Contact Reliant Energy Solutions today for a free assessment.