Gas Boiler vs Heat Pump 2025: Complete Comparison Guide

Introduction: The Great Heating Debate in Belgium

In 2025, choosing a heating system represents one of the most important decisions for any Belgian homeowner. Between the condensing gas boiler, a proven and reliable technology, and the heat pump, a future-oriented solution favored by European energy policies, the dilemma is real.

At VCN Energy, with over 15 years of experience in installing and maintaining all types of heating systems in Belgium, we guide clients daily through this crucial choice. This article provides an objective and complete comparison to help you make the best decision based on your situation.

Understanding the Technologies: Operation and Principles

How does a condensing gas boiler work?

The condensing gas boiler represents the most advanced evolution of traditional boilers. Its principle is based on recovering the latent heat contained in the combustion gases.

• Natural gas combustion: The burner heats the water in the heating circuit
• Flue gas recovery: Unlike old boilers, the flue gases are not directly evacuated
• Water vapor condensation: The flue gases are cooled to condense the water vapor they contain
• Additional energy gain: This condensation releases additional energy that heats the return water

The efficiency of a condensing gas boiler can reach 109% on lower calorific value, compared to only 70-80% for an old generation boiler.

How does a heat pump work?

The heat pump works on the reverse principle of a refrigerator. It captures calories present in the environment (air, water or ground) to transfer them inside your home.

• Capturing calories: The evaporator absorbs heat from the source (outdoor air for an air-to-water HP)
• Compression of refrigerant: The compressor increases the pressure and therefore the temperature of the refrigerant
• Heat release: The condenser transfers this heat to the heating circuit
• Refrigerant expansion: The expansion valve returns the refrigerant to low pressure to restart the cycle

The COP (Coefficient of Performance) of a modern heat pump varies between 3 and 5, meaning that for 1 kWh of electricity consumed, it produces 3 to 5 kWh of heat.

Installation Cost Comparison

Price of a condensing gas boiler in Belgium

Installing a condensing gas boiler in 2025 represents an investment generally between:

• Entry level (Vaillant ecoTEC, Bulex Thema Condens): €2,500 to €4,000 excl. VAT
• Mid-range (Viessmann Vitodens, Remeha Tzerra): €4,000 to €6,000 excl. VAT
• High-end (Viessmann Vitodens 300, Vaillant ecoTEC exclusive): €6,000 to €9,000 excl. VAT

Price of an air-to-water heat pump in Belgium

The investment for an air-to-water heat pump is significantly higher:

• Entry level (LG Therma V, Panasonic Aquarea): €8,000 to €12,000 excl. VAT
• Mid-range (Daikin Altherma, Mitsubishi Ecodan): €12,000 to €18,000 excl. VAT
• High-end (Vaillant aroTHERM plus, Viessmann Vitocal): €18,000 to €25,000 excl. VAT

Operating Cost Comparison

For a 150 m² house with average insulation in Belgium (heating requirement of approximately 15,000 kWh/year):

Condensing gas boiler:

• Gas consumption: approximately 16,500 kWh (91% efficiency)
• Gas price in 2025: approximately €0.08/kWh
• Annual cost: €1,320

Air-to-water heat pump:

• Electricity consumption: approximately 4,300 kWh (average COP of 3.5)
• Electricity price in 2025: approximately €0.28/kWh
• Annual cost: €1,204

Subsidies in Belgium 2025

Heat pump subsidies in Wallonia

Wallonia offers attractive subsidies for heat pumps:

• Air-to-water HP: up to €4,000 base subsidy
• Geothermal HP: up to €6,000 base subsidy
• Low income bonus: possible 50% increase

Heat pump subsidies in Brussels

Brussels Environment also offers incentives through RENOLUTION subsidies:

• Air-to-water HP: between €3,500 and €4,500 depending on income
• Geothermal HP: between €4,500 and €6,500 depending on income

Gas boiler subsidies in 2025

Important change: Since 2024, subsidies for gas boilers have been abolished in most Belgian regions.

Maintenance Comparison

Gas boiler maintenance

Annual gas boiler maintenance is mandatory in Belgium:

• Frequency: every year in Wallonia and Brussels, every 2 years in Flanders
• Average cost: €120 to €180 per maintenance
• Certificate: issued by a certified technician

Heat pump maintenance

Heat pump maintenance is less demanding but remains recommended:

• Frequency: recommended annually
• Average cost: €150 to €250 per maintenance

Conclusion: Our VCN Energy Recommendation

There is no universal solution. The choice between gas boiler and heat pump depends on your specific situation:

• Your available budget
• The insulation condition of your home
• Your long-term vision
• Your environmental awareness

At VCN Energy, we carry out a free personalized study to evaluate your situation and recommend the most suitable solution.

Contact us at 0470 27 16 08 or book your consultation online for expert advice.