# Heat Pump Guide: Types, Sizing and Maintenance > Complete guide to heat pumps: air source vs ground source, how they work, maintenance schedule, common myths debunked, and sizing tips. Canonical: https://renoquant.com/heat-pump-guide Prices updated: 2026-03 ## Understanding Heat Pumps Heat pumps are the most energy-efficient heating technology available for homes. They extract renewable heat from the environment and deliver it to your home at 2.5-4 times the efficiency of any combustion-based heating system. This guide covers everything you need to know before investing in a heat pump. ### Air Source vs Ground Source | Feature | Air Source (ASHP) | Ground Source (GSHP) | |---------|------------------|---------------------| | Heat source | Outdoor air | Underground (via boreholes or trenches) | | Efficiency (SCOP) | 2.5-3.5 | 3.5-4.5 | | Installation cost | EUR 7,000-16,000 | EUR 15,000-30,000 | | Installation time | 3-5 days | 1-3 weeks | | Garden space needed | Minimal (outdoor unit) | Large (trench) or minimal (borehole) | | Noise | 40-55 dB outdoor | Near-silent | | Lifespan | 15-20 years | 20-25 years (ground loop: 50+ years) | | Performance in extreme cold | Drops to COP 2.0 at -10C | Stable year-round | | Best for | Most homes, retrofits | Rural homes with land, new builds | For the vast majority of homeowners, an air source heat pump is the right choice. The lower cost, simpler installation, and minimal garden disruption make it practical for both new builds and retrofits. Ground source is worth considering only if you have significant outdoor space and want maximum long-term efficiency. ### How Heat Pumps Work Every heat pump contains the same four core components: 1. **Evaporator** - Absorbs heat from the air or ground into a refrigerant fluid, which evaporates at very low temperatures (as low as -25C) 2. **Compressor** - Compresses the refrigerant gas, raising its temperature from 5-10C to 55-75C (this is where the electricity is consumed) 3. **Condenser** - Transfers the heat from the hot refrigerant to your heating water circuit 4. **Expansion valve** - Reduces the refrigerant pressure, cooling it back down to restart the cycle The key insight is that the compressor does not create heat. It concentrates heat that already exists in the environment. Even at 0C, outdoor air contains significant thermal energy. The compressor simply moves this energy from a cold source (outside) to a warm destination (your home). ### Maintenance Schedule | Interval | Task | DIY or Professional | Estimated Cost | |----------|------|-------------------|---------------| | Monthly | Check system pressure gauge | DIY | Free | | Quarterly | Clean or replace air filters | DIY | EUR 5-15 per filter | | Annually | Full professional service | Professional | EUR 100-200 | | Every 2-3 years | Refrigerant level check | F-Gas certified engineer | Included in service | | Every 5 years | Full system performance audit | Professional | EUR 150-300 | | Year 10-15 | Compressor or fan motor check | Professional | EUR 200-800 if repair needed | Keep the area around the outdoor unit clear of leaves, snow, and debris. Ensure at least 300mm clearance on all sides for airflow. In winter, check that the defrost cycle is working correctly (brief periods of steam from the outdoor unit are normal). ### Common Myths Debunked **Myth: Heat pumps do not work below freezing.** Reality: Modern ASHPs operate efficiently down to -15C to -20C. In Norway, where winter temperatures regularly reach -20C, heat pumps are the most popular heating system, installed in over 60% of homes. **Myth: Heat pumps are too noisy for residential areas.** Reality: At 40-55 dB, a modern ASHP is quieter than a normal conversation (60 dB). Noise regulations require installation at least 1 metre from boundaries and below 42 dB at the nearest neighbour's window. **Myth: You need underfloor heating for a heat pump.** Reality: Heat pumps work with radiators, but you may need to upsize some radiators by 1-2 sizes because heat pumps produce water at 35-55C compared to a boiler's 60-80C. Many homes only need 2-3 radiators replaced, not the entire system. **Myth: Heat pumps are too expensive without grants.** Reality: Even without grants, a heat pump saving EUR 300-500/year vs oil heating pays back in 12-18 years, with 5-10 years of additional free heating. With grants, payback drops to 5-10 years. Use our [heat pump calculator](/heat-pump-calculator) to see your specific payback period. **Myth: Heat pumps use too much electricity.** Reality: A well-sized heat pump for a 100 sqm home uses 5,000-7,500 kWh of electricity per year, producing 14,000-21,000 kWh of heat. This adds EUR 1,000-1,800 to your electricity bill but eliminates your entire gas or oil bill. Pairing with [solar panels](/solar-panel-calculator) can offset 30-50% of this electricity consumption. ## Frequently Asked Questions ### What is the difference between air source and ground source heat pumps? Air source heat pumps extract heat from outdoor air and cost EUR 7,000-16,000 installed. Ground source heat pumps extract heat from the ground via boreholes or trenches and cost EUR 15,000-30,000. Ground source is more efficient (SCOP 3.5-4.5 vs 2.5-3.5) but the extra cost rarely pays back in running cost savings. ### How does a heat pump work in simple terms? A heat pump works like a fridge in reverse. It absorbs heat from outside air or ground (even in cold weather), compresses it to raise the temperature, then releases it into your heating system. The compressor uses electricity, but the heat energy output is 2.5-4 times greater than the electrical input. ### How often does a heat pump need servicing? Annual servicing is recommended, costing EUR 100-200. The service includes checking refrigerant levels, cleaning filters, inspecting electrical connections, and verifying system performance. Unlike gas boilers, there is no legal requirement for annual safety checks, but regular servicing maintains efficiency and warranty. ### Do heat pumps need planning permission? In most European countries, air source heat pumps fall under permitted development and do not need planning permission, provided they meet noise limits and are at least 1 metre from any boundary. Ground source boreholes may need planning permission. Conservation areas and listed buildings have stricter rules. ### What is the SCOP rating and why does it matter? SCOP (Seasonal Coefficient of Performance) measures average efficiency over a full heating season. An SCOP of 3.0 means the heat pump produces 3 kWh of heat for every 1 kWh of electricity. Higher SCOP means lower running costs. Look for SCOP 2.8+ for air source and 3.5+ for ground source. --- Interactive version with calculator: https://renoquant.com/heat-pump-guide. Figures are estimates; final quotes vary by site conditions, materials, and region.