Warmtepomp: Praktische stappen om verstandig te kiezen

Google Trends registered search interest for warmtepomp in Belgium at its peak — that spike usually means people are at a decision point: thinking about replacing gas, applying for subsidies, or quoting installers. If you’re reading this, you probably want to know whether a warmtepomp fits your house, how to avoid bad installers, and where the real savings are. I’m going to skip the fluff and give you the steps I wish every homeowner followed before signing a contract.

How do I know a warmtepomp is right for my house?

Short answer: usually yes, but not always. A warmtepomp works best when the house is reasonably insulated and uses low-temperature distribution (underfloor heating or oversized radiators). Start with a real heat-loss calculation — not a quick guess by an installer. I see homeowners skip this and pay for an oversized system or get disappointing performance.

• Step 1: Order a certified heat-loss (U-value) survey. It tells you the kilowatt demand on the coldest day.
• Step 2: Check insulation — walls, roof, windows. Small improvements often beat a larger heat pump.
• Step 3: Look at your radiators. If your radiators are tiny, you’ll need bigger ones or underfloor heating for efficiency.

And yes — the word warmtepomp matters here. Air-to-water, ground-source, and air-to-air systems behave differently. The choice depends on your plot, noise tolerance and budget.

Which warmtepomp types exist and when to pick each?

People ask me: what’s the easiest option? Here’s the pragmatic breakdown.

• Air-source heat pump (air-to-water): Lowest install cost, common in Belgium. Works well if you have decent insulation. Performance falls off in deep cold.
• Ground-source (geothermal): Highest efficiency and stable output, but expensive and needs garden space or drilling permits.
• Air-to-air heat pump: Good for replacing electric heating or for apartments. Cheaper but offers no hot water unless combined with another unit.

What actually works is sizing the unit to the calculated heat demand and choosing a unit with a good seasonal performance factor (SCOP). Don’t be seduced by headline COPs measured at ideal lab temperatures.

How much does a warmtepomp cost and what’s the true ROI?

Costs vary. In Belgium expect a basic air-source system (including installation) from several thousand euros up to around 15,000–20,000 EUR for full replacement and upgraded radiators or buffer tanks. Ground-source can double that. But raw price is only part of the story.

Calculate ROI using:

1. Estimated annual kWh demand (from your heat-loss calc).
2. Current price of electricity vs gas.
3. Seasonal performance factor (SCOP) rather than instant COP.
4. Available subsidies and tax incentives in your region.

Tip: I always run a simple spreadsheet: baseline energy cost today vs expected energy cost with the warmtepomp, subtract maintenance and amortization. If subsidies drop payback from 12 years to 6–8 years, it’s a different decision.

Are there Belgian subsidies or regulations I must know?

Yes — subsidies differ by region (Flanders, Wallonia, Brussels) and they change. Always check your regional portal before budgeting. For a starting point, the Flemish energy site has clear subsidy pages and practical guides, and the European Commission publishes guidance on efficient heating systems.

Useful links: Energiesparen (Flanders), Heat pump (Wikipedia), and EU energy efficiency guidance. Put those URLs in your folder for subsidy applications and technical specs.

What are the most common installation mistakes and how to avoid them?

I’ve seen the same mistakes repeatedly. Avoid these, and you’ll save money and headaches.

• Wrong sizing: An oversized warmtepomp short-cycles, wasting energy and wearing out components. Get a proper heat-loss calculation and insist on matching supply curves.
• Poor hydraulic setup: Missing buffer tanks, wrong pump control or lack of weather compensation leads to unstable temperatures. Ask your installer to explain flow rates and buffer sizing in plain language.
• Ignoring domestic hot water (DHW): Some air-source units struggle to reliably provide high-temperature DHW without a booster. If you need 60°C backup, plan for it.
• Installer incentives: Low quotes can hide poor design or cheap components. Check references and warranties.

Here’s the catch: a good installer sells performance, not just a box. Ask to see previous installations, demand a written commissioning report, and require a controller that logs temperatures and runtimes.

Step-by-step checklist before you sign any contract

1. Get three quotes based on the same heat-loss spec.
2. Ask for SCOP, noise level (dB(A)) at 1 meter and at property boundary, and full thermal curves.
3. Request a written list of additional works (radiators, controls, permits).
4. Confirm warranty details: compressor, exchanger, workmanship.
5. Check installer certification and insurance; ask about commissioning and handover documents.

Commissioning and first season: what to watch

Commissioning matters more than most homeowners realize. A properly commissioned system will modulate according to outside temperature and avoid short cycling.

• During handover, insist on a log showing setpoints, flow temperatures and run hours.
• Check that the pump runs at low speed most of the time — that’s a sign of good modulation.
• Monitor electricity use the first winter. If consumption is much higher than your estimates, contact the installer immediately.

Maintenance: how often and what costs?

Maintenance is simpler than for combustion boilers but still needed. Annual checks typically cost a few hundred euros and include refrigerant circuit inspection, fan and coil cleaning, and control updates. Factor this into lifetime costs.

Noise, aesthetics and permits — practical tips

Outdoor units make noise. You can reduce impact by placing them on anti-vibration mounts, behind a screen, or on the side of a building away from neighbours. Check local noise ordinances and get neighbour buy-in early. For ground-source, check for drilling permits and proximity rules.

What about hybrid systems or keeping the boiler?

Hybrid setups keep the gas or oil boiler as backup and lower peak electricity use. They can be a sensible transition option if you’re uncertain or if your insulation isn’t complete. But hybrids complicate controls—get a system that manages switching automatically based on temperature and price signals.

Reader Q&A: Common worries I hear

Q: Will a warmtepomp work in an older Belgian house with radiators? A: Often yes, but you may need larger radiators or higher-flow systems. Low-temperature distribution improves performance.

Q: Are heat pumps reliable long-term? A: Yes — compressors and inverters have improved. Choose a reputable brand and ensure good commissioning. Expect 15–20 years with proper maintenance.

Final recommendations — what I would do if it were my house

I would start with a heat-loss calculation, then insulate weak spots. Next, get quotes for an air-source heat pump sized to the real heat need and compare the net cost after subsidies. If I had garden space and planned to stay 15+ years, I’d get a geothermal quote. And crucially: I’d pick an installer who explains the hydraulic schematic and provides commissioning logs — that separation between a working system and a box on the lawn is everything.

If you want, save this article and use the checklist when you ask for quotes. It avoids the most expensive mistakes I’ve seen homeowners make — and makes the warmtepomp actually pay off.