High-Temperature Air-Source Heat Pumps: Can You Really Keep Your Old Radiators?

If you’re thinking about replacing your old oil or gas boiler, you’ve probably heard the claim: “Air-source heat pumps only work with underfloor heating; if you have radiators, they won’t work for you”.

We have good news: that claim is outdated. Thanks to technological advances and the use of new refrigerants, it’s now entirely possible to switch to cleaner energy without tearing up the floors throughout your home or replacing your aluminum or cast-iron radiators. The key is a high-temperature air-source heat pump.

The temperature problem: Why wasn’t it possible before?

To understand why older radiators were the “enemy” of conventional air-source heat pumps, we need to look at the flow temperature:

1. Traditional boilers: They send water to the radiators at around 70°C or 80°C. At that temperature, the radiators release a large amount of heat in a short time.
2. Conventional air-source heat pumps: Traditionally, heat pumps operated efficiently at low temperatures of 35°C – 45°C, ideal for underfloor heating. If they tried to reach 70°C, their efficiency (COP) dropped drastically and the equipment experienced excessive wear.

The result: If you installed a conventional air-source heat pump with old radiators, your home wouldn’t get warm enough on the coldest winter days.

The solution: High-temperature air-source heat pumps and R290 refrigerant

What has changed? The secret lies in the refrigerant. The latest-generation Ecoforest heat pumps, such as the ecoAIR PRO range, use R290 (propane).

This natural refrigerant makes it possible to achieve flow temperatures of up to 70°C or 75°C efficiently, even when outdoor temperatures are extreme.

Benefits of keeping your existing radiators:

• Immediate cost savings: You avoid the expense and disruption of installing underfloor heating or replacing every radiator with a low-temperature model.
• Quick installation: The switch from a boiler to a heat pump takes just a few days, using the existing pipework.
• Sustainability: By using R290, you not only save energy but also use a refrigerant with an almost negligible Global Warming Potential (GWP = 3).

Technical comparison: Standard vs. high-temperature air-source heat pumps

Is it as efficient as underfloor heating?

It’s important to be honest: an air-source heat pump is more efficient when it can deliver water at a lower temperature.

However, that doesn’t mean you won’t save money with radiators. Replacing an oil boiler with a high-temperature heat pump can reduce your energy bill by 60% to 70%. While underfloor heating may be the “ideal partner”, the combination of Ecoforest + old radiators is an exceptionally cost-effective solution and much more environmentally friendly than any fossil fuel.

What the system needs to work well

To make sure you can keep your radiators and stay comfortable at home, a qualified technician must check two things:

1. Radiator sizing: They must check whether the existing radiators have enough surface area to meet your home’s heating demand with the new heating curve.
2. Home insulation: If your home loses a lot of heat (old windows, uninsulated walls), any system will struggle. Sometimes, improving the insulation around roller shutter boxes helps more than installing a larger radiator.

Conclusion

Yes, it’s possible, and it’s a reality. You no longer have to choose between being cold and undertaking a major renovation at home. High-temperature air-source heat pumps have removed the last barrier preventing older homes from joining the renewable energy revolution.

If your home has traditional radiators and you want to switch to clean energy without the hassle, Ecoforest technology is designed for exactly your situation.