Air-to-water heat pumps: your guide to function, costs and benefits.

An air to water heat pump is an attractive option for homeowners who wish to embrace sustainable energy sources and reduce their energy costs over time. Especially for existing properties, it offers a practical heating solution, easily installed outdoors with minimal impact on the building's structure. In new builds, it provides an eco-friendly and cost-effective heating system.

Though the initial investment in an air to water heat pump might be higher compared to fossil fuel systems, the long-term savings from using free environmental heat make it worthwhile. Additionally, government incentives for heat pumps can ease the transition. Find more details in our subsidy guide.

Air to water heat pumps produce operational noise, but they generally operate quietly. Sound emissions vary by model, and legal regulations (TA Lärm) must be observed when installing an air to water heat pump, including specific protection zones and minimum distances from neighbouring properties.

Our Vaillant air to water heat pumps are perfect for densely populated areas due to their exceptionally quiet operation. The specially developed Sound Safe System ensures our heat pumps operate with minimal noise. In reduced power night mode, the sound level of our aroTHERM plus is just 29 dB(A) at three metres away—comparable to a whisper.

An air-source heat pump always requires at least an outdoor unit to operate. Monobloc systems combine all the components in a single outdoor unit. Connected pipes transfer water to the central heating system and hot water cylinder placed inside your home’s basement or utility room. This compact setup requires less financial invest, effort in installation and indoor space for installation compared to split systems – but with the entire heat transfer taking place outside, monoblocs are also a little less efficient.

In contrast to a monobloc, the components in a split system are separated into an indoor and an outdoor unit. They create most of the heat transfer within the walls of your home and thus operate with less heat loss and more efficiency. If you’re not limited in terms of space inside your home, increased installation costs of a split system are sure to pay off by means of more long-term efficiency.

An air-source heat pump may generate a certain operating noise. Therefore, the outdoor unit should be placed at least 3 metres away from your neighbours. Also, you should make sure not to place it right below your bedroom window and with enough surrounding space to enable sufficient air flow. The indoor unit is usually placed in the utility room and requires approximately 1 square-metre of space. You could even install the heat pump in apartments. In this case, approximately 2 square-metres of space for the outdoor unit are required. If you have chosen a monobloc system additional considerations regarding distance regulations apply.

The metric to determine the efficiency is the Seasonal Coefficient of Performance (SCOP), which is derived from the product's Coefficient of Performance (COP) and the respective climate conditions of your area. The COP describes the general ratio of consumed electricity to supplied heat. For example, a COP of 4 means that the heat pump supplies four times as much heating power as it requires in electricity. The SCOP then describes this value more precise for your respective area. Concludingly, the higher a heat pump’s SCOP, the more beneficial its installation will be and the higher the yearly COP which you can expect.

Yes, an air source heat pump can reverse its process and actively cool. Instead of extracting heat from the outside air and thus heating the rooms, it releases the heat from the rooms into the environment. With active cooling, you can reduce your room temperature by up to 3 °C. But be aware: not every underfloor heating system is suitable. It’s best to ask your local Vaillant installer about this.

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