Air-to-water heat pumpNo drilling, with sun.

An air-to-water heat pump draws heat from the outside air and passes it to your heating system and your hot water. Even at sub-zero temperatures, the air still holds usable energy. The unit needs electricity for this, but delivers several times as much as heat.

It is the most common heat pump in Switzerland. The reason: it needs no drilling, is quick to install and suits both new builds and existing buildings. Together with a solar system, it covers part of its electricity needs from your own roof.

You will find an overview of all systems under heat pump. This page is only about the air-to-water type.

How does an air-to-water heat pump work?

A fan draws outside air through an evaporator. A refrigerant absorbs the heat, and a compressor raises the temperature. In the condenser, the heat passes to the heating water.

The measure of efficiency is the seasonal performance factor (SPF, JAZ). It tells you how many kilowatt-hours of heat the unit delivers per kilowatt-hour of electricity over the year. For air-to-water units, it is around 3 to 4. The lower the flow temperature of your heating system, the better the value.

Indoors or outdoors?

Where to put the unit is the most important planning question.

Option	How it works	Suitable when
Outdoor siting (monobloc)	The whole unit stands outside. Two pipes lead into the house.	There is space in the garden or by the house wall.
Split unit	Evaporator outside, hydraulics and storage tank in the house.	There is little space outside, or the hydraulics inside should be frost-protected.
Indoor siting	The unit stands in the house, air comes through ducts.	A suitable room and wall openings are available.

There are also practical points: keeping it clear of snow, condensate drainage, access for servicing and the view from your seating area. We look at the site during the site visit and show you what is possible.

How loud is the heat pump? Noise protection and neighbours

Air-to-water units make noise. The fan and compressor produce a level that falls with distance. On your own property this is rarely a problem. At the neighbour’s, the limit values of the Noise Abatement Ordinance apply.

This is how we proceed:

1. We choose a quiet model and, where useful, a night mode with reduced output.
2. We choose the site so that bedroom windows, terraces and neighbouring plots are not in the direction of the sound.
3. We prepare the noise protection assessment if your commune requires it.

We would rather clear up noise concerns before the purchase than after. So we calculate the level already during planning.

Air-to-water heat pump with solar system

The heat pump uses electricity, the solar system produces it. This fits especially well in the shoulder seasons: in spring and autumn, the heat pump heats with solar power during the day.

• Hot water: The storage tank is heated during sunny hours.
• Self-consumption: Electricity from the roof is more likely to be used by you, rather than flowing into the grid.
• Running costs: Every kilowatt-hour you use yourself is one you do not have to buy.
• Extension: A battery storage unit shifts solar power into the evening.

In winter, the system delivers less and the heat pump needs more. Then part of the electricity comes from the grid. So we do not size the system for the summer, but for your total demand.

Who is the air-to-water heat pump suitable for?

It fits in most cases, but not every one. It is well suited to:

• Single-family homes, including older ones, if the flow temperature is not too high.
• Replacing an oil or gas heating system, where there is no space or no permit for drilling.
• New builds with underfloor heating, where very low flow temperatures are possible.
• Plots with space for an outdoor unit and enough distance from the neighbours.

It gets tricky on very narrow terraced-house plots, with high flow temperatures without adjustment, or where the noise towards the neighbour is hard to limit. Then we recommend a different siting or a different technology. We will tell you openly.

What role does the flow temperature play?

The lower the temperature your heating system works at, the less electricity the heat pump needs. Underfloor heating manages with about 30 to 35 degrees, older radiators often need more. At the site visit, we check what temperature your house really needs on cold days. Often it can be lowered with a few changes, for example a few larger radiators or a clean hydraulic adjustment.

What does an air-to-water heat pump cost?

For a single-family home, the total cost for the unit, storage tank, installation, removal of the old heating and electrical work is roughly CHF 30,000 to 50,000, before subsidies. This is a guide, not a price.

What moves the price up or down:

• Heating output: A larger house needs a more powerful unit.
• Removal: Taking out the oil tank, chimney and boiler takes time.
• Heating system: If radiators have to be replaced, costs are added.
• Electrics: A new meter cabinet or a stronger supply line is needed in some houses.
• Siting: Foundations, ducts or long pipes make the project more expensive.

You receive the binding quote within 72 hours of the site visit. It contains all items, the subsidies and the expected running costs.

Subsidies

Replacing a fossil heating system with a heat pump is subsidised, primarily through the cantonal buildings programme. Some communes and energy suppliers pay on top. The amount, conditions and deadlines differ from canton to canton.

Often the application must be made before work starts. We handle the subsidy application for replacing your heating system as part of the service. The subsidies can be pre-financed on request.

How the installation runs

1. Enquiry and site visit: We check the heating, radiators, site and electrical system. Free of charge.
2. Quote within 72 hours: binding, with subsidies.
3. Applications: Subsidy application, notification to the commune, noise protection assessment, registration with the grid operator.
4. Removal: The old heating and tank are taken out and disposed of.
5. Installation: Unit, storage tank, hydraulics and electrics. For a single-family home, this often takes only a few days.
6. Commissioning: We set the heating curve and explain how to use the system.

Planning through to commissioning is in our hands, from one source.

Air-to-water heat pump in your region

Our locations are in Zumikon ZH and Lachen SZ. We build across German-speaking Switzerland. Noise rules and subsidy programmes differ by canton and commune. We know the procedures and tell you at the site visit what applies at your address.

If you have a plot with good space in the ground, it is worth looking at the ground-source heat pump. We calculate both options for you.