How does an air water heat pump work? Retrieves heat from the outdoor air

How does an air water heat pump work?

Function of the air / water heat pump

One air Water heat pump can in good conditions more than halve the electricity use for heating and hot water. It draws heat from the outdoor air and provides both heat and hot water, but can only be used in houses that have water-borne heating.

An air-to-water heat pump collects heat from the outdoor air and transfers it to a water-borne heating system. It should not be confused with an air-to-air heat pump that also takes heat from the outdoor air but spreads it via a fan in the house. An air source heat pump can not heat the water for taps and showers (domestic hot water).

An air water heat pump can more than halve the electricity use for heating and hot water in an electrically heated house, but it depends on where in the country you live and the temperature of the water that goes to the elements or to the floor heating. Air water heat pumps are therefore best suited in southern and central Sweden.

When it is really cold, there is no heat to pick up

Depending on how great the need for heat and hot water is, the heat pump can manage to deliver heat when it is -15 ° C outside without the need for any additional electricity, so-called peak heat. When it is really cold outside, it may be necessary to turn off the heat pump because the outdoor air then contains too little energy, unless the manufacturer has another recommendation, check the operating instructions.

Select the correct effect on the heat pump using the installer

It is important to choose a heat pump with the right power, get help from the installer. How much power on the heat pump you should choose depends, among other things, on where in the country you live and on the house's power needs. The power requirement is the number of kilowatts that must be supplied in order for you to get, for example, + 20 ° C indoors, at the lowest outdoor temperature.

The heat factor often shows the efficiency under certain conditions

When comparing different heat pumps, you should not just look at the heat factor, which shows the heat pump's efficiency and is a measure of how efficient the heat pump is. Often that figure only shows the heating factor under specific conditions, a certain outdoor temperature and a certain temperature of the water to the radiators. The heat factor varies during the year, among other things depending on how hot or cold it is outside and whether the heat pump is to provide both heat and hot water or only hot water. Therefore, find out that the heating factor you are comparing applies to the whole year and to the whole system.

On / off or speed control

There are two different ways to control a heat pump, either turn it on and off, or it is speed controlled. If you have a heat pump with an on / off control, this means that either the heat pump runs at full power or it is switched off, there are no intermediate positions. With a speed-controlled heat pump, the power is gradually adjusted depending on how the need for heat and hot water changes. When the need decreases, the speed decreases and thus the power of these heat pumps is normally more efficient. Manufacturers often use the English term on / off for on / off control and heat pumps with speed control are sometimes called "inverters".

The sound power level varies between different models

The sound from the fan that is located in the outdoor part of an air-to-water heat pump can be perceived as disturbing the surroundings. There are big differences between how much different models of heat pumps make noise. Avoid placing the outdoor area near the bedroom, the patio or near the plot boundary, towards the neighbors. A difference in sound power level of 10 dB (A) is perceived as a doubling. It is not only the number of decibels but also the character of the sound that matters whether it is perceived as disturbing or not. A tip is to go and listen to a number of heat pumps that are already installed before you decide. In 2015, there will be a requirement for a maximum noise level of 70 dB (A) outdoors, for heat pumps between 6 and 12 kW, and the noise level will also be shown on the energy label. Ask today about how much the heat pump sounds.

Talk to the neighbors and the municipality

Feel free to discuss with your closest neighbors and agree on where the heat pump should be located. If the neighbors feel that the noise is disturbing, you may in the worst case be forced to turn off the heat pump, if the noise level exceeds the current limit values ​​at the plot boundary. A tip is that you contact the environmental office in your municipality before you get a heat pump and find out what applies to air-to-water heat pumps where you live.

Refrigerants may need to be controlled

All tested heat pumps use fluorinated refrigerants so-called F-gases. They do not deplete the ozone layer, but can affect the greenhouse effect. Heat pumps that contain three kilograms of greenhouse gases or more and that are not hermetically sealed must be checked once a year, so that they do not leak greenhouse gases. However, there are exceptions for heat pumps that are hermetically sealed and that contain less than six kilograms of greenhouse gases. There must be a label on the heat pump that shows if it is hermetically sealed.

The defrosting of the outdoor part must not form an ice street or damage the house foundation

Heat pumps that draw energy from the outdoor air must be defrosted regularly if it is colder than + 7 ° C and at higher outdoor temperatures the water in the outdoor air condenses. There will be large amounts of water during a year, 2,000 liters of water or more. Be sure to divert or collect the defrost water so that no ice street forms at the front door or so that the foundation of the house or the vegetation in the garden is damaged.

Compare quotes from several installers

Before you decide, you should receive quotes from several installers where it must be clear what is included in the price and the conditions for delivery, operation and maintenance. It is good if you yourself have the opportunity to read the heat pump's energy use and operating times. The offer must also include commissioning and adjustment of the new heating system. The installer must also give you a calculation of how much energy savings will be in your house compared to before installation. Also remember to compare warranties and other terms.

Try to reduce the need for heat and hot water

Before you get a heat pump, it is good if you can reduce the need for heat and hot water so that you can choose a smaller heat pump with lower power, it is often cheaper and the heating system if the temperature in the elements (radiators) or underfloor heating can be lowered. Additional insulation or switching to energy-efficient windows are examples of measures that reduce the need for heating.

To reduce the need for hot water, it is wise to review your shower habits and get more efficient shower nozzles. A rule of thumb is that the heat pump should cover about 90 percent of the house's annual need for heating and hot water. The installer sometimes says that the heat pump is dimensioned to handle 60-70 percent of the maximum power requirement, which is the same thing.

Upcoming requirements for energy labeling and ecodesign

Air water heat pumps will receive energy labeling, which makes it easier for consumers to choose an energy-efficient product that does not make so much noise. Systems such as a heat pump with a solar panel will also be energy-labeled. These extra efficient systems benefit from the new energy label. The requirements for energy efficiency will enter into force in 2015 and be tightened two years later.

The new legal requirements apply to all boilers and heat pumps for water-borne heating systems, up to 400 kW. The least efficient heat pumps with the highest operating costs, noise levels and environmental impact will thus no longer be sold.

Air / Water

We install and service air / water heat pumps of various brands. Contact us and we will help with dimensioning, suggestions for placement, etc. We are happy to make a savings calculation for you.

    How does an air water heat pump work?