Are you considering installing a heat pump? A large number of Samsø’s homes are heated using heat pumps, but why are they good to have and how do they work? Ole Hemmingsen is a blacksmith and plumber on Samsø, and he explains the basic workings of heat pumps.

What is a heat pump?

It’s a device that converts heat from the ground and pumps it throughout your house using either air or water. There are three types of heat pumps: geothermal heat, air-to-air, and air-to-water.

How do heat pumps work?

Using an evaporator, the heat pump absorbs energy from the environment, which causes the refrigerant to boil and evaporate. The steam is then compressed inside the compressor, the pressure increases and the temperature rises.
The refrigerant then releases its heat in the condenser, where it cools and turns back into a liquid that flows through the thermo-valve, where the process starts all over again. It’s in the condenser that the heat from the refrigerant is transferred to the home’s heat distribution system, either in the form of a water-conductor central heating system, or as heated air that can be blown into the house.

Why is a heat pump preferable to a fossil-fuel based heating source?

A heat pump has limited carbon dioxide (CO2) emissions because it gets its electricity from a fossil-free energy source. On top of this, you get 4-5 times the amount of energy out of a heat pump than that which goes into it, depending on which power source the heat pump is connected to. If it gets its energy from an old oil furnace, there may be negative energy utilization.

There are three kinds of heat pumps: How do you know which one to choose?

If you want to install a heat pump in a house where there is only electric heating, the air-to-air heat pump is ideal. This is especially true for holiday homes. If instead you have a central heating system with radiators, it’s perhaps better with a water-conducting air-to-water heat pump system, combined with geothermal heating. The latter is most commonly used, but requires a reasonably large area outside where hoses can be buried. Air-to-water is smart if you want heated floors, because you make optimal use of the surplus heat.

Why are there so many heat pumps particularly on Samsø?

There have been some good plumbers on the island who have understood the value of their products, given the increased attention paid to the negative impact of CO2 emissions on our environment. Eighty-percent of the year-round homes on Samsø that are not connected to district heating use heat pumps, and we have less than 200 oil furnaces left on the island.


Worth knowing about heat pumps:

Brands: There are myriad of brands produced in Denmark and abroad. Vølund, Boss, Danfoss and Panasonic all produce heat pumps, but which brand you choose depends on your needs and budget. You can buy heat pumps from your local plumbing installer.

Price estimates: Air-to-air pumps cost between 14-18,000 Danish kroner. (€1,900-2,400); air-to-water approximately 100,000 kroner (€13,500), while geothermal heat pumps costs about 125,000 kroner (€16,800). All prices include installation, which takes about 2-3 days depending on which solution you choose. Always remember to take advantage of the Danish tradesman deduction.

Savings: Compared to oil furnaces, you will approximately halve your annual heating costs. Furthermore, if your consumption is over 4,000 kilowatts, you can save around 62 øre (8 eurocents) per kilowatt through the public energy savings subsidy.

Maintenance: A heat pump should be inspected regularly and replaced every 10-15 years in order to stay in step with technological advances. Heat pumps are becoming more and more effective every year, and it is worth replacing them to achieve savings that newer models offer. Many also supplement their heat pump with a wood pellet stove, for which you can also receive subsidies.
Read more about heat pumps and their possibilities at


Engineer Michael Kristensen from Samsø Energy Academy and Samsø Municipality explains why a heat pump is a good investment:

1: Synergy: In the coming years, society is gearing up to phase out the use of fossil fuels, while the surplus heat from for example heat pumps is increasingly connected to the system for the benefit of others. New homes are not allowed to use oil furnaces, while the development of the sustainable energy sector is thriving. In other words, heat pumps along with other forms of green energy are the future, and will become increasingly cheaper, while fossil fuel sources will only become more expensive.

2: Fewer expenses: An oil furnace costs between 40-50,000 kr. (€5,400-6,700). While a heat pump is more expensive to buy, it is much cheaper to operate and has a life span of 20-30 years. On top of this, unlike an oil furnace, the heat pump does not require chimney sweeps or an annual costly inspection.

3: You save significantly more money on your heating bill: The savings are usually estimated between 30-50% on heating compared to an oil furnace, especially if the oil furnace is an older model. It’s frequently said that for every 1 kWh you invest in the heat pump, you get 4 kWh of heat.

4: You will have an easier time borrowing from the bank: Most banks can see the point of installing a less expensive heating system. If you borrow money for a heat pump, you should devise a budget demonstrating the significant savings accrued with such a system. Your installer/plumber can assist you.

5: Increased equity and a house that’s easier to sell: A heat pump provides an improvement on your house’s energy certification in one step, increasing the value of the house and making it easier to sell. In rural areas especially, homes tend to have oil furnaces which need replacing, and a new heating system will give a house a functional boost that will increase its value.

6: You get an overview of your energy consumption and needs: Before you decide whether or not to install a heat pump, it’s a good idea to investigate your family’s energy needs, habits and behaviour at home. Make a simple budget that shows the consumption of electricity, water and heat, and see if there are additional ways to save energy. It will pay off and give you extra money in your pocket on an annual basis, and will also show the bank that you can save up if necessary.

Remember: How effective a heat pump works for you depends on your home. If your house is modern and well insulated, a heat pump is an obvious choice. While an older house with small radiators and a single line system will probably require more insulation and thorough modernisation before the change is made. Also, take a look at your consumption, because the heat pumps are available in different strengths to match your everyday needs.
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