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What are the disadvantages of a heat pump?

Last updated on 16 March 2021

Heat pumps are a growing success. However, they are not necessarily the right choice in every situation.  Here’s a 'true or false’ to update you on the disadvantages commonly associated with this type of heating.

It’s expensive to install a heat pump

TRUE. They cost considerably more than a gas installation. Nevertheless, grants are available to reduce the purchasing cost, which is not the case with gas installations. However, even with such grants, the heat pump is still at least 20% more expensive.

On the other hand, a heat pump recovers its cost during its life, due to its low operating costs. Particularly when combined with solar panels. At the time of investment, it’s true that the bill is higher.

Not suitable for every home

TRUE. If your home is poorly insulated and your budget is limited, start with insulation and forget heat pumps for the moment. In doing so, even your old heating will give you some satisfaction by consuming less. And the savings you make will help you to fund a heat pump installation in the future.

Heat pumps end up more expensive because electricity is more expensive than gas

FALSE. It’s true that electricity (at approx. € 0.25/kWh) costs more than gas (at approx. (€0.06/kWh). However, at the end of the day, this difference disappears since the return on the heat pump is 3 times more than that of a gas boiler:

  • when a boiler consumes 1 kWh of gas, it provides about 0.95 kWh of heat, if its yield is at 95%.
  • when a heat pump consumes 1 kWh of electricity, it provides about 3 kWh of heat (or less if it’s cold).
Where does this difference come from? The heat pump extracts the sun’s free heat from the environment (water, air, soil). Heat pumps consume 3 times less energy than a gas pump to produce the same quantity of heat.

More grey (hidden) energy is consumed 

TRUE and FALSE. In order to produce the electricity required for the heat pump, thermal power stations consume about 2.5 to 3 times as much primary fossil energy (gas, petrol, coal). In this case, electricity will end up creating more pollution than gas or petrol.

However, there are two pieces of good news:

  • electricity is increasingly being produced with solar or wind power, or other renewable sources, as well as nuclear power, which does not produce CO2
  • the basic principle in the heat pump is that it consumes about 3 times less energy to produce the same quantity of heat as a boiler. This more or less compensates the fossil energy consumed in producing the electricity.

You can also limit the electrical consumption of your heat pump by applying these tips.

The yield declines when the weather is cold 

TRUE. To be more precise, it’s the 'performance coefficient' that declines. The average is 3: 1 kWh electricity consumed for every 3 kWh of heat produced.
The colder it gets, the more the heat pump must work, and therefore consume, in order to continue extracting heat from a source which is growing colder. This is an unavoidable fact of life.

  • The electrical consumption will double if the outside temperature is between +°2C and -7°C.
  • At temperatures below -20°C, heat pumps with an air (air/water or air/air) exchanger are unable to operate, as the refrigerating agent they contain can no longer evaporate. This is why heat pumps are equipped with an additional electric heater that takes over when the system fails to gather enough external energy to heat the water to the desired temperature.

However, it’s important to put the problem into perspective:

  • in Belgium, the average annual temperature is 9.8°C (7.5°C for the Hautes Fagnes and 11°C in the Campine region). This means that the heat pump operates in optimum conditions for most of the year.
  • the minimum figures vary between -10 and -15°C depending on the regions, for a total of 2 to 12 days a year. In our area with its temperate maritime climate, periods of extreme cold are exceptional and very short. And even less common in urban districts.
  •  An optional space heater is enough to ensure basic comfort during a very cold spell and remains an interesting addition throughout the season in the case of e.g. a wood/pellet stove.

My electricity invoice will double 

Sometimes TRUE. However, the gas bill will be lower. Also, the maintenance is cheaper. And if you have solar panels, you can compensate at least some of this additional consumption.

The radiators will need replacing

TRUE, if you’re replacing your boiler with a heat pump. Indeed, this operates at a lower temperature (25 to 28°C, compared to 45-55°C for a gas condensing boiler) and requires larger exchange surfaces.

Having said that, it’s not ideal to replace a boiler with a heat pump in the case of existing central heating.

Installing a heat pump when doing renovations: impossible

FALSE. It is often possible, provided the house is well insulated and hermetic (with ventilation!). However, it is not possible to use every kind of heat pump in this case.

When carrying out major renovation, it is possible to envisage floor or wall heating, as the perfect addition to a heat pump.

A heat pump in an apartment: impossible

FALSE. You just have to pay attention to a few particularities of the situation to choose the most suitable solution.

Heat pumps are very noisy

TRUE. Outdoors at least, and that may annoy you or disturb the neighbours. It’s the same kind of annoying noise as the external unit in an air-conditioning system.

This does not apply indoors: a heat pump air/air (injecting hot air) will be no noisier than mechanical ventilation.

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