Retrofitting a heat pump: requirements and benefits

Retrofit a heat pump and reap the rewards

A heat pump heating system can provide three to five kilowatt hours of heat with just one kilowatt hour of electricity. That is achieved through a technical process in which a refrigerant is repeatedly vaporised, compressed and expanded. This environmental heating system operates entirely without combustion. There is no need for a chimney or flue gas inspections. It consumes no fossil fuels itself and produces no flue gases or harmful emissions. Together with the high efficiency of the heating appliances, this ensures sustainable low heating costs. Ancillary costs are also reduced, as the technology is low-maintenance and no chimney is required. 

You benefit in the following ways when you retrofit a heat pump:

• Economical heating with renewable energy from the air
• No direct emissions of CO₂ or air pollutants
• Low-maintenance, proven and reliable heating technology
• Lower heating costs thanks to high operating efficiency
• No chimney and flue gas inspections means reduced ancillary costs
• Space saving without fuel oil tank or gas connection in the building
• Heating and cooling possible with one central system

Requirements for retrofitting a heat pump

In principle, a heat pump heating system can be installed in almost any building. However, there are a few points to note to ensure that the system works efficiently and economically. The reason for this is the special way it works. The environmental energy vaporises a refrigerant. A compressor raises the temperature with the pressure, and the medium releases heat to the heating system. The greater the difference between the source or ambient temperature and the heating water, the more power the compressor consumes. If you want to retrofit a Carrier heat pump and save on heating costs, you should limit this temperature rise. Here's an overview of how you can achieve this: 

• Balance the heating system and optimise the flow temperature: In an unbalanced heating system, the temperature of the heating water is often slightly too high. All rooms can then be supplied with heat. However, environmental heating consumes more electricity. Hydronic balancing is therefore the first requirement when retrofitting a heat pump. This is usually carried out by the contractor as part of the installation.

• Retrofit large radiators or area heating systems: For a small radiator to heat a large space, it needs to operate at a very high temperature. There is no other way to provide sufficient heat. However, the high temperature results in a large temperature rise and therefore greater power consumption by the environmental heating system. You should replace small radiators with larger ones or retrofit underfloor heating with the heat pump in order to keep heating costs low. 

• Install thermal insulation or replace windows: Uninsulated houses with old windows lose a lot of heat to the surroundings in winter. A high heating output is required to compensate for the loss and maintain optimum room temperatures. Together with compact heating surfaces, this means a high flow temperature is needed. If you want to retrofit a heat pump and save on heating costs, it is therefore often worth replacing your windows and/or insulating your home. In many cases, you can even tackle some of these measures yourself, such as attic and basement ceiling insulation. This doesn't cost much and already brings tangible benefits.

Important to know: You can retrofit a heat pump if the flow temperature of the heating system can be limited to around 50 to 55 degrees Celsius. For every degree Celsius less, heating costs fall by one to two percent.

Upgrading an existing heating system: Hybrid solution in older buildings

If the conditions are not ideal, you can also retrofit an existing oil or gas heating system with a heat pump. The latter can be easily integrated into your current heating system. It can provide sufficient heat by itself to ensure cosy, warm rooms for large parts of the year, with the fossil fuel heating system only kicking in on very cold winter days. By reducing your fossil fuel consumption in this way, you can easily lower your heating costs. If your existing heating system is already outdated, you are also permitted under current legislation to combine a new gas heating system with a Carrier heat pump. However, the environmental heating system must cover 30 to 40 percent of the building heating load, depending on the operating mode.

Hybrid solution with heat pump and gas heating system –– not always the right choice

It doesn't always make sense to retrofit a new or existing gas heating system with a heat pump. This is because there are some additional costs associated with gas heating systems that must be observed when comparing the figures. These include meter costs, gas standing charges and outlays for maintenance and flue gas inspections. Remove the fossil component and all of these additional costs disappear. That's why retrofitting a heat pump without a gas heating system can pay off even if the expected heating costs are somewhat higher than with a hybrid solution.