How big a heat pump do I need?

How to choose the right heat pump for your home?

When choosing a heat pump, there are a number of factors to consider. It is important that not only the brand and type, but also the size and capacity of the unit match our needs. In this article, we will look in particular at air-to-water heat pumps, as they are the most common in Hungary.

During the preparatory steps, it is worth browsing product catalogues, official brand websites or dealers' websites to learn about the features and characteristics of different brands and types. At ZPK Solar, for example, we recommend Fujitsu air-to-water heat pumps for their reliability, quiet operation and ease of installation.

How big a heat pump do I need?

Choosing the right heat pump size is a critical step in the design of a heating system. The performance of the heat pump is determined by the heat demand of your home, the size of the building, its insulation and environmental factors. Key considerations include the type of heat transfer surface of the building, the type and temperature of the current heating system, and the size and intended use of the building. Based on this information, an expert can determine exactly how much heat pump you need.

Where can I find help with choosing a heat pump?

Many websites offer calculation options to help you choose the right heat pump size. These calculators usually give an estimate based on basic data, but don't forget that the cost of the mechanical design must be added to the total cost. This includes the mechanical installation and the materials required. The cost of mechanical installation varies and depends on the complexity of the installation.

The average cost of mechanical installation ranges from around HUF 800 000 to HUF 1 200 000, but for more complex installations this amount can be higher. It is important to note that it is always worth consulting an expert when designing the heating system and choosing the size of the heat pump.

There are many types of heat pumps, but three main types are discussed below:

1. Geothermal heat pump (ground-to-water heat pump) This is perhaps the best known type of geothermal heat pump. As the name suggests, these heat pumps use geothermal energy. There are two main types: ground source and ground source heat pumps.

Ground-source heat pump: in this system, pipes are laid horizontally in the ground at a depth of 1.5 metres. The sun heats this soil layer and the system extracts heat from it. This type not only uses the heat from the sun, but also the heat from rainwater seeping into the ground. However, it is worth considering this type, as it is not possible to build or concrete over the ground collector.

Ground source heat pump: the installation of this type depends on the local geological conditions. It is drilled vertically to a depth of up to 80-120 metres where the probe is located and the refrigerant flows inside it.

Disadvantages: Installation and deployment can be costly due to drilling and excavation, and payback can take longer.

Benefits: The COP (coefficient of performance) is a high value (between 4-5), which indicates how much kW of heat energy the heat pump can produce using 1 kW of electricity. The higher the COP value, the more efficient the heat pump.

 

2. Water-to-water heat pumps (dug or drilled wells, open water type) This type of heat pump is the most optimal in terms of usable energy, as it is highly efficient due to the high groundwater temperature. The efficiency of the system does not change significantly with the onset of cold weather, as the groundwater temperature is constant.

This type of heat pump requires two wells (source and sink), spaced at least 15 metres apart. Before installing the system, it is recommended that a test borehole is drilled to check that there is sufficient quality water for the system.

Disadvantages: Installation requires a lot of preparation, such as drilling wells, and not all areas have sufficient water to run the system.

Benefits: Water-to-water heat pumps have the highest COP (between 5 and 7) of all heat pumps, so no other heating solution is needed and they are also suitable for passive cooling.

 

3. Air-to-water heat pump Air-to-water heat pumps are among the simplest types. These heat pumps extract heat from the air and use it in the heating system. Although their COP value (3-4) is generally lower than that of geothermal heat pumps, they can be a good choice for domestic weather conditions.

Disadvantages: The cold air can cause the heat pump to be less efficient and more electricity may be needed for heating in cold weather.

Benefits: The installation costs are lower and no further preparation is required, provided that the electricity supply is secured. In addition, it can be used with the existing heating system.

 

What information should be prepared before the consultation?

• Current heating system type (gas boiler, mixed fuel boiler, electric boiler, other)
• Type of heating surface of the current heating system (cast iron radiator, panel radiator, underfloor heating, ceiling heating, fancoil)
• Current heating system water temperature (˘C) - DHW flow rate
• In the case of DHW production, how many people would you produce domestic hot water for?
• Building plan, mechanical description
• Is there an "engine room"/mechanical room available? If so, how large (m2)?
• Size of heated space?
• Consumption data for existing heating system (gas m3 for gas boiler, kWh for electric boiler)
• Energy certificate within one year / energy calculation available for new build property?

Why is it important to choose the right heat pump performance?

Getting the heat pump performance right is key. If the heat pump is undersized, the system can be overloaded and the heat pump will have to run at high speeds all the time, which can reduce its lifetime and increase consumption. At the same time, an oversized heat pump can also cause problems as it will be unnecessarily powerful and therefore not energy efficient.

Choosing the right heat pump performance is therefore key to optimal operation and return on investment.

 

Request our free survey and we will find the best solution for you!