Choosing a heat pump is one of the most important decisions you can make for the comfort and costs in your home. This is not a purchase “by sight”, nor a decision that should be based only on a brand or advertising. A properly selected system means warmth, savings and many years of trouble-free operation. The wrong choice – high bills, inconvenience and unnecessary repairs.
In this first part, we will show you what really stands behind the correct choice of a heat pump – with specific examples, values and mistakes that we most often see with our clients at Niko Term.
Selection starts with the right sizing
The first and most important step is to calculate the required power. This is the foundation of any heating system. If it is wrong, all other components start to work inefficiently. The general rule is as follows:
- A well-insulated house, new construction, quality joinery and external insulation
→ 50–60 W/sq m - An older building, without good insulation
→ 80–100 W/sq m
A real-life example:
- A 120 sq m house, well insulated → about 7 kW are needed
- The same house, but without insulation → the required power jumps to 10–12 kW
This is not just a difference in numbers. Here the machine and the price will already be different. There will also be a difference in the monthly electricity bills. Last but not least, there will also be a difference in the way the system works on a daily basis.
A weak heat pump will work continuously and will not reach the required temperature. Too powerful will turn on and off frequently, consume more electricity and shorten the life of the compressor.
That’s why at Niko Therm we always do a thermal calculation before a quote – not for the “professional look”, but because this guarantees an accurate, balanced and efficient system.
What kind of heating system are you planning (or have)?
The second key factor is the type of heating system. Not only the choice of heat pump, but also its efficiency depends on it.
Underfloor heating – the ideal combination
Underfloor heating works with a low water temperature – around 30–35°C. This allows the heat pump to operate in its most efficient mode with a coefficient of performance (COP) between 4 and 5.
What does this mean in practice?
If you pay 100 BGN for electricity, you get heat equivalent to 400–500 BGN.
Radiators – a completely possible solution
If your home has radiators, this is not a problem. It is simply important to choose the right machine.
- Radiators usually require 40–60°C
- The COP in this mode is around 3–3.5
- This is again twice as efficient as an electric boiler
In older installations with small radiators, a high-temperature heat pump can be used, which can easily deliver 65°C.
With newer and well-sized radiators, the low-temperature heat pump remains the more economical option.
The buffer tank – an often underestimated but key component
The third extremely important element is the buffer tank. Many people consider it unnecessary, but in reality it is key to:
- smooth operation
- longer compressor life
- lower electricity consumption
The recommendation is:
7–10 liters of buffer for every 1 kW of power
Example:
- 10 kW heat pump → 70–100 liters of buffer
The buffer tank extends the operating cycles, eliminates frequent switching on and protects the system from excessive load. This directly saves electricity and reduces wear.
One system – three functions
If fan coils are added to the system, the heat pump can provide:
heating in winter
cooling in summer
domestic hot water all year round
There is no universal heat pump – there is a properly selected one
The right heat pump is a combination of:
- accurate calculations
- understanding your lifestyle
- analysis of the existing system
At Niko Term we always start with the questions:
- how big is the home
- how many people live in it
- how is it currently heated
- what comfort are you looking for
Only then do we select a solution that will work economically, reliably and in the long term.
The heat pump – comfort 365 days a year
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👉 In the second part, we will look at real mistakes, incorrect configurations and how to avoid costly compromises during selection and installation.
If you are unsure about how much power you need or whether your current system is suitable – contact us. We will help you choose the best solution for your home.