What heat pump output do I need?

The output of a heat pump is determined by the heat loss of the house – in other words, how much heat the house loses at the lowest outdoor temperatures in the area. The floor area is only an indicative figure; a house of the same size can have very different losses depending on the insulation.

What it is based on

• the project and energy performance certificate – these often contain a heat loss calculation,
• the insulation of the walls, roof and floors, the type of windows,
• the heating system – underfloor heating or radiators and their water temperature,
• hot water consumption – the number of people and their habits,
• previous consumption – data on the consumption of gas or other fuel helps with the estimate.

Why not to oversize

A heat pump that is too large switches on and off often, which reduces efficiency and increases wear. It is also unnecessarily more expensive.

Why not to undersize

If the output is too low, the heat pump cannot keep up in frost and the backup electric heater switches on more often, which is less economical.

The bivalent point

The design also determines the temperature below which the heat pump needs help from a supplementary source. A good design looks for a balance between investment and running costs.

Why the output of the old boiler is not enough

Boilers are often more powerful than the house needs, because they also have to heat water quickly. If you chose a heat pump based on the boiler, it could be unnecessarily large. For estimating the heat demand, the previous fuel consumption is more useful, along with whether the house has since been insulated or the windows changed.

What to do if you do not have the documents

Older houses often have neither a project nor an energy performance certificate. In that case, the dimensions of the house, the composition of the walls and roof, the type of windows and the energy consumption in recent years all help. For a more complex house, a heat loss calculation by a specialist may make sense.

What to ask about a quote

• What data did you use to calculate the output?
• At what outdoor and water temperature does the output apply?
• When does the supplementary electric heater switch on?
• How was hot water taken into account?

An output stated under one set of conditions may not apply under another, so compare quotes under the same conditions. You will find an overview of models in the heat pump catalogue.

What to prepare

• project documentation or an energy performance certificate,
• information about the insulation and windows,
• the type of heating and the number of radiators,
• energy consumption over the recent period,
• the number of people in the household.

We will design the output

Based on the documents, we will propose a Daikin heat pump with the right output. Related: A Daikin heat pump for a family house: how to choose · A heat pump for an old house with radiators. Send us your documents.