Heat Pump Heating in Houses and Flats: Types, Planning, Installation

The heat pump is today the first choice both for modernising the heating of family houses and for new builds – but it only works well as a properly sized system: with output matched to the building, suitable heat emitters and enough electrical capacity. Types, planning, plant room, controls – for renovation and new houses alike.

A heat pump is not a “miracle boiler”, it is physics: it takes heat from the outside air (or the ground) and uses electricity to “pump” it up to a higher temperature. Over a year, it produces on average 3–4 kWh of heat from 1 kWh of electricity (this is what the SCOP value measures) – which is why it is cheaper to run than gas, and especially than direct electric heating. Its efficiency, however, depends on how low a flow temperature it can heat with – and this is where insulation and underfloor heating come in.

Summary

• For family houses the air-to-water heat pump is the most widespread; in flats and as supplementary heating, air-to-air (air conditioning) plays the main role.
• A heat pump is efficient at a low (30–40 °C) flow temperature – which is why it is paired with underfloor heating or large-surface radiators.
• Sizing is based on a heat load calculation: an oversized unit is just as much a mistake as an undersized one.
• In a renovation the order is: insulation and windows first, then a heat pump chosen for the reduced heat demand.
• What it needs: enough electrical capacity (often 3-phase), a well-placed outdoor unit, a plant room or wall-mounted indoor unit, and well-thought-out controls.
• The heat pump is among the eligible works of the energy grant announced for 2027.

Types: which heat pump goes where?

In the Hungarian climate and for an average family house, an air-to-water system gives the best value for money – so this is mainly what we discuss from here on. The choice between a monobloc (everything in the outdoor unit, with water pipes) and a split version (outdoor + indoor unit, with refrigerant pipes) depends on the site and the installer’s certification.

Why underfloor heating is the heat pump’s natural partner

A heat pump’s efficiency depends on the flow temperature: the smaller the difference between the outside air and the heating water, the less electricity it uses. Underfloor heating works with water at 30–35 °C – giving the same sense of warmth as a radiator at 55–60 °C. That is why the most common and best-performing combination is an air-to-water heat pump + underfloor heating.

• In a new build this is now practically the default: the underfloor heating goes into the screed, with a circuit per room and a manifold.
• In a renovation underfloor heating can be installed if the floor build-up is being redone anyway (full renovation) – this means extra layer thickness and drying time. If the floor stays, the solution is a larger, low-temperature radiator or a fan coil: some of the existing radiators may be enough at 45–55 °C if the house has been insulated in the meantime – this is decided by a heating calculation, not an estimate.
• A mixed solution is also common: underfloor heating on the ground floor, radiators or fan coils upstairs, a towel rail in the bathroom.
• Cooling: in summer an air-to-water system can also provide moderate cooling (floor or wall cooling, fan coils); floor cooling requires dew-point monitoring.

Planning and sizing: this is where everything is decided

1. Heat load calculation. The starting point is the building’s design heat load (kW), based on insulation, windows and air exchange. In a renovation the calculation must be for the planned condition: insulation first, then choosing the unit – the other way round you end up with an oversized unit that cycles expensively. (On the order of work: our house renovation guide.)
2. Choosing the unit. Besides the rated output, what matters is the SCOP (seasonal efficiency) and the output delivered at −7 °C. With an inverter unit the modulation range counts: a good unit follows demand between 20 and 100%.
3. Electrical background. The heat pump of an average family house draws 1–4 kW of electrical power; because of its starting current and the other loads (induction hob, EV), a 3-phase supply and a capacity upgrade are often needed – this has to be started with the network operator in good time. (More detail in our article on the wiring of old houses.) It is also worth finding out about discounted electricity tariffs (e.g. the H tariff).
4. Location of the outdoor unit. A well-ventilated spot protected from snow, on a stable base or bracket, with condensate drainage (it can ice up in winter!). Keep the noise level towards the neighbours in mind – it should not go near a bedroom window or the plot boundary; on a block of flats, placing it on the façade requires consent.
5. Hot water and buffer. Domestic hot water needs an indirect cylinder (typically 200–300 l), and the heating circuit – depending on the unit and the system – a buffer tank. Their space requirement has to be allowed for when planning the plant room.

The plant room: where does the system go?

In a new house the “plant room” is a 3–5 m² utility/technical room: indoor unit or wall-mounted hydraulic module, hot water cylinder, buffer, manifold, electrical protection – ideally together with the washing machine and the domestic water pump. In a renovation the old boiler room, a storeroom or a corner of the garage takes on this role; with a wall-mounted indoor unit and compact towers (with a built-in hot water cylinder) 1–2 m² can be enough. What it needs: water and drain connections (for condensate and blow-off), an electrical supply, a frost-free environment and access for servicing.

When replacing a gas boiler you also need to think about what happens to the gas supply: if cooking also switches to induction, the gas meter can be removed and the standing charge disappears – this is part of the payback calculation.

Controls: smart means you rarely have to intervene

• Weather-compensated control: the unit sets the flow temperature according to the outside temperature, following a heating curve – this is the basis of efficient operation, not switching the thermostat on and off.
• Room control: zone thermostats connected to the manifold circuits; underfloor heating is slow to respond, so steady, low-level operation is the right strategy, not big daily swings up and down.
• Remote monitoring: today’s units can be operated over wi-fi from an app, with error messages and consumption monitoring remotely. Most manufacturers can be integrated into a smart home (e.g. operation coordinated with solar panels, following tariff steps) – we wrote about this in our smart home article.
• With solar panels: a heat pump + solar panel combination significantly reduces heating costs over the year; the billing arrangement (gross/net metering) needs to be checked with the provider.

A heat pump is not good because of the unit – it is good because of the system it is built into.

Renovation or new build: how do the two situations differ?

In a renovation the most important decision is not the brand but the order. A heat pump put on an uninsulated house works with a high flow temperature and poor efficiency, and the electricity bill eats up the savings – we have already covered this mistake in our article the secret of an energy-efficient house. The good news: the announced list of works for the 2027 energy grant includes insulation, window replacement and the heat pump together – exactly the package with which the 30% energy saving can reliably be achieved.

A heat pump system from TeleHome

TeleHome carries out plumbing, heating and heat pump installation under one roof, together with the other trades of the renovation or build: heat load calculation, electrical capacity upgrade, underfloor heating or radiator replacement, plant room fit-out and commissioning. The entire building services of our reference house in Érd are based on a heat pump heating and cooling system, with provision for solar panels and an EV charger. Request a survey – in a renovation we design the system together with the insulation and the electrical network.

Frequently asked questions

Is a heat pump suitable for a radiator system?

Yes, if the radiators have enough surface area for the lower (45–55 °C) flow temperature – after insulation this is often the case, if necessary by replacing a few radiators. This has to be confirmed by a heating calculation.

Does an air-to-water heat pump work at −10 to −15 °C?

Yes, modern units keep heating down to −20 °C, with decreasing efficiency; that is exactly why the sizing is done for the cold days. For extreme cold the units have a built-in electric backup heater.

Does a heat pump need a 3-phase supply?

Smaller units also run on a single phase, but for a family house – especially alongside an induction hob, air conditioning or an EV charger – a 3-phase supply and a capacity upgrade are usually justified. Dealing with the network operator can take weeks, so it needs to be started in good time.

Heat pump or condensing gas boiler?

In a well-insulated house with underfloor heating, the running costs of a heat pump are typically lower, and it can cool as well. In a poorly insulated house with radiators, insulation pays off first – after that it is worth recalculating. The decision is best made with a payback calculation, not a general rule.

Can a flat have heat pump heating too?

Yes: the most common solution is air-to-air (multi-split air conditioning), which both heats and cools. Placing the outdoor unit on a block of flats requires consent. An air-to-water system is rarer in a flat, but it can be done in a flat with its own heating and a balcony or garden.

Related services: Plumbing, gas, heating, heat pumps · Electrical installation, meter point installation · House renovation and modernisation · House building – overview

Related articles: The secret of an energy-efficient house: it is not the heat pump · Facade insulation on a family house · Wekerle Plus energy renovation grant