Air-to-Water Heat Pump and Dry Underfloor Heating Retrofit in the Netherlands

Modernising an older home often begins with a simple ambition: improve everyday comfort without losing the details that give the property its personality.

In this Dutch home, an existing timber floor extended through the open-plan kitchen, dining room and living area. Beneath the familiar interior, however, the heating system needed to be brought up to modern standards. The goal was to upgrade the heating while preserving the original character of the house.

Completed in May 2026, the renovation combined an air-to-water heat pump with approximately 60–70 m² of low-profile hydronic underfloor heating. The system was designed for space heating only; domestic hot water was not included.

Working within an existing property meant that floor height, staircase connections, door thresholds, kitchen furniture and the original subfloor all had to be considered. A lightweight radiant floor heating system provided a practical way to introduce modern heating without installing a thick screed construction.

Once concealed beneath the new wood-effect herringbone floor, the heating installation became almost invisible. What remained was a cohesive interior that combined modern heating technology with the established character of the home.

Project Overview

• Location: Netherlands
• Project type: Existing house renovation
• Installation date: May 2026
• Heated area: Approximately 60–70 m²
• Heat source: Air-to-water heat pump
• Heat distribution: Low-profile dry underfloor heating
• Application: Space heating only
• Domestic hot water: Not included
• Rooms covered: Kitchen, dining and living areas
• Floor finish: Wood-effect herringbone flooring

The project created a space-heating system suitable for use with an [air-to-water heat pump] https://www.nordthermglobal.com/products/r290-air-to-water-split-heat-pump-for-heating-cooling-and-hot-water while retaining the home’s existing layout and visual character.

1. The Challenge of Retrofitting an Existing Home

Unlike a new building, an existing house already has fixed floor levels, doors, stairs, kitchen furniture and adjoining surfaces. The heating installation therefore had to adapt to the property rather than being designed as part of a completely new structure.

The original timber floor first had to be removed so that the underlying surface could be inspected. Available installation height was also limited: a substantial increase in floor level could have complicated the staircase, door thresholds and kitchen connections.

A modular, low-profile system was selected so that the heating circuits could follow the existing layout and avoid areas where coverage was unnecessary.

Read our guide to https://www.nordthermglobal.com/blog/can-underfloor-heating-be-installed-in-an-existing-house-a-retrofit-guide

2. Removing the Old Floor

The first stage was to remove the existing timber flooring. This exposed the subfloor and allowed the installer to identify uneven sections, remaining adhesive, loose material and areas that required further preparation.

The timber fragments and installation debris were cleared before the surface was cleaned. Although this work is hidden in the completed interior, it creates the foundation for a stable floor construction.

A properly prepared base helps the heating panels remain level and supports the final floor above. Different substrates may require different preparation methods.

3. Creating a Level Base

After the original floor was removed, the substrate was levelled to create a suitable base for the heating panels.

Because the selected system does not rely on a thick layer of flowing screed, the supporting surface needed to be firm and reasonably even. Particular attention was given to the walls, kitchen, staircase and transitions between different areas.

This preparation helped the panels sit flat and supported a consistent finished floor level throughout the connected rooms.

4. Why a Low-Profile Dry System Was Selected

Traditional water-based underfloor heating is often embedded in a thick cement or liquid screed. While this construction is common in new buildings, it was not the preferred option for this renovation.

The height and weight of a conventional screed could have complicated the staircase, internal doors, kitchen fittings and adjoining floor levels. A wet installation would also have added a longer drying stage to the project.

Instead, a low-profile system with pre-formed pipe channels was selected. The panels incorporated aluminium heat-spreading surfaces that help transfer heat away from the pipe channels and across the floor.

For this project, the construction offered several practical benefits:

• Lower additional structural weight
• Reduced floor build-up
• No drying period for a thick heating screed
• Clearly defined pipe positioning
• Easier adaptation around fixed features
• Compatibility with the selected boarded floor construction

5. Installing the Panels and Pipework

With the subfloor prepared, low-profile heating panels were laid across the usable floor area.

The system followed the shape of the house rather than covering every part of the floor. Pipework was routed around the staircase, walls and permanent kitchen elements where heating coverage was not required.

The water pipes were installed inside the pre-formed channels. Curved return sections helped maintain controlled pipe bends and an organised circuit layout.

The aluminium surface increases the contact area around the pipe and helps distribute heat across a wider section of the floor. Pipe spacing, circuit length and water-flow requirements must be determined for each individual project.

6. Connecting the System to a Heat Pump

The hydronic floor heating system was connected to an air-to-water heat pump. In this project, the heat pump supplies space heating only; domestic hot water was not included.

An air-to-water heat pump transfers energy from the outdoor air to the water circulating through the heating system. Its actual efficiency depends on outdoor conditions, water temperature, building heat loss, controls and system design.

Radiant floor heating is commonly paired with heat pumps because it distributes heat across a large surface area. This can allow the rooms to be heated with a lower water temperature than would typically be required by smaller, high-temperature emitters.

However, no specific energy-saving or running-cost claims are made for this project. Actual results depend on the building and how the complete system is designed and operated.

7. Adding Load-Distribution Boards

Load-distribution boards were placed above selected areas of the heating system to create a stable base for the final floor.

The boards protect the system layers underneath and distribute loads across the floor. They were cut to fit around the walls, doorways, staircase and other fixed features.

The complete board construction must be compatible with both the heating system and the chosen floor covering.

8. Completing the Herringbone Floor

A wood-effect herringbone floor was selected for the renovated kitchen and living areas. Its pattern adds visual detail while retaining the warm appearance associated with a traditional timber interior.

Flooring installed over radiant heating must be approved for this application. Thermal resistance, underlay requirements and permitted surface temperature should be considered when selecting the final product.

Once completed, the continuous herringbone surface concealed the heating system and visually connected the kitchen, dining room and living area.

9. The Completed Renovation

Approximately 60–70 m² across the kitchen, dining and living areas are now served by the low-profile hydronic heating system. The panels and water circuits remain concealed beneath the finished floor.

The herringbone pattern creates a continuous visual connection across the open-plan rooms. It works with both the traditional features of the house and the updated kitchen, showing that a technical heating upgrade does not have to determine the interior design.

Actual temperatures, efficiency and running costs depend on the building, weather, controls and user settings. For this reason, no unverified performance figures are claimed.

10. What This Project Demonstrates

This project shows that water underfloor heating is not limited to new construction.

With a suitable floor design and heat-loss calculation, a low-profile system can provide a practical route for adding heat-pump-compatible heating to an existing home. Before installation, the project team should assess:

• Existing subfloor condition
• Available floor height
• Room-by-room heat requirements
• Heat-pump operating temperatures
• Pipe layout and hydraulic design
• Final flooring compatibility
• Door, staircase and room transitions

Frequently Asked Questions

1. Can underfloor heating be installed in an existing house?

Yes. Low-profile systems can be suitable for existing properties where floor height and structural weight must be carefully managed. The subfloor, heat loss and final floor covering should be assessed before system selection.

2. Does water underfloor heating work with an air-to-water heat pump?

Yes, when the complete system is correctly designed. Underfloor heating distributes heat across a large surface area and can operate at water temperatures suited to many heat-pump applications.

3. How much floor height does a retrofit system add?

There is no universal figure. The total build-up includes heating panels, pipework, distribution boards, underlay and final flooring. It must be checked against doors, stairs and adjoining floors.

4. Which floor coverings can be used?

Compatible options may include engineered wood, laminate, vinyl, tile and selected composite flooring. The chosen product must be approved by its manufacturer for use over underfloor heating.

5. Can the heat pump also provide domestic hot water?

Many air-to-water heat pumps can support both heating and domestic hot water when correctly configured. In this project, the heat pump was used for space heating only.