Retrofitting Hydronic Heating

2 October 2017
Room L Final copy

Underfloor hydronic heating is extremely popular, thanks to its ability to turn the home into one big, cosy radiator. Not only does it distribute an even, gentle and inviting warmth, but it’s also extremely energy efficient and allergy-friendly. It’s no wonder then, that plenty of homeowners are eager to integrate underfloor heating into their existing homes. While it is certainly more convenient to install in-slab hydronic heating in a new home, it is possible to retrofit an underfloor system into an existing home. 

When a professional installer assesses your home for its suitability for a retrofit, they’ll be checking where they can access the pipework. Depending on the configuration of your home, your installer may need to access under the house, or access pipework via the ceiling and walls.

If there is sufficient crawl space under your home, you may be able to install the polyethylene (or PEX) heating pipes to the floor’s underside, whereby parallel lines of tubing are stapled in between the floor’s joists, and then covered with aluminium plates, which act as an excellent thermal conductor. This method works with most existing flooring, but keep in mind that certain floor finishes have different levels of thermal conductivity. It’s best to consult with your licensed installer as to which floor coverings will be suitable for your new system.

However, when there isn’t sufficient crawl space, all floor coverings will need to be removed to uncover the joists from above. While this is a more involved process, it may still be worth pursuing when you consider the savings in energy costs you can make over the long-term. Because hydronic heating works at lower temperatures than conventional heating systems, it’s important to properly insulate the walls and floors of the home to ensure no heat escapes. Insulation battens are therefore fitted to the joists to minimise any downward heat loss. Heating pipes are then fitted on top of insulation boards and laid out in such a way to ensure there are no cold spots. Once the insulation boards are in place, a layer of screed is poured on top. The screed not only protects the pipes but also ensures the floors aren’t too hot to the touch.

In some cases, you may not need to rip up the existing flooring. Instead, your installer may choose to use a Minitec System from Uponor, which is a rigid panel with raised knuckles that allow for easy installation of the pipework. The Minitec panel is applied directly to the existing screed, timber or tiled flooring. Thanks to the raised knuckles, pipework can be slotted in easily, and the levelling compound that’s poured on top spreads evenly into all areas to create a strong adhesion. Due to the low profile of the panel, the floor level is only raised by approximately 15mm (before flooring is applied on top). And because the pipes are just below the flooring, the Minitec system delivers a quick heat up time. mini tec blog3Finally, a floor finish of your choice is applied on top. The best floor coverings for underfloor heating include ceramic and stone tiles, as they’re excellent conductors of heat. Some types of wooden floor finishes are suitable for floor coverings, but it’s best to check with your flooring manufacturer before proceeding with the installation. You might like to read our earlier blog post on selecting the right floor coverings for your new system here. With this method, the height of your doors and placement of skirtings may need to be adjusted to accommodate for the increased floor height. You might also consider adding a step between the adjoining rooms, as even just a few millimetres can make a noticeable difference. 


Installation and retrofitting of an underfloor heating system can be complex, and should not be a DIY job. Get in touch with the team at Hunt Heating today and find out how you can enjoy cosy underfloor heating in your new or existing home.