Hydronic underfloor heating is a popular form of home heating in Europe and North America, where it’s normally just called “Central Heating.” In recent years it’s become more common in Australia, particularly in Melbourne but also in Adelaide and Sydney.
Hydronic underfloor heating is different to electric underfloor heating. The word “hydronic” just means that we’re using water to move the heat around.
An electric underfloor heating system consists of wires installed beneath the surface of the floor. Either they are installed under tiles or embedded in a concrete slab. When electricity is run through the wires, they warm up, like an electric stove element.
Electric underfloor heating systems are cost-effective to install, but expensive to run, because they use a lot of electricity. They’re suitable for bathrooms and other small areas that aren’t used continually, but not as common for living rooms or other large areas that are occupied for long periods.
Hydronic underfloor heating systems create the same effect, but instead of wires they have small pipes installed in the floor. The most common method to install the pipes is to lay them in place before your concrete floor slab is poured, so that the pipes are embedded within the concrete.
Hot water is then run through the pipes, which heats up the whole concrete slab. These types of systems cost more to install than electric underfloor heating, because of the extra materials and work involved. However, they’re much cheaper to operate which means you can use them to heat your whole house.
How is hydronic underfloor heating installed?
Here in Australia, the most common method is to tie the pipework to your steel mesh before your concrete floor slab is poured.
Sometimes a home might have a “topping” slab – a second layer of concrete on top of the structural slab. This is often the case for polished concrete floors, where a different type of concrete is used for the polished layer than for the structural layer. It also might happen if you’re renovating your home and have an existing slab, but your builder is pouring a new concrete layer on top.
In this case, the hydronic pipework will normally be installed in the topping slab instead of the structural slab. This makes sure that the pipes are close to the floor surface which allows the system to start heating your house faster.
Usually, underfloor heating pipework is laid in a ‘reverse-spiral’ pattern, which helps distribute heat more evenly into the room. Most commonly the pipes are spaced around 200mm apart, although in areas which need more heat sometimes they can be closer together.
Will my house overheat if there’s a hot day during winter?
In Australia it’s common to get a warm day during winter where you might not need the heating system turned on. This isn’t really an issue for underfloor heating systems, because they operate at a low temperature – usually the floor surface is kept at about 25°C. If the temperature in the room get up to the same temperature, the heat stops coming through the floor.
In this way, underfloor heating systems are self-regulating and don’t usually overheat.
Can I still have carpet with an underfloor heating system?
While underfloor heating systems work best with floor surfaces that conduct heat, like tiles or polished concrete, they still work with other floor coverings as well.
If you’re putting down carpet, then it’s best to use no underlay. A thin layer of carpet lets the heat through better than a thick layer.
Timber floors are also an option, but you should check with your supplier about whether the heated floor will affect the wood. Generally, natural timbers aren’t suitable – the heat can cause the timber to dry out, which make it warp or bend. Most engineered timber floors are suitable for used with underfloor heating.
Any timber floor should be installed floating – with a foam underlay (generally around 3mm thick) and not mounted on battens. The air gap created by the battens stops the heat transferring from the concrete into the timber.
If I have underfloor heating, do I still need additional heaters?
A hydronic underfloor heating system is designed to heat your whole house, without the need for other heating. Even in the coldest weather, you’ll be able to get enough heat from the underfloor heating alone.
In Europe and many other parts of the world with cold climates, hydronic underfloor heating is the dominant method for heating buildings, even commercial premises.
My house has air conditioning, so do I need underfloor heating?
Reverse-cycle air conditioning are generally designed for cooling rather than heating. This is because their main benefit is that they remove moisture from the air, which reduces humidity. This makes a big difference in hot weather.
You’ll notice that air conditioning systems usually have the air outlets on or near the ceiling. This is because cold air is heavier than warm air – so cool air from your AC system will sink, and fill the room on a hot day. However in heating mode, the warm air from the AC system tends to stay near the ceiling, which doesn’t help heating the people in the room.
Underfloor heating is more effective, because warm air rises. So it mostly heats the part of the room closest to the floor, which is where the people are.
Article Credit: Luxury Heating & Cooling