Hydronic Underfloor Heating System

Underfloor heating is a common method of heating homes throughout Europe and North America. It’s less common in Australia but is quickly becoming much more popular.

There are two types of underfloor heating available – electric and hydronic.

Electric underfloor heating consists of electric wires, usually installed under tiles. The wires heat up and warm the tiles. These types of systems are cost-effective to install, but expensive to run. They’re suitable for bathrooms and other small areas that aren’t in use for long periods of time.

Hydronic underfloor heating systems consist of a network of small pipes, usually embedded in a concrete floor slab. Hot water is run through the pipes, which heats up the concrete slab. Because of the extra materials involved, these systems are more expensive than electric underfloor heating systems to install, but they’re much more cost-effective to operate.


How are hydronic underfloor systems installed?

The most common (and cost-effective) method that’s used in Australia is the pipework is tied to the steel reinforcing mesh before the concrete floor slab is poured.

If your project has a “topping” slab then usually the hydronic pipework will be installed in the topping slab rather than the structural slab. This is to keep the pipes close to the top surface so the heat can radiate into the house. Topping slabs are common with polished concrete floors or if your property has an existing slab, and you’re constructing a new floor slab on top.

Generally, the pipework is installed in a ‘spiral’ pattern, spaced 200mm apart. This ensures even heat distribution throughout your house.

Floor Heating

Our engineers will design a suitable pipework layout based on your building plans, and we’ll coordinate with your builder to install the pipes once your steel is in place.


How do you heat the water?

The hydronic heating system isn’t connected to your domestic hot water system (used for your showers, basins etc.) Instead, the hydronic heating system is a separate, sealed circuit with its own heat source.

In Australia, the most common heat source is a gas boiler. These are cost-effective to install and run, and the boilers are compact in size.

Electric heat pumps are starting to become more popular, especially in areas not connected to a gas network. A heat pump is a similar mechanism to an air conditioner, except that it is designed to heat water rather than air.

Heat pump systems are more expensive to install than gas systems, but they can be cheaper to run especially if you’re also installing solar panels, which will produce free electricity to run the heat pump.

Alternatively, there are a range of other fuel types available.


Will the pipes leak?

Once the pipework is embedded in the concrete, it’s very low maintenance. The pipes are continuous lengths of plastic polymer pipe (usually around 100m long), so there are no joints or fittings within the concrete that can fail.

The only way for the pipes to leak is if they’re damaged during building. We pressurize the pipework with compressed air during construction to monitor its integrity, so we know if the pipes have been damaged by watching the pressure gauge.

Once your home is complete, there’s really no way for the pipework to fail. In fact, this is the least likely thing to go wrong with a hydronic heating system. There are many other components more likely to need maintenance, but fortunately these are all accessible for servicing. We recommend that you have your heating system serviced annually, before winter.


How is the system controlled?

We’ll install a thermostat that lets you adjust the temperature in your home. More complex systems might be divided into different zones, and each zone would have its own thermostat.

Hydronic underfloor heating systems work by heating the entire concrete floor slab of your home. Because this is a large mass, it typically takes around 24 hours to heat up from cold. For this reason, we always recommend that you turn on your underfloor heating system at the start of winter, and leave in on until the end of the season.

You can still turn the temperature down using the thermostat, so the boiler only runs when needed. This is the most efficient and cost-effective way to run the heating system.


What if I get a hot day during winter? Will my house overheat?

It’s pretty common to get an occasional warm day during winter when you won’t need your heating.

One great feature of underfloor heating systems is that they’re largely self-regulating. Because the surface temperature of the floor is only around 25°C, if the room warms up to the same temperature then the heat stops coming through the floor.

So even if you get the occasional warm day during winter, your house will still be a comfortable temperature and won’t be too hot.


What sort of floor coverings can I have?

Underfloor heating can be installed with any type of floor surface. It works best with heat-conducting surfaces like polished concrete or tiled floor.

However, it will still work with carpets – in this case we recommend using a thin carpet and either no underlay, or a minimal underlay.

You can also use timber flooring over your heated slab. In this case we recommend using engineered timber rather than natural timber. We also advise that the timber is fixed direct to the concrete – not mounted on battens with an air gap underneath. This allows the heat to transfer directly from the concrete into the timber.

We can provide advice on products and installation methods to use with your underfloor heating.


Will underfloor heat my whole house?

It’s a common misconception that underfloor heating only provides background heat, and that you’ll still need other heating to be comfortable.

In fact, if it’s properly designed and installed then an underfloor heating system can heat your whole house to a comfortable, even temperature, even in the coldest weather.

In many parts of the world, particularly in Europe, underfloor heating is the most common method for heating homes and commercial buildings. Australia is still catching up!


I have air conditioning. Do I still need underfloor heating?

Reverse-cycle air conditioning systems can provide both cooling and heating.

However, they’re always better at providing one rather than the other. In Australia, air-conditioning systems are almost always designed for cooling, and the heating function is really an ‘added bonus’ rather than a dedicated heating system.

The main problem is that the air diffusers are usually located at ceiling level. This is great in cooling mode because the cool air is heavier than warmer air, so when cold air blow

through the outlets into the room, it slowly sinks and distributes cool, fresh air evenly around the room.

In heating mode, the warm air coming from the air is lighter then the air in the room – so it stays at the ceiling! This means you’re heating the part of the room that’s above head height, and not that part where you’ll feel it. In many new homes with high ceilings, this problem becomes even worse.

Underfloor heating is much more effective because warm air rises – so warmth from the floor heats the part of the room that’s occupied.

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