15 November 2018
So you’re building your new dream home, and you love the idea of comfortable, radiant heat keeping you warm all winter? Here are 3 things you’ll need to consider before you start building.
1. What type of floor slab are you using?
If you’re building a new home, chances are you’re pouring a new concrete floor slab. But if you’re remodeling an existing property, you might already have a floor slab.
In a new slab, the easiest and most cost-effective method to install the pipework is to tie it to the steel reinforcing mesh. Once the mesh has been laid, we can install the pipework, ready for the concrete to be poured. In this case the hydronic pipework is installed within the structural slab.
Alternatively, you might pour an additional topping slab over your structural slab. This is common if there is an existing structural slab, or if your floor will have a polished concrete finish – the topping slab has different properties to the structural slab which makes it better for polishing.
In this case, we recommend the topping slab to be 90mm thick. There should be two layers of steel mesh – the bottom layer on 20mm chairs, with the hydronic pipework tied on top. Then a second layer of steel should be placed over the pipes which helps stop the concrete surface from cracking. The pipes are generally 16mm diameter, so this arrangement gives you 50mm concrete cover over your pipework.
As a final option you might look into a low-profile system such as Uponor Minitec which can be installed on top of an existing slab and is only 15mm-20mm thick. This type of system is more expensive however.
2. Which heat source will you use?
You’ll also need to consider which type of heat source you intend to use. In Australia, hydronic radiant floor heating systems are often heated by gas boilers which have the lowest installation cost. However, the price of gas is increasing so running costs are not as low as they once were.
As an alternative, electric heat pumps are becoming more popular, especially for properties without a connection to the gas network. These are more expensive to install than a gas boiler, (normally $5k – $10k more expensive) but are economical to run.
If you’re planning to install a solar energy system, the electricity you generate will help power the heat pump. So in that case it can be a cost-effective option as your running costs will be almost nothing.
Ultimately you’ll have to make a decision based on your budget, how long you intend to live in the property, whether you have gas or 3-phase power available, and your preference for renewable vs non-renewable energy options.
3. What size floor area are you heating?
In European homes, it’s common to install underfloor heating throughout the whole building.
However in Australia, many people prefer not to have heating in their bedrooms and opt to have underfloor heating in just their living room, or only in wet areas like bathrooms.
There are two types of underfloor heating systems – electric underfloor heating, and hydronic underfloor heating.
In short, electric systems are cheaper to install but more expensive to run. Hydronic systems are more expensive to install but cheaper to run.
The question is, which type of system makes more sense in the long term?
As a rule of thumb, if you’re only heating bathrooms then electric underfloor heating is probably better. The reason is that it’s a small area (usually only 2-3m2) and it’s not in use for long periods of time.
However, if you’re heating an open-plan living/dining room, often a hydronic system will be more cost-effective over time.
The smallest area you can reasonably install hydronic underfloor heating is around 40m2. Significantly smaller than this, and it’s probably going to be cheaper to just use an electric system.