Heat Pump Heating and Cooling
Underfloor heating and cooling on suspended floors can be achieved with a heat pump. Therefore, consider underfloor heating and reverse cycle area cooling if you are building or renovating with suspended floors. If you choose radiator panels, then consider fan coil convectors for cooling in summer.
In reverse cycle, your heat pump will absorb heat into the cool water of the underfloor circuits and expel it outside. Fan coil convectors can absorb air moisture as well as heat using chilled water below the dew point. Consider convectors if you have a second storey because they are as effective for cooling as air conditioning.
Underfloor Heating
Underfloor heating is usually a bit more expensive than radiators. It depends on the nature of your installation and types of radiators selected. Mixing and matching underfloor heating and cooling with radiators may be a good option. For example, consider underfloor heating for your Kitchen and Living rooms and radiator panels for your bedrooms.
Also consider hydronic towel rails in bathrooms. This is more important if you don’t have underfloor heating. If you do, then electric element towel rails may suffice as a less costly solution for dying your towels in winter and summer.
Underfloor Cooling
For underfloor cooling, install a thermostat with a humidity sensor to ensure your floor stays above the dew point. A floor temperature of around 18 degrees in summer is about right. This will maintain your floor above the dew point. Also, 18 degrees is pleasant to walk on with bare feet and sufficient to effectively absorb heat and transfer that outside.
Underfloor cooling works best in dryer southern or inland Australian climates. For the most effective underfloor hydronic cooling, install ceiling fans to circulate air across the floor. Also, you will feel about 4 degrees cooler as soon as you turn the ceiling fan on.
Consider fan coil convectors if you have or are planning to install a radiator panel system. Convectors can also combine with underfloor cooling. They are designed for chilled water below the dew point. Therefore, they provide latent (moisture) cooling in addition to sensible (heat) cooling. More information
Floor Coverings
You can apply most types of floor coverings over your underfloor heating circuits although a decorative finishing screed or tiles are best.
Engineered timber boards are also quite acceptable. Most suppliers such as Havwoods will be happy to provide their normal flooring warranty over hydronic circuits.
Vinyl and open weave carpet can also be used if their thermal resistance is less than 0.15 m²K/W for effective heating and 0.09 m²K/W for effective cooling. Thermal resistance of floor coverings higher than this will make your underfloor heating and cooling system less responsive and less effective.
Consider combining underfloor heating and cooling in your Kitchen/Family Rooms over suspended floors with radiator panels or convectors in your bedrooms with carpets.
Consider also hydronic towel rails for your bathrooms if you don’t have underfloor heating there.
Installation Methods
Hydrosol recommends these two installation methods for underfloor heating and cooling on suspended floors:
- Minitec underfloor heating and cooling circuits, which will raise the floor level by 15mm minimum. Minitec is finished with a self levelling screed ready to take your finished flooring.
- Aluminium diffusion plates fixed between floor joists with insulation underneath raise your floor level by less than 1mm.
1. Minitec underfloor heating and cooling
Minitec can be laid directly onto your suspended timber or concrete floors. This thin capillary hydronic system will raise your floor by 15mm minimum. The pipes have a diameter of just 9.9mm with 1.1 mm wall thickness. They are laid close together with spacing of 100mm. Single flow and return pipe circuits can run up to 60m.
Feel the heat from Minitec in about 20 minutes.
For large floor areas, consider the larger version of Minitec designed for 16mm PEX pipe circuits. However, this will raise your floor by 30mm. This larger version of Minitec will allow your circuit spacing to be 200mm with single flow and return pipe circuits up to 100m long. Therefore, it will be less expensive.
Installation process:
- Glue the base board onto your floor to give a secure bond for floor finishes.
- Press the thin PEX-A pipes into the base board.
- Gather the flow and return pipe ends inside a cabinet or service room for connection to a manifold.
- Pour a self-levelling fluid screed over the circuits. The screed can have decorative additives if used as the finished floor.
- Otherwise, apply floor finishes over the screed once it has set, such as tiles or engineered hardwood boards.
2. Aluminium diffusion plates
Aluminium diffusion plates are fixed between floor joists with insulation batts underneath. This minimises heat loss underneath and directs the heat through the floor.
Aluminium is highly conductive. Therefore, they conduct heat quickly and evenly underneath the floor.
Lay structural flooring directly over the diffusion plates. Make sure there is contact between the plates and the flooring. Diffusion plates are designed for 16mm PEX pipe with floor joists set at 400 mm centres.
Installation process:
- Push insulation batts between the joists with a snug fit.
- Fit batons to the joists to hold diffusion plates firmly underneath the flooring for good connection and conductivity.
- Press PEX pipe circuits into the grooves of the diffusion plates.
- Gather the flow and return pipe ends inside a cabinet or service room for connection to a manifold.
- The structural flooring is laid over the diffusion plates and fixed to the floor joists.
Expanded polystyrene panels
A third method involves expanded polystyrene panels (EPS) such as Uponor Siccus FX.
Consider this method if you you need a lightweight solution over your suspended floor. Despite being lightweight, it has high compressive strength.
Expanded polystyrene panels are 25 to 30mm thick. Pre-formed grooves in the panels are designed to fit 16mm PEX circuits snugly underneath your finished floor surface. The aluminium face conducts heat from the hydronic circuits evenly through the floor surface. Lay cement sheets over the panels then apply your floor finishes. For greater thermal mass, increase the thickness of the cement sheets.
Expanded polystyrene panel
Installation process:
- Lay the expanded polystyrene panels onto your floor.
- Press the PEX pipe into the grooves of the panels.
- Gather the flow and return pipe ends inside a cabinet or service room for connection to a manifold.
- Lay thin cement sheets over the panels and PEX pipe.
- Mark the pipe location underneath.
- Fix the cement sheets to your suspended floor.
- Apply floor finishes onto the cement sheets.