Heat pump hydronics in Australia is possible but face a few challenges:
- It’s an expensive solution – unlike in Europe the systems and installation tend to be priced at a premium as a “luxury” system. Installing a system during a renovation may cost approx. $30k.
- It can be hard to find a good, knowledgeable company which wants to install heat pump hydronics. Most hydronic companies in Australia just want to install gas boilers, which is what they’re familiar with.
- Efficiency is lower than good standard air-air heat pumps, i.e. reverse cycle air conditioners.
Converting from gas-powered to electric/solar powered hydronics can be tricky, because the water is heated to a different temperature, so all the radiators may need to be changed. There are also other considerations, such as whether the water running through the system contains anti-freeze, anti-rust, etc.
Underfloor hydronics may require insulation under the concrete slab, as well as on the sides of the slab, as heat can radiate down and out of the sides. There is a lag to the space being warmed, while the slab itself heats up.
In terms of using solar for hydronic heating, climate can come into it as well - if you are mainly heating during a cold, dark night, solar can't help you! That said, if it's a well-insulated home, you can potentially warm it during the afternoon and have the heating turned off after sunset. Some places, like Canberra, might be better suited to this - with their cold, clear days and higher solar radiation.
The main advantage of hydronics is the “quality” of the heat as it’s radiant. But a similar result can be obtained in other ways, e.g. building or renovating to a PassivHaus standard.