@wayne For hydronics talk to Gary Flood at the Enter Shop. They are in Melbourne but he has installers everywhere. http://www.enter-shop.com.au/ Alternatively Alex at AJs Plumbing http://www.ajsplumbing.com.au/ We generally do in-slab hydronics but have also done it inside a rammed earth wall (at our office so feel free to come and look) and underneath a timber floor (several times including in our office). Insulation is critical. In a slab make sure you insulate the slab edge as well as the underside. When we talk of hydronics we generally use heat pumps to create the hot water (it's free to run if powered by PV). You mentioned wetback stoves (wood powered heating). In my view timber is only a viable option in rural settings. In (sub)urban settings the particulate pollution is a serious health issue and there is a fair chance that at some stage woodstoves will not be permitted by urban Councils. You finished by talking of ducted air conditioning. Regardless of the technology used to generate the heat/coolth, ducted systems are inherently inefficient and, in my view, should be avoided at all costs. The heat pumps can be great but the principle of pushing heated air around requires pump energy (you have to move large volumes of air). Almost all residential installations have flexiduct (not rigid as in commercial offices), the ductwork (aside from a study showing 80% of them did not meet the Australian Standard insulation code) due to its flexi-nature has lots and lots of curves and bends all of which increase the need for pump energy. This is why is it not possible to get a rated systems as you can with a split system; it is totally dependant on installation quality. You also need to be mindful of condensation issues in ductwork as heated air passes through relatively cold roof spaces, again quality of ductwork can be a big factor here.

Hi Our company ‘Australian Sun Energy’ and ‘Warmboard Australia’ offers a full service for hydronic heating buyers including design, heat load requirements, heating systems and installation by our hydronic installers. There are many types of hydronic systems available, the 2 most common are in-slab and in-screed, in-slab heating the Pex piping is installed at the bottom of the concrete and attached to the reo mesh at 200mm centres, this system uses the concrete floor as a heat mass to retain heat for a longer period of time, pluses for this system are, once heated it only requires the boiler the add a small load to keep it at temperature, minus is that it takes a long time to heat up to temperature 5 days in some cases and can be an issues in Australia because we have such variable weather even in winter heating the house even on a warm days requiring the windows to be opened. In-screed the Pex piping is installed on top of the slab at 150mm centres then a screed of approximately 65mm is placed on top, this gives a faster heat up time but less mass to store the heat, minus is it’s more expensive to install due to 2 concrete pours. If your wanting polished concrete floors either of these systems will be suitable. Hydronic radiators and low to the floor wall systems heat the air space not the floor, as the heat rises from these units it heat the room from the top down meaning you can have a hot head but cold feet when it should be the other way round, pluses are usually a lower supply and install cost, minus are higher energy costs to run due to high water temperature and other factors. All gas boilers and heat pump heating systems specifically designed for hydronic heating are modulation systems meaning they adjust themselves down from peak load demand for example, 32kw to down to a low 3kw if this is all the heat required to keep the system at a stable heat. For more advice call Peter 1300 137 407

As Australias largest supplier of hydronic heating, we have been providing Australian homes with stylish, safe and comfortable hydronic heating and cooling solutions. As exclusive stockists of an extensive range of premium products, we ensure that all homes can enjoy the benefits of a low carbon, energy efficient system. We have just released an industry leading guide on Underfloor Heating, that contains information for both homeowners and installers, I believe the content within would be the perfect for many commenters on this post. If you're unsure on how to proceed with your project I recommend you take full advantage of our personalised consultation service, available for both homeowners and installers. Using the latest design software and coupled with the expertise of our Customer Service Team, you can rest easy knowing that we’ll design a bespoke solution that delivers superior comfort that is also environmentally friendly and energy efficient. If you would like a copy please email me on sophieo@huntheat.com.au, alternatively head to our blog to download a copy: Hunt Heating Blog

We are commencing a new build in Sydney. We are having polished concrete on the southern side which is a large open plan kitchen, dining and living room. Whilst we do have mild winters, being south facing, it won't get any sun in winter. We will have reverse cycle air conditioning, but are considering underfloor hydronic heating in this area. We will have solar also so would look to install using heat pump. I would love any advice and experiences on this. Thanks!