Heating Upwards

Posted April 27, 2022


Imagine living in a warm toasty home with heating that you don’t see or hear. It’s just there, pleasantly warm. Damien McGill from the Healthy Home Cooperation tells us how.

In my last column, I talked about the importance of insulating your floor slab because you lose 10 to 35 per cent of your heat through the floor. What if we turned it all around and made your floor slab the heat source? Sure, we would have to add a bit more insulation, up to R3.0 in the South Island, but this is no problem for a company like MAXRaft, whose insulated slabs are often paired with in-slab heating systems. MAXRaft can provide insulated slabs in excess of R4.0, if required. That’s twice the legal minimum wall insulation!

In-slab heating systems are often the cheapest way to heat your whole home.

These insulated slabs provide the quietest, least invasive form of heating, with none of the draughts or blown air caused by heat pumps or ducted systems. There are no gas bottles to fill, no firewood to source, stack and chop. They just silently heat every room, as required, all winter long.

The most efficient in-slab heating systems are powered by air to water heat pumps, that extract heat from the ambient air to heat water that is then transferred around your slab in flexible pipes. Once your floor is up to temperature, the circulating water only warms cold spots, which is why in-slab heating is so efficient.

For the ultimate energy-efficient system, the heat pump could be connected to solar panels to generate the electricity needed to power it. If you’re on a budget, install the pipes now. They are cheap to install but tricky to add later!

In-slab systems can also provide summer cooling.

From a structural engineering point of view, the pipes should be fixed to the polystyrene, not the reinforcing mesh. The other benefit is that the slab doesn’t need to be any thicker than normal, saving money. If the heating pipes are fixed to the reinforcing, the slab must be at least 120 millimetres thick to ensure the pipes are buried, and the concrete doesn’t crack.

The main thing is to turn on your in-slab heating system towards the end of autumn, set it and forget it until late spring. Don’t touch, play or fiddle; just enjoy the quiet background warmth and the toasty toes!

027 348 1110 | healthyhome.kiwi 0800 006 029 | maxraft.co.nz

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