Fuzzy Warm

For a perfectly comfortable living space, we've installed underfloor heating & cooling. Our climate is fairly mild. It gets hot (30+deg C) and cold (5deg C), which is fairly temperate compared to Virginia for example, where you can add another 20deg to the temperature swing. A comfortable temperature for the whole year then is around 21 degrees, cool in the summer and warm in the winter. And that's where the underfloor heating & cooling comes in. This highly technical system that normally requires the input of engineers, architects and consultants actually only required a tiny bit of planning, a few coloured wax crayons and a sheet of polystyrene. And of course a few other pieces of polystyrene, pipes and connectors...

So the A-Z of our heating and cooling system is as follows (and donations are welcome): We insulated the floor of the house from the ground by laying 100mm layer of polystyrene down on the floor which had first been compacted, treated for termites and leveled with river sand. The polystyrene is what they put in into the floors of large fridges and freezers. Onto this we then laid our coils of piping which transfer the heat into or out of the slab. To ensure the heat is delivered to the correct room, we installed the delivery piping in the middle of the polystyrene effectively insulating it from the slab and the ground. When it reaches the relevant room, it is brought out of the polystyrene and that section is then cast between the polystyrene and the slab. The heat is then transmitted into or out of the slab.

Each room or zone has its own supply and all the zones share a couple of return pipes. The diameters of the supply and return pipes obviously differ, but it significantly reduces the amount of piping required.



Just to be different, heating is also provided in all of the cupboards. The theory behind this is to keep the cupboards permanently warm with ventilated air to prevent any mould build up. It's a problem here and I'm tired of mould growing everywhere while I sleep. These circuits are supplied separately to the rest of the circuits in the house.

The supply manifold is simplicity itself. There are no fancy solenoid valves with separate temperature controllers - another costly item to maintain or repair. We just have a simple system to regulate flow rate which when 'tuned' should provide just the right amount of heating and cooling to all the rooms in the house. This may take a bit of time to achieve, but it is not rocket science. And the picture is pre-manifold installation.

Currently we are busy with installing all the pipework, geysers, pumps and controllers in the 'control room'. The pumps are beautiful little things that can be set to different operating powers: 30, 60 or 90W. This is quite handy when you have different flow requirements and they are the same pumps that were supplied with the solar hot water panels.

Just to boost the heating in winter, I have ordered a slow combustion fireplace with a boiler attached. This will be connected into the system and the beauty of this is that we will be able to distribute the heat from the fireplace throughout the house. It supplements the solar heating, which is what we will be using to heat the water that will heat the house.

The benefit of the insulated floor extends to the hot water supply for all the bathrooms and kitchen. We have installed a ring supply which is also buried and insulated in the polystyrene. This allows us to circulate the hot water from time to time which has a significant water saving consequence. When you open a hot tap, the hot water will almost instantly arrive at the tap. This saves leaving the hot tap running while you wait for the water to arrive and in some houses that I've lived in, this can take ages and consume gallons of water. Being insulated in the polystyrene obviously saves significant amounts of heating energy. This means that the circulating pump need only operate for a minute or two every hour.

To cool the house, all we do is pump cool water through the pipe network. This should cool the floor down to around 15 degrees C which should make everything feel quite comfortable. The cool water is provided by a geothermal loop that has been buried outside - all 600m of it. Again this is free energy except for the circulating pump which uses next to no power even at full output. Nevertheless, considering the design of the house I expect that the heating and cooling needs will be minimal even at the worst of times.

So the only question that now remains is how well does all of this work? And that answer needs a bit of time and experience. But it will work.