My Rinnai
I saw frost for the first time in 2007 today. My wife has started to grumble about the cold. And the stores are full of heaters for sale, all of them claiming to be energy efficient. It’s time to review which heating options will warm your home without heating up the planet too much.
First, the worst: electric underfloor heating and open fireplaces. Talk to any underfloor heating salesperson, and they will tell you that underfloor heating is incredibly efficient. Talk to any homeowner who has had it installed, and they will tell you that their toes are very warm on the tiles (don’t these people own slippers?) and that their electricity bill shot up the day they turned on the underfloor heating.
The issue is not so much whether underfloor heating is efficient or not. It’s a form of central heating, and most South African suburban houses are not built for central heating. They have big, draughty, single-glazed windows, and uninsulated walls and ceilings. When I moved into my house, each room had a brick with big holes in it to let in outside air, for heaven’s sake. To centrally heat such a house with coal-derived electricity is an environmental abomination.
Open fireplaces have lots of charm, but two big drawbacks. The first is that most of their heat goes up the chimney, and in doing so, draws cold air into the house through any leaky door or window it can find. Nature abhors a vacuum. The second drawback is that, whether burning wood or coal, they emit lots of pollution up the chimney.
According to The Consumer’s Guide to Effective Environmental Choices, by Michael Brower and Warren Leon:
On a per-household basis, the most polluting option is wood heat. The main reason is the very high emissions of particulate matter from uncontrolled fireplaces and wood stoves. Particulates are given a heavy weight in our air pollution index because of strong evidence that they cause serious health problems.
I hate to diss wood heat, because it is carbon neutral, presuming that a new tree is growing in the place of the one you are burning. A good compromise is a modern, super-efficient wood stove, such as the ones sold by Franco-Belge or Morso. The best wood stoves produce one-twelfth the emissions of a typical fireplace.
Electric heat in all forms is relatively efficient, but that isn’t a great help because generating the electricity from coal is very inefficient, and releases far too much pollution and carbon dioxide. If you are heating a relatively small space for a couple of hours in the morning and few hours in the evening, however, it is an affordable, environmentally tolerable option.
Research at the University of Pretoria found that the quickest, most efficient electric heater for warming a space is a fan-assisted heater with a thermostat. Fin radiator heaters—often called oil heaters because of the liquid circulating inside them—and other heaters without fans are slower to heat a room and let much of that heat drift to the ceiling.
Radiant bar heaters, which glow red, do not heat a space, but can efficiently heat any person who stays close to them. If you are staying put, reading or working, they may be your best option, particularly if you buy one with a low wattage setting. (1000 W or less) Leaving one of these heaters on when no one is in the room, however, is a complete waste. An electric blanket is another good option for anyone who isn’t moving.
If you are lucky enough to live in a Johannesburg suburb with piped gas, this is an excellent option, particularly now that South Africa is importing natural gas from Mozambique. Gas is the cleanest-burning fossil fuel and releases the least carbon dioxide, too. Bottled propane gas also burns cleanly, but its global-warming credentials are tainted by the fact that in South Africa much of it is produced from coal. Gas is also more efficient than coal-derived electricity because the heat from burning the gas goes straight into your house, bypassing the inefficiencies of generating electricity.
Burning gas in an open fireplace takes us right back to where we started, however, with heat escaping out of the chimney. My favourite gas heaters are the pricey, but super efficient ones made by Rinnai. My Rinnai has given me three years of faultless service. I keep large, 48 kg bottles of LPG outside my house, piped to a wall outlet where I connect the Rinnai. It produces heat in seconds and uses very little gas. (To find a local dealer, phone the distributor Jay MacDonald and Sons, 021 696 7930.) The only problem is that my children fight over who gets to sit closest to it when they turn it on in the mornings.
I’ll take a risk and produce an unscientific ranking of heaters from best to worst:
1. Gas heater with piped natural gas
2. Gas heater with LPG
3. Modern, efficient stove burning wood
4. Modern, efficient stove burning anthracite
5. Electric bar heater for warming people who are staying in one place
6. Electric fan heater with thermostat
7. Other Electric heaters
8. Gas fireplace
9. Wood fireplace
10. Anthracite fireplace
11. Electric underfloor
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June 15th, 2007 at 11:57 am
You don’t mention solar heating here. What about a solar heater on the roof, heating water which would lead into radiators in the house (the kind of water radiators were used to have at school)? I have been searching for a supplier of such a system in South Africa, but with no success so far. Is it impractical?
July 18th, 2007 at 4:33 pm
It’s not impossible, but it isn’t simple. I have spoken to a few people with underfloor hot water heat linked to solar panels, and more significantly, I have experimented with it in my own house. The problem is that if you are working it off the same system that heats your domestic hot water, you are stealing heat from that system at the very time of year when you need it most.
A suitably sized solar geyser may not need any electrical help for 8 or 9 months of the year. But in the winter, when the sun is low and weak, almost all solar geysers need some help from electricity or gas to get the water hot enough. If you start extracting heat from the system to warm your house, you will only increase the amount of heat you have to add back into the system.
Systems that have been designed to significantly heat homes are oversized, with several solar panels and large water storage tanks. One I know has 4,000 litres of storage!
I do like your idea of radiators. My great uncle in Colorado heated his home using solar heat in hot water radiators. I think they might be more efficient than underfloor hot water and less expensive to install. But I’ve never seen a hot-water radiator in South Africa.
My list dealt only with conventional heating options. I know of someone in Cape Town who connected hot water to a wood-burning stove, which I think was used for underfloor in other rooms. I know someone else is using gas for hot water underfloor. Solar heated water supplemented by gas would be less polluting.
In colder parts of the world–including the Michigan, USA, house I grew up in–solar panels that blow hot air are the best-known option for solar heat, and I am amazed that they are non-existent in South Africa. (As far as I can tell.) The upside of forced-air panels is that they are much simpler and cheaper to build and install than anything involving liquids. The downside is that it won’t give you heat in the coldest part of the day. The most obvious solution is to insulate your house and allow it to overheat during the day. The more complicated and potentially more effective solution is to use a rock bin to store the heat.
One day I am going to experiment with some kind of forced-air solar panels for my home. In the meantime, I already have a modest variation on that theme. Reversed ceiling extractor fans blow warm air from my roof space into the house. I get a moderate amount of heat from these, but their downfall is that I have a very leaky roof and any wind cools my attic rapidly. I believe that modern roofs are commonly laid with a layer of plastic under the tiles; such a well-sealed attic would be ideal for this system. I based mine on that of a Pretoria engineering professor who heats his house EXCLUSIVELY with warm attic air.
Let me know if you come across a solution that works for you.
Don