This week, my favourite little Rinnai gas heater stopped working when load shedding began on a cold night. It may use gas, but it also has an electric fan so it isn’t Eskom-proof. I’ve been looking at alternatives.
Last year at about this time, I wrote an overview of home heating options. In it, I ranked an open fireplace heated by gas 8th out of 11 options, well worse than average. This is because gas may burn cleanly, but any open fireplace loses most of its heat up the flue.
I failed to mention then that I own a Jetmaster open gas fireplace. In the past, I only used it a few times a year for ambience when we had guests, but I’ll have to use it a lot more during load shedding this winter since it’s my only heater that runs without electricity. That’s a problem, because LPG has risen in price from R367 for a 48 kg bottle when I installed the Jetmaster in 2001 to R820 now. And according to my own ranking, I’ll be using one of the least environmentally friendly options around.
When I first installed the Jetmaster, I briefly considered a wood stove, but I knew that wood burning was a source of carcinogenic particulates, and I didn’t see how wood made sense in a semi-arid country with so few trees.
I’ve learned two important things since then. First, I got a quick lesson in urban forestry a few years ago when I had to remove a giant dying oak from my garden. It broke my heart to see tons of potential firewood being carted away by a tree-feller who told me he was taking it to the dump. (The trunk and limbs were too large for me to split.) The logs would ultimately decompose, releasing greenhouse gasses without benefiting anyone. I called around and learned that some other tree-fellers cut and split the wood they retrieve to sell for firewood. In the future, I would only use a tree-feller who recycled this way.
Johannesburg is sometimes called the world’s largest urban forest. I suspect that this is hyperbole that could not be proven, but the fact is that the city creates enough firewood to heat many more local homes than it currently does. (Though not all of the homes, of course.)
The second education I received was when I began researching the latest wood stoves and fireplace inserts. They aren’t just better than open fireplaces, they are unrecognizably better. An open wood fireplace loses 90 percent or more of its heat up the chimney and releases about 50 grams of particulates per hour. Anyone who has read what I have writing about diesel emissions in the Mail & Guardian and on this website knows that particulates are a serious health risk.
But modern stoves typically emit 2 to 4 grams of particulates per hour, and some are closer to 1, that’s just 2% of the particulate pollution from a wood-burning open fireplace. And about a quarter of what a typical diesel car might produce. In addition, they retain 75 percent or more of the energy in the wood to heat the room, losing just a fraction to the flue. A free-standing stove unfortunately doesn’t suit my lounge, but the fireplace inserts are only a few percentage points less efficient and just as clean.
Perhaps most important, burning wood is widely considered to be almost carbon neutral, because a decaying dead tree would release carbon dioxide anyway, while a new tree growing in the place of the old one absorbs the greenhouse gas. Firewood from the urban forest is even closer to carbon neutral than most because it was going to be cut anyway and involves minimal transport.
Only two fireplace inserts fit my opening, but they seem like good units. I’m seriously considering the Scan DSA 3-5, which rates at 76 percent efficiency. I haven’t yet found particulate emissions data for this fireplace, but it seems similar to the DSA 4 which emits a very low 1.1 grams of particulates per hour. If I could choose among a wider range of wood stoves, I would look for one with the Swan eco-label. Among the brands in South Africa, Scan, Morsø, and Jötul all have stoves that meet the wide variety of environment criteria to earn the Swan logo. A list of Swan stoves can be found here.
These advanced, closed-combustion stoves are not cheap. Expect to pay at least R10 000, and up to R40 000 for a top-of-the-line wood burning stove. But the wood is cheap. Malcolm Sims of Cosy Heating has done calculations suggesting that gas now sells for R1.23 per kilowatt hour of energy, whereas wood is about 30 cents per kwh if burned in a 75 percent efficient stove-cheaper than electricity. (Cosy Heating sells both gas and wood heaters.) Comparing my inefficient Jetmaster with the Scan fireplace, I could heat with wood for one-tenth the price, though the Jetmaster offers greater control in adjusting the flame, which would mitigate that somewhat.
Sadly, Cosy Heating says that my Scan fireplace is out of stock because of the load-shedding rush. So for the next seven weeks we’ll be huddling next to the open gas fireplace when the lights go out, and thinking about how warm that chimney must be.
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April 29th, 2008 at 3:16 pm
There is nothing much new under the sun when it comes to stoves. Benjamin Franklin of US fame invented the Franklin Stove when New England’s forests seemed to be in danger. You should be able to obtain the plans from the Web and get one made locally a lot more cheaply.
May 7th, 2008 at 10:32 am
I would have to disagree, much as I like Ben Franklin. Any closed wood stove is more efficient than an open fireplace, but there is a big difference between an old-fashioned wood stove and modern wood stoves. According to http://www.woodheat.org:
Smoke (particulate) emissions from older conventional wood stoves average at least 25 grams per hour of operation . . . In contrast the EPA regulation limits emissions of certified wood stoves to no more than 7.5 g/h. However, since the regulation was first established in 1988, the average emissions of certified stoves has declined steadily due to advances in technology and competition among manufacturers. Today, most current wood stove models emit only 2 to 4 g/h.
For example, much of the energy in wood is released in the form of gases, which normally go up the flue unburned as pollution. The modern stoves inject hot air at the top of the box, which causes the gases to combust. Ben Franklin missed that one.
Sadly, there are no South African-made stoves that incorporate these technologies. (I would be happy to be proven wrong on this one.)
If you live in a rural area where air pollution is not an issue and have an ample supply of wood, any old stove is fine. In the cities and suburbs, however, we owe it to our neighbours to use the latest clean technology.
May 8th, 2008 at 4:39 pm
Before someone writes to correct me, let me correct myself. Jetmaster has recently begun manufacturing locally-made stove that use the same technologies employed by the European stove companies. They have not been as rigorously tested for emissions as the imports, but after a long conversation with the head of R&D at Jetmaster, I am convinced that they are roughly in the same league. They are also much less expensive. One reason is that they are made from mild steel instead of cast iron. Jetmaster is convinced that they will last just as long, but since these are new products, it’s hard to be sure. Another company, Heatwave, also manufactures a closed-combustion stove in South Africa, under the brand name Bogen. I know nothing about this product at present.