Don’t Heat your Room with Tea Candles

November 19, 2014 by kris de decker Filed Under: Heating appliances, Random

hoax te candle heater

Friends and readers keep sending me links to a “low-tech” heating system in which tea candles heat a combination of ceramic flower pots. It seems you all need a course in thermodynamics, so let’s start with some basics:

1. First law of thermodynamics: you can’t create energy out of nothing, (and you can’t destroy it). This means that placing two ceramic pots on top of four candles does not increase heat production. You get the same amount of heat if you burn four candles without the pots.

2. Now imagine heating your room with four tea candles.

3. Get more tea candles. One tea candle can produce around 30 watts of heat, which means that you need at least 20 to 30 tea candles to heat a very small room (and replace them every 3 to 4 hours).

4. You have now built a small fireplace using tea candles. However, it isn’t running on wood but on petroleum — the stuff paraffin is usually made of. And above all,  you have built a fireplace without a chimney. Chimneyless fireplaces are very efficient, but they’re not so healthy and that’s exactly why the chimney was invented. Connecting your tea candle fireplace to a chimney will solve the indoor air pollution issue, but unfortunately 85-90% of the heat will then escape through the chimney. So you need more candles.

5. Forget tea candles, get some thermal underwear.

Chimneyless Houses

October 22, 2014 by kris de decker Filed Under: Fire, Heating appliances, Random

central hearth

“Early shelters were built of availale materials. Hides spread over poles or the bones and tusks of mammoths formed a type widely used. Stone and clay were common early building materials. Usually there was only a single room, with the fire located at the center of the living area. In many parts of the world this pattern changed little from the earlies times right up to the present. Smoke escaped from such dwellings as it could, through the low door or a smoke hole in the roof… The Scots developed a special word, snighe, for rain that worked its way through the roof sods and dripped down black with soot upon the people below.” [Read more…]

Crimean Ovens

March 4, 2014 by kris de decker Filed Under: Heating appliances, History, Random, War

“Starting in 1861, the wintertime Union field tent hospitals of the U.S. Civil War often used subterranean heating systems known as Crimean Ovens. The system under discussion was basically a firebox, or oven, on the outside of the tent, with a shallow, brick-lined, sheet-metal-covered trough running down the center of the tent’s interior, and ending in a chimney on the opposite exterior side of the tent. The tents were placed on ground with slight inclines, allowing the hot air to naturally rise and escape out the flue.”

crimean oven

“Dr. Charles Tripler, Surgeon and Medical Director of the Army of the Potomac, writes in a letter of November 1861 the following description of “a modification of the Crimean Oven”, devised and put into operation by Surgeon McRuer, the surgeon of General Sedgewick’s Eighth Brigade:

A trench 1 foot wide and 20 inches deep to be dug through the center and length of each tent, to be continued for 3 or 4 feet farther, terminating at one end in a covered oven fire-place and at the other in a chimney. By this arrangement the fire-place and chimney are both on the outside of the tent; the fire-place is made about 2 feet wide and arching; its area gradually lessening until it terminates in a throat at the commencement of the straight trench. This part is covered with brick or stone, laid in mortar or cement; the long trench to be covered with sheet-iron in the same manner. The opposite end to the fire-place terminates in a chimney 6 or 8 feet high; the front of the fire-place to be fitted with a tight movable sheet-iron cover, in which an opening is to be made, with a sliding cover to act as a blower.

crimean oven 2By this contrivance a perfect draught may be obtained, and use more cold air admitted within the furnace than just sufficient to consume the wood and generate the amount of heat required, which not only radiates from the exposed surface of the iron plates, but is conducted throughout the ground floor of the tent so as to keep it both warm and dry, making a board floor entirely unnecessary, thereby avoiding the dampness and filth, which unavoidably accumulates in such places.

All noise, smoke, and dust, attendant upon building the fires within the tent are avoided; there are no currents of cold air, and the heat is so equally diffused, that no difference can be perceived between the temperature of each end or side of the tent.”

Read more: 1 / 2 / 3.

Heat Your Desk, Not Your Office

November 13, 2013 by kris de decker Filed Under: Heating appliances

heated desk“Bloooms introduces a desk with a heated top, which is bound to enhance the comfort level of people who spend much time working behind a desk.

Research by the Dutch research institute TNO (Dutch Organization for Applied Scientific Research) shows that contact heating through the wrists is the most efficient way to warm the body — one can turn down the heater 1 to 4 degrees C°. If the undersides of the wrists are warm, the whole body will be warm. By working at a computer, for example, using the mouse, or writing, the wrists are placed on the work top.

The heating elements are integrated into the table top. This is possible, because Bloooms exclusively works with bamboo, which is eminently suitable to apply heating. It’s a stable material, that conserves its shape and properties when heated. A sensor triggers the heating the moment someone sits down at the desk, and turns it off when no one is sitting at the desk. The heating can be individually adjusted, and is therefore excellently suited to be used in spaces where there are several people at work.”

Bloooms heated desk. The company is working on a new version of their heated desk, which can be controlled by a laptop and will be ready in a few months. Related: Several readers have sent us a link to a prototype of a thermoelectric bracelet. It monitors air and skin temperature, and sends tailored pulses of hot or cold waveforms to the wrist to help maintain thermal comfort. Heat the individual, not the building.

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Rocket Stove Heating

October 11, 2013 by kris de decker Filed Under: Heating appliances

rocket stove in estonia

A rocket stove is not quite as efficient and clean-burning as a masonry heater, but it is much more DIY-friendly to build. The idea is that the configuration allows excess oxygen to increase the burn temperature of the fire. Hotter temperature means you want to store the heat energy into a high thermal mass material. Lots of great links at I fucking love rocket stoves.

Build a Solar Thermal Direct-Air Heater for $200

November 1, 2012 by kris de decker Filed Under: DIY, Heating appliances, Random, Solar

solar thermal direct air heater

“The town I live in is located near the Alberta-BC border, about 100 miles north of the US Canada border. Winters here are long and cold, but many days are crystal clear and sunny.”

“Our tool shed has a south-facing wall which was ideal to mount a solar thermal direct-air collector panel. The collector panel exterior dimensions are 48” high x 49.5” wide. Total budget: $200.00 Result: 16 sq ft harvest up to 6 kWh/day.”

Build a Solar-Thermal Direct-Air Heater (PDF). Introduction (and another project) here.