There is a rumor going about that you can heat a tent with a candle..
I have experienced bitter cold at 4 o'clock in my tent and it would be perfect if I could heat it enough for winter camping.
- Wood stove, rocket or classic stove needs a new log every 15-25 mins and if you are alone (as I am) you won't get much sleep
- Greenhouse petrol heater can burn all night but you have to carry the stinky fuel with you, hoping not to spill it in your backpack. Also maintaining wicks and glass is not a pleasure. On the plus side you have light all night. On the downside - no chimney.
- So wax it is. As a fuel - it is almost perfect. Easy to transport.
Here is some data about wax:
According to Wikipedia and my own test, (see the file "Energija voska"), a tea candle can produce avg. 30 W/h.
On several sites you can find articles which explicitly state that one candle is not enough to raise the temperature in a tent - heat losses through fabric are too extreme.
What if I take more candles (e.g. 10 -15) i,e, 300-450 Wats ?
If I add a chimney, would that eliminate the CO/CO2 problems?
D: http://www.ncbi.nlm.nih.gov/pubmed/15138958 Carbon monoxide poisoning while using a small cooking stove in a tent.
Leigh-Smith . Carbon monoxide poisoning in tents--a review. Wilderness and Environmental Medicine. 2004 Fall;15(3):157-63. and other sources
A tea light candle can burn 8 hours,.. Is it safe to go a sleep near burning candles?
Let's try and find it out....
First, I tested a possible chimney. It has to be cool enough at the top to go through a hole in the tent fabric with a temp as high as 40-50 Celsius. I took a can, cut out door for tea-light and made a 20 mm diameter chimney from metal broomstick handle. Light a candle and measured the temp on tube 120 cm above the can. The can top reached a temp of 80C and the tube/chimney at 120 cm had 40 C.
Step 1: Assembling the Stove
I decide to made a stove for 16pc 35mm diameter tea light.
In the store I found a metal bread baskets which is the perfect dimension for the candles. Why baskets? It will serve as protection from direct contact heat transfer from the stove surface (up to 160 C) with the tent, sleeping bag, blankets, fabric etc.
For the stove I took a big can from the scrap yard, and cut out a metal sheet 0,35mm thickness. Bent it into two equal boxes - bottom and top. Inserted a tube (chimney tube adapter).
The idea was to have a central chimney which can eventually serve as the central tent pole in my (KP teepee) (Tipi tent) - later I abandoned this idea.
Step 2: Assembling the Stove... Continued
Idea was to fasten it to the central pole. The stove lower box is fixated 8 cm above the floor and the upper box can slide up and down to load the candles (or extinguish flames).
Chimney tube has 6x8mm holes serving as candle smoke intake inside the boxes.
Testing time ...
I filled it with candles, lighted them and watched. Everything was perfect, the top box reached temps of 240C and the chimney at 120cm measured 55 C. The outside temp was 15C - no wind. Test run time was 3.5 hours.
Candles went out unevenly - in the last hour only 6 flames were burning. All the other wicks drowned in melted wax.
There was too much heat inside the box for wax (i.e. over 75C), which liquified in the bottom of candle pot.
OK. Let's go further
Step 3: Testing the Final Design
Satisfied with previous test run, I finalized the stove.
The chimney was shortened, and only attached to the top box. Now the exhaust is 20 mm in diameter. I should get a better draw because of this.
I mounted 4 wooden legs on each side of the lower basket and built a door for sliding a small plate (drawer) of candles made out of perforated metal sheet. The chimney was attached to my hiking pole which serves also as central tent pole.
Looks very nice....
Fully loaded the test started perfectly.
For 2 hours I left it unattended. And suddenly smoke - the wax start burning!
The flame was very difficult to extinguish - what happened?!?!
As a fireman after a disaster, I collected facts:
- Temperature in a box was so high that IR rays reflected down and ignited the wooden leg which started an open fire under the candles! You can see the result in the pictures. Imagine that in the tent ... back to the beginning !
- No more wood near/on stove
As shown on the last picture, I inserted 4 long 16 cm screws, divided with nuts, through the box which serve as legs making the distance from the ground 8 cm. They also connect two halves of the stove together...
More to come...