Heat Your Room with 1 Candle plus Flowerpots, Nuts and Washers

Tactical Intelligence
Wednesday, 20th November 2013

If you want to heat a room with just one candle and save even more money you need to create thermal mass and then radiate it with terracotta pots. It more simple than you could ever imagine.

After a crazy week when half a million people visited our site to check out the video, 'How to Heat Your Room for 8 Pence a Day', we thought you would appreciate a refinement of this idea that generates even more heat from a candle by increasing the thermal mass within the first pot. Please share this page too so that those who saw the first post can also test out this new design.

Putting it all Together

The process for putting together the candle heater is very simple:

What You Need

Some stainless steel nuts, washers and a bolt plus three flowerpots! Do not use zinc as it gives off toxic fumes when heated. Here's the detail.

  • One 4? terracotta (not glazed) pot

  • One 2? terracotta (not glazed) pot

  • One 1 1/2? terracotta (not glazed) pot

  • Two 1 1/2? x 1/4? washers

  • Three 1 1/4? x 1/4? washers

  • Three 1? x 1/4? washers

  • Eight 3/4? x 1/4? washers

  • Seven 1/4? nuts

  • One 3? x 1/4? bolt

Assembly Instructions

I think that the easiest way for you to learn how to put one of these heaters together is to follow the cutout image (to the left) I used from the heatstick.com site:

Making the stand

I found the simplest stand to make is to purchase three 4? corner braces.

















Then just put the three braces together with the middle brace facing the opposite direction and bend the outside two just enough to support the heater.

How it Works 

The basic purpose of this heater is to capture the heat given from a candle flame and to concentrate it into a steel and ceramic radiator assembly. After some time, the ceramic surface will act as a thermal mass and begin to radiate the captured thermal energy into your room or office. Here's how heatstick.com describes it (image and description c/o heatstick.com):

Heat rising from a burning candle (or electric lamp) is first trapped in the Steel Inner Core and surrounding Ceramic (Terracotta) Inner Module.

The Inner Cores get very hot and radiate heat to the Ceramic Middle Core.

This entire inner region gets VERY VERY HOT! Heat synergistically builds up and 'boils out' of the Terracotta Inner Core into the Ceramic Middle Core. The Middle Core heats up and begins to Radiate Heat. Heated air 'boils out' into the Terracotta Outer Core.

The Large Surface Area of the Outer Core begins receiving Heat. The inner wall surfaces become very HOT! Heat travels through the wall to the Outer Surface.

The Outer Surface gets VERY WARM to HOT and gently begins to Radiate Heat into your home or office. 

Cross-posted from: www.tacticalintelligence.net/blog/how-to-make-a-candle-heater.htm


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Old salty |
Wed, 20/11/2013 - 16:38

Just saying ... Back when I was going to school one of the Physics courses I took made it pretty clear that you can't create energy. The BTU Value of the candle is a given and it can't some how become warmer by having a mass of clay pots and washers suspended above the flame.. In fact the heat normally given off by the burning wax is firstly consumed by the suspended mass there by reducing the normally felt heat until the mass has heated to the point it radiates for the occupants to feel... make a real test to prove your point. . measure degree hours in a confined space with equal candles.. on plain one with your Mass suspension idea. red temp ever so minutes and make a graph.. you will see.. BTU value of the fuel is equal. NO Magic.

Kobutsu Malone |
Wed, 20/11/2013 - 17:40

This article is highly misleading to those without a scientific background. The bottom line is that you can't create any more heat from a candle than what is there already... if you are storing the heat in a "thermal mass" or storing the heat in the mass of the air of the room... there can be no net gain unless more energy is introduced into the system. Constructing the above contraption is a complete waste of time, you can't get around the laws of thermodynamics with a few flower pots! As Old Salty says.... NO Magic!

clv101 |
Wed, 20/11/2013 - 17:58

I'm a big fan of Permaculture Magazine, but this article falls well below your usual standard. It's bad advice.

Firstly, energy is energy is energy. Burning 1kg of candle wax releases around 13 kWh of energy. This much electricity costs around £2. Are the candles you're burning less than £2/kg? Unless they are then this is more expensive than heating with electricity (and much more expensive than heating with gas).

Secondly, if you are using super cheap candles they are they are likely to be made from imported palm oil, grown at the expense of rain forests and orangutans.

Finally there are indoor air quality issues and the increased fire risk of having candles burning routinely. Seriously folks, this is a bad idea and not one I'd expect Permaculture Magazine to promote!

Friendly add vice |
Wed, 20/11/2013 - 20:43

A good homemade thermal mass might be part plaster of paris and part sand. moldeable with artistic potential.

Thermal mass is much more efficient for heating homes than the "thermal mass of air" as one of them said. In Denmark you can't build a new home unless it uses thermal mass for heating. heating air is very innefficient and uncomfortably fluctuating. The idea of thermal mass was pioneered by the people's of Siberia. They'd live through arctic winters in uninsulated cabins using very little wood. More info can be gleaned by researching "russian stoves" and "masonry heaters" as well as "trombe walls" and obviously the "concrete slab and rocket stoves". Anyone know russian? Go over there and write a book about the thermal mass stoves in English, there are still a few people working on this. Not much info on this stuff within the collective consciousness, as evidenced by the above misinformed comments.

Robbbi |
Thu, 21/11/2013 - 01:13

Commenters who say: "a candle can't heat a room" AND "heating air is inefficient" are Both correct! If you ever ate on a chilly patio but felt warm from a radiant heater, that's what this little guy does: it heats the people close by who are line of sight. You could analogize: fireplace in a flowerpot. I too do not want to burn candles indoors, so I will pass on this...

Maddy Harland |
Thu, 21/11/2013 - 11:21

I posted this online because thermal mass does actually increase temperature retention in the room. If you have a fireplace and you burn wood, you get a certain amount of heat and the rest goes up the chimney. If you have a candle alone the same is true - heat rises and much of it is lost. If you have a wood burning stove that sits in a good quality cast iron box the heat from the combusted timber not only heats the air, it heats the cast iron and that retains heat longer than the air (thermal mass) and radiates it better than a naked flame. The same is for this device of 3 terracotta post and the stainless core - the candle heats them. They create a small but effective thermal mass that radiates out. The above comments claiming science are indeed lacking in an understanding in thermal mass design. The best way is to try it out. I agree however that paraffin tea lights from Ikea are not the way forward. Please post a link to the source that says they are made from palm oil in Borneo. If that is so that is essential information everyone should know.

Frances Hunt |
Thu, 21/11/2013 - 12:46

Science needs to interact with humans to be of practical application, so everyone above is right in some manner. The gadget changes the candle flame from radiant heat (mostly) to convective heat (mostly), it produces no additional energy, but does act as a storage pot & so amplifies its output -after a bit of a wait, and maybe a lot of candles.

I like the point heat source of my woodburner (modern type with max convected heat) much more than an infra-red heater that heats surfaces like skin but not the air in between, unless it is convected back - tho it's a very efficient source as electric heaters go. I also prefer the stove to my conventional convector rads which i only use in extremis because the radiant flame has its effect too. Nothing nicer than standing with back to fire after coming in from the cold.

So if you can get hold of cheap sustainable ethical candles, you wont save energy & risk setting light to your house, but it changes the flame into human comfort & gratification.

Better tho is insulate insulate insulate, ventilate controllably, get a govmt that doesnt think green measures are crap, and maybe stay in bed until then!

Debbie |
Thu, 21/11/2013 - 13:30

I posted on the other article but want to repeat what I put there on this one too and add a little more.

I used this method for a small (6 x 8) glass greenhouse last winter to keep the chill off seedlings and overwintering plants - I no longer wanted to use paraffin heating because of the costs and having it hanging around. I used single church style candles (one at a time) which I made myself from recycled wax. Yes it was hydrocarbon based wax not soya or beeswax.

The greenhouse was fully insulated with heavy duty agricultural bubble wrap and the plants covered with a layer of horticultural fleece every evening.

It worked really well for the plants and seedlings - indeed they seemed more robust than in previous years.

As I've said elsewhere - I would not want this set-up in my home as prodigious amounts of oily soot were generated which covered everything. As the plants were covered at night - they were OK. Also we had to use oven gloves to remove the plant pots to blow out the candles - they got extremely hot - a possible hazard for pets or children in the home?

Neither would I have wanted to spend an evening in there - for a small space it didn't exactly get subtropical - can it really heat a bigger room that effectively?

miltonics |
Thu, 21/11/2013 - 16:38

I think it should be realized that this is one technique for the toolkit, among many others. It's probably not appropriate in many (or most) situations, but there remain a few where it can either be used directly or the principles adapted.

If you did not have heat you would be very happy to have this rather than nothing.

Maddy Harland |
Thu, 21/11/2013 - 19:15

I consider myself very lucky to have an efficient woodburning stove. When the power goes down I can cook on it and I have candles (beeswax!) and a least one LED rechargeable lamp. But for people who don't have a stove, this is a useful temporary solution to a power cut. It is also useful for people on electricity metres who might run out of money at the end of a month and rely on their electricity for heat, especially if you can make this device out of recycled parts. That's the point of this post - not to advocate its use as a great idea for life. It is a temporary solution. It also has to be utilised with all the usual health and safety common sense like don't touch hot mental or terracotta and leave the device unattended. Put it on a flame proof surface as well please.

grrwaa |
Thu, 21/11/2013 - 20:09

I have read everyones comments on this heater, I made a similar one myself the other week and use it with three tea lights. It's perfect for defrosting my old land rover on a cold morning before I go to work with them being made from mainly aluminium and having notoriously poor heaters.
One hours worth of burning means a toasty motor (no more scraping ice off both sides of the windscreen). Far more cost effective and environmentally friendly than running the motor for 20-30 minutes and scraping away like a mad man
I see why people are objecting to the 'flower pot heater' but everything has its use/place, use your nonce and everything will be hunky-dory.

Joe Pacal |
Fri, 22/11/2013 - 23:47

This thing will do extremely little or in most cases nothing to improve the heating performance of a candle. Thermal mass is useful for storing heat when it is warmed and releasing heat when the surrounding air cools. This is not a relevant application here and these little flower pots are an insignificant amount of thermal mass anyway. The surface area of the flower pots will transfer heat to the air when heated by the candle but the candle is already transferring all of its heat to the air without them. You can feel a very hot and narrow column of air rising a few inches above the flame. Within 2 or 3 feet above the flame, most of this heated air is dispersed by air currents in the room. The flower pots will disperse the heat closer to the flame but there is not any advantage to that in most cases, and a much simpler device such as a beer can with a few holes punched in it would work just as well. In situations when you need some extra heat you could take whatever science books you might own and burn them since you obviously aren't reading them. You muck up the reputation of Permaculture when you publish carelessly tested ideas and you violate one of Permaculture's main tenants; you are not being a careful observer of Nature if you think that your flower pot contraption is providing any advantage.

Furthermore, your use of the term "boils out" is wrong. Boiling is a rapid phase change from a liquid to a gas that actually absorbs energy in the same manner that evaporation produces a cooling effect. When you say that the "inner region gets VERY VERY HOT!" you are experiencing high temperature but very little actual heat, due to very small amount thermal mass and very small source of heat. (A piezoelectric ignition spark produces an extremely high temperature, and an extremely tiny amount of heat.)

Scomber |
Sat, 23/11/2013 - 20:47

Paraffin candle wax is, of course, a refined fossil fuel. It generally costs upward of $3 per pound here in the USA. It has 18,000 BTU per pound. Assuming 80% combustion efficiency, that means you get 4800 BTU per dollar.

On the other hand, the traditional Japanese under-the-table hibachi room heater burns charcoal. (Yeah, be concerned about air quality with either fuel.) Charcoal has 9700 BTU per pound but the high quality, real wood "Cowboy Charcoal" brand goes for $16 per 20 pound bag, or 80 cents a pound. At similar efficiencies, that gives 9700 BTU per dollar, and it's not a fossil fuel.

I hear our power bills are going up next year, and we'll be paying 19 cents per kWh for electricity. Resistance electric heat (the most economically inefficient way to heat around here) would then give you 3412 BTU per kWh, or almost 18,000 BTU per dollar. Results of this very depending on your electricity cost.

Any other conventional fuel is cheaper (more BTU per cost) than resistance electricity.


Stamish |
Sun, 24/11/2013 - 02:50

I have to agree that everyone's comments are right!
I like how the Flower Pots absorb the Candle's Heat! It seems to me the Flower Pots will slow down the transfer of Heat while the Flower Pots are hot!
I have an idea that I will be working on tomorrow because when anyone tells me, "This or that wont work" I have to try!
I will let you know how my project works out!
I will not be using candles!

Joe Pacal |
Sun, 24/11/2013 - 06:26

As I understand it, the Japanese under-the-table heater is NOT a "room heater"; it is intended to warm the area under and around a table where people are sitting. This takes less energy than heating the entire room. If you want to reduce your heating costs, try thinking like the Japanese, and/or go solar.

msjawolfe |
Sat, 30/11/2013 - 17:43

I'm a bit surprised (or blind) as I didn't notice anyone addressing the use of an electric light. Did I just miss it? Seems like that might be a bit more practical and safer than using candles.

Undustrial |
Mon, 09/12/2013 - 22:54

While I suspect this would be a better heater than a candle alone (if only because it would keep radiating after it goes out), the posters above are right when they say it won't actually generate any more heat. With a little more design work, though, it probably could.

The key is to burn the candle more efficiently, which would mean both more heat and less soot. The two easiest ways to do this would be to get it more oxygen and to pre-heat the air coming in. Since warm air rises, any lit candle is already moving a fair bit of air around, just not in a very controlled way. Old oil lamps used to use a glass 'chimney' to guide air around the wick, creating a larger, brighter flame, just as rocket stoves use the same principles to burn wood ultra-efficiently.

If the candle burned inside the thermal mass instead of below it, the flame would burn far hotter - it could both channel and warm the air coming in. What about setting the candle inside a two inch steel pipe with a pot(s?) on top like a lampshade? Nuts/bolts/washers like those above could be used to hold the pot on and raise/lower it to play with airflow....

Sandra Dee |
Mon, 30/12/2013 - 19:23

Thanks for the science lessons. However, in case of emergency this city slicker living in Canada is busting one out! I would rather sit next to something giving off heat in a small room than be even more cold without it! Obviously there are some safety concerns but it looks harder to knock over and burn the house down than a candle burning on a candle stick. I saw a similar post with a metal loaf pan, tea lights, and two flower pots. It can hurt to have one if the furnace breaks down, the power is out for a long time, or you just need some extra heat in a specific area to make living a little more comfortable. How about adding this concept to the Crisco can candle idea I saw somewhere? - Not exactly permaculture now more like I.C.E. idea.

murray |
Fri, 03/01/2014 - 12:36

Perhaps an application for the flower pot heat system could in one's car. It is in the minus 30's in eastern Canada this winter and if one encounters car trouble on a long trip, this idea could be a life-saver.

ewbray |
Tue, 07/01/2014 - 18:02

Made a few modifications to the design!

Used an “orchard terra cotta flower pot” INSTEAD of a “standard terra cotta flower pot” for the outer pot. Those come with a hole in the bottom and four (4) slits on the sides near the bottom of the pot.

Blocked the hole in the bottom with aluminum foil held down with some old valve cover gasket sealer, that I had laying around in my tool box, now instead of the warmed air escaping out the top of the unit, the warmed air is distributed out the four (4) slits in the side of the flower pot thus spreading the warmed air in a more horizontal fashion for more evenly distribution of warmed air throughout the area!

Found a way to have a much more STABLE base for the unit. I used an old 10 inch cast iron frying pan instead of the bread pan or meatloaf pan. Then fitted an upside down 8 inch round metal basket inside the cast iron frying pan that raised the flower pots level slightly higher (approx ⅞ of an inch) than the cast iron frying pan's edge's level to let oxygen to get to the flames. The terra cotta flower pots can be secured to the metal basket with either thin wire or ball chains. The cast iron frying pan's handle also makes it easier to move the space heater, {if necessary}, besides giving it a low circular heavy base that is NOT going to be tipped over! https://dl.dropboxusercontent.com/u/10471230/Frying%20Pan.jpg and https://dl.dropboxusercontent.com/u/10471230/American-metalcraft black-round-wire-basket-8 in.jpg

To modify (compact) the source of heat, the next thing to do is to put vegetable shortening in an empty 5 oz or 12 oz tuna fish can and then put an old saucer in a frying pan that was half full of water. Once the water came to a boil, place the can of vegetable shortening on the saucer. As the vegetable shortening melts, vanilla extract or lemon extract is added to the solution; this gives the vegetable shortening candle a very nice aroma while it burns. Keep adding vegetable shortening and the flavor extract until the can is full to the brim.

Cooling the liquid back into a solid is best performed by either placing the can in the refrigerator and/or the freezer. After the solution becomes solid, push four (4) of the small birthday cake candles equidistant from each other into the matrix. The birthday cake candles supplies wicks that are better than any DIY homemade wicks.

By melting the vegetable shortening first, this REMOVES all of the air that the manufacturer places in the product during its production. This will help insure 5+ hours of burn time per oz. for each wick in the matrix.

Now there is one (1) fire unit, instead of four (4) separate fire units, that should give the user 5+ hours of continuous burn time with the 5 oz can and 10+ hours of continuous burn time for the 12 oz can with the flower pot space heater!

The 'secret' to good design of any device is to REDUCE the number of functioning parts down to the bare minimum!

If the user wants to stick more with the original design, the user could also make a {lamp oil and/or cooking oil} candle out of an old 2.5 oz. baby food jar X 4 and use those instead of tea lights since the user can get about 5 hours of burn time for each ounce of fluid! This way the user can refill the fluid candle bottles as needed and there is a much less chance of the heater being knocked over.

kttecatt |
Fri, 31/01/2014 - 03:58

We built this exactly as you specified, and then with some other size pots and more hardware. In all cases, while the pots did get warm, they did not radiate any heat into the room. As a matter of fact, I couldn't feel the heat on my feet, even with them up on the table, 2" from the pots. While I understand the premise of this project, it did not stand up to our at home test.

Ma8nolia |
Fri, 31/01/2014 - 18:28

Recently, thousands of motorists were stranded in their cars in Atlanta, GA and Birmingham, AL, which they then abandoned for warmth and food. Suggestions were made for storing mylar blankets etc in the trunk (bonnet, heheh) of the car. It might be nice to also be able to heat the car for a while with candles and with the window cracked, using no zinc material, as it is toxic, as is Teflon. I don't know of a safe way to put the housing into a car. Any suggestions for modification?

rebeltf |
Mon, 10/02/2014 - 10:27

I bet not one of the above naysayers have tried this before offering Bill Nuy Science Guy advice and/or admonishment.

This method indeed works and works well considering the DIY nature of the materials used , nobody said your going to heat your house or concert hall with these , they are meant for smaller room , spaces , tent , etc. It works , I've used them and made them as gifts , I'm using one this moment !

"Science" has been proven wrong many , many times , so put that in your pipe and smoke it. Maybe it'll keep you warm....

tomdunnavant |
Tue, 18/11/2014 - 13:34

I built the dang thing, and placed it over my gas heater, directly over the pilot light, the i monitored the temperature in the room, expected to get at least a couple degree bump in temperature. Not one degree, no improvement, no savings, but in the spring, i have three new flower pots.

jm beckers |
Sun, 08/02/2015 - 23:46

I saw this subject on a Dutch site, I didn't read all comments.
Combustion of wax will indeed give you an amount of heat, one can't change that. So heating a room with?
It is a matter of feeling.
A room heated with radiation heat (from a stove or some pots like this) will feel more comfortable at a lower temperature as one heated with air convection heating. The difference is 4°C.
It is also easy to imagine: you will feel the heat from these pots, standing 3 or 4 meters away from them. If you just burn the candle, you'll have to hold your hand above the flame to feel something.

emmawilson |
Wed, 11/02/2015 - 07:42

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