I ran 6 candles in about 4 inch terra cotta pots, 1 candle each. You get about 6 hours each, if you keep the temperature of the wax low that is. Hence 1 potfor each. When you run 10 hour shifts, and your only awake at home for maybe a total of 6 hours, it can help alot. Especially when you have a one room apartment with nothing included

In Eastern Europe there are still many flats & homes with much larger versions of this concept, only they're made with tile. It's a nice, gentle heat which does keep rooms comfortable.

I am always amazed at all the different clay pot heaters. The only benefit the clay pots provide is collecting the soot from the candles, and thats a good thing. You don't get any more heat than is given off by the candles. The soot actually builds up and will insulate the pot from the flame however all the heat given off by the candles goes into the room.

I've got one running now, and I'll tell you can use an old saucepan. Metal, of course is a terrific conductor, and just the same as the clay pot it traps the hot air and converts convection heating into conduction radiation heating. Just remember, the limitation is the candle.

Nice: you did the experiment correctly. Multiple candles in a small rather well insulated room without a high ceiling. When people slam these heaters, they need to realize the conditions of the test. In case of a power loss, they will not keep you warm and cozy, but they will keep you from freezing to death.

You should to another experiment using only the candles and no pots. See if the heat is the same with and without the pots.

Excellent video. Very well explained. Subscribed from a chilly U.K. A candle has a fixed amount of BTU’s. No amount of clay pots will change that.

I think you should repeat the experiment, without the pots... (with the same starting room temperature). That would really tell if the pots make a difference, or if it is just the tea light flames.

Ive made a few of those to save heating fuel. I like to enclose my desk and use one under there while working or spending time at the computer. It works wonderful and will heat the whole room eventually. Ditch those cheap tea candles and use a candle with a thicker wick and you will see a huge difference in the temp it creates. 👍

Try a UCO candle lantern (3 candles). Makes up to 5,000 btu's of heat, which will warm up a small room or tent. It's made to put out heat.

You had 6 candles lit in the room. Of course it got warmer in there. You don't need the clay pots for that. You should have tried it both ways starting from the same temperature, length of time, any power used in the room (lights), and see if there's any measurable difference at all. You'll find out the clay pots don't change how much the temperature in the room goes up. What they will do, however, is radiate more heat, which transfers to our skin better than convection from the warm air so it will FEEL warmer near the pots but the actual overall temperature of the room will still be the same.

Instead of the cylinder drill to separate the two pots use three small pebbles (or similar). That way the hot air rises inside the inner pot then down in between the inner and outer pots. The way you have it set up the hot air doesn't flow as freely inside the gap between the two pots.

*To those saying the clay pots don't add any heat -- you're right, of course.* But the experiment, as shown, still works. What the pots are doing, as they heat up, is to store the heat in a location -- the counter where the pots are located -- where we're able to be near it and make use of it (till the pots cool). If the clay pots weren't there and the candles were burning, the same amount of heat energy would be in the room (till the door opened, giving the heated air an escape), but all the heat would have risen to ceiling-height, above most people's heads... not a useful place for it to be.

Yes, the clay pot heater does work very well but be extremely careful as the melted wax has the potential to ignite and once that happens the flame can get easily out of control and set off the smoke alarm. Multiple small 5 or 6 inch clay pot heaters with a single tea lite candle is much much safer and better alternative to using a single big clay pot with multiple tea lite candles. Clay flower pots are extremely cheap and so are tea lite candles. If safety is a main concern then one should choose the single clay pot and single tea lite candle route.

I use 2 eight hour tea light candles under a plant pot the same size as yours, so 2 separate pots in my caravan & it definitely heats up my van in the UK. We're just going into winter so I'll see how good after the first cold snap, I can get 18 8hr candles for £2 so it's much cheaper than paying for gas, petrol or paraffin. I'm going to outfit my van with these pots this winter but knowing our government they'll put the price of candles up 😠 It definitely works though, you get much more heat than you would from the candle itself.✌️

That's so crazy! You can heat for 5 euros for like two weeks with that. I want to do van living when I put together enough money, this will come in handy.

Try again, but block the inside hole and leave outside hole open, this creates convection heat as well by. drawing air between pots as the inside pot heats up. Use a stove grate to set them on and/or maybe a metal sink stopper with holes on top of inside pot holding up outside pot, to allow that air flow. Also just watched making candles out of crisco to last longer. One commenter mentioned to be careful glass jars don't get too hot and explode, so why not get a smaller crisco can and stick couple b-day candles in it, and don't have to worry about exploding glass. It would be interesting to try an experiment using the air-flow type and the blocked air type. I have used this in a small RV and it does work.Pots will get hot enough to burn a round circle on a rug if ya take it off to check candles...ask me how i know, lol! This is a method everyone should know about r emergencies. Great job Phil!

I appreciate the initial use of the word "Emergency." I'm a 33 year HVAC professional and candles of all sorts put out more soot, and add pollutants to the ambient more than is readily apparent. This system DOES work, but there is no free lunch. I am concerned about unattended candles, and soot. Once, again, the presence of soot, and the degradation of Indoor Air Quality is not readily apparent. Regular, and often use of candles, when other heating means are available, is not generally a great idea.

Not sure what kind of lights you have in the room, but lights can heat a room up by themselves. The test should be done with the lights never on in the room, or the lights should be tested over time by themselves to see if they are affecting room temp(over hours).

They work aslong as the Room Area isn't to large. Add another one to a larger room, you may need 3 or more if the room is rather large or big. I would hang Drape or Blanket to cut the room size if you are running low on candles. Just remember to put a Paver under the Heater as not to burn or scorch your counter top. I like using my Terra Cotta Heater. Be Safe 🙏🙏❤️❤️

I would like to see you repeat the test just using the candles on top of the ceramic tile

The terracotta pots are only going to slow the heat from rising. Only useful as a personal heater in a small space. Something you could snuggle up near during a power outage.

Did this last year and the huge problem is the soot. No matter how often you trim the candle wicks they still like to turn sooty after a few hour burning and it is most noticeable when you blow your nose the next morning and see all the black you inhaled all night. I was using two pots with two candles and the pots themselves was encased in a long box with a fan on one end. It put out good heat yet the soot is not good for your lungs and wasnt worth it in my opinion.

This video is great! The most fascinating thing, though, is that picture of a moose behind you!

Don't place the candles touching each other. Space them a little ways apart.

You basically had a temperature increase of 3 degrees F over an hour or so (in an extremely small room). To make it really work you'd have to have quite a few of these clay pot heaters.

real practicle experiment ,you could even build this into a compact box with vents put it on castors and it would be portable around the home ,either way it far better than sitting in the cold ,good post btw .

Thank you. I was thinking of buying a double walled pot heater now I'm gonna buy one for emergencies

If you’re looking for heat transfer, fire to air, wouldn’t it be the same as letting those burn in the open?

So based on your test, you achieved a 3 degree rise in 3 hours. In a survival situation if you were in a room that size at 0 degrees F, after three hours it might be 3 degrees F. Wow, what a life saver.

Warning!! Always set these up in some kind of fire and heat proof tray! And always treat them as a potential cause of a house fire. I love these things and I have used a few different designs. They are great at taking the edge off on a really cold day. That said, remember the critical dynamic here: the candles are heating each other, just as much as they are heating the pots. If the candles reach their flashpoint, ALL the melted wax will ignite. When that happens you will have lots of little pots of flaming wax spitting every where, and a runaway heating reaction as all that fuel dumps its energy at a very rapid pace, potentially vaporising it too. I have seen some horror stories of people almost losing their homes, and in one instance their boat, because of this runaway reaction. My honest advice is ... NEVER leave them unattended, or sleep with these lit. Periodically check with a laser thermometer just to check the temps arent too wild. Assume they are a massive fire hazard Use a drip tray to contain any spillage/disaster Have reliable and instant means to put out a fire close by. These things are great fun, and a lifesaver in a power outage, but you have to treat them with respect. They are, after all, potentially a mini-fat fryer disaster waiting to happen. Thank you for the tests and careful benchmarking Phil

Now try it when the room is 45F and see how well that works. Hint: it doesn't heat the room up anywhere close to 60F much less 67F. If the weather outside is actually cold, and you have no other heating source, this won't work.

A more cost efficiant method is to use standard tabel candles. They burn twice as long and at 3 times the intensity so you only need to use 1. A batch of 50 costs the same as a pack of 100 tea lights so you end up with 4 times more heat per cost.

What does the clay pot add? Just burning a few candles would get the same effect wouldn’t it?

What is really effective is using a few pots threaded over a bolt. The last pot has a series of nuts and washers. I made one and it put out insane heat.

How much would the room heat up if you just burned the candles??

Oddly lower temperatures like 67f feel warm if warming from 66 but feel chilly if cooling from 68. The green lobby seem to have got most of the world accepting being cold now, normal indoor temperatures were 70-72 (21-22c) but now people are accepting 66-67.

Thank you for providing data, and ideas for one of these little heaters. I am curious about carbon monoxide and dioxide levels in a small room.

So, what is the temperature outside? What is the R rating of the walls of the room? How many of the walls are external ones? There are a bunch of things that would affect evaluating the efficiency of heating space this way

To those who say the pots don't technically add anything just burn the candles you're missing the point, the clay pots retain the heat so after the candles are spent the pots radiate residual heat. It's not creating more energy you're right but it's 'managing' the heat for a more even and prolonged release

It's facinating watching these experiments, as if by magic you are going to heat the whole room all over by 3 degrees C, it will never work. A few basic facts, hot air rises, you can't stop it. Putting a clay pot over the naked flame flame will slow it down a bit as it heats the pot up, but eventually, the hot air will rise up and heat the ceiling area. Hot air will not flow sideways, it will rise up. If you have a cold room, say the air temp is 3 degrees C, close to freezing, with any heat source such as the clay pot, the hot air will rise faster due to buoyancy because of the differential of the air temperature and hot air, just as on a freezing winter's day the smoke out of a chimney goes straight up vertically and fast. Get yourself a four poster bed with curtains on the top and sides and try the experiment again, you have a much air smaller space above the bed, and it will warm up quicker, but you may not wake up the next morning. Anyway, the average human body gives off 600 watts of heat which is probably more than a few tea light candles, so, get yourself a four poster bed and a thick duvet and you will be toasty warm , especially if there's two of you in there exercising.

Howdy. I truly apprechiate people who have persistance of vision and take the effort to experiment and publish for common good. Makes sense. Radiation heating feels several degrees warmer than the ambient. It warms where needed. One's skin and clothes. Regards.

Right on man! Thanks for testing this out. I'm going to do it at home. Anything to keep that furnace from kicking on earlier and more often. Thanks again.

a little physics lesson. Don't worry it won't hurt. You get about 270 btu/hr of heat energy from each of the 6 candles, thats 1620 btu/hr total or 475 watts of heat energy. That's the only source of heat energy in the apparatus. It's not a lot of heat energy. Consider: a small electric space heater makes 1500 watts of heat energy. So does a hair dryer. spoiler: use a finned copper plate instead of the terra cotta pot, and use a non-electric fan to force air through those fins. You'll get MUCH better radiant and convective heat transfer; making the best use of your candles heat energy. If you're not interested in the details, skip to the bottom and look at the heat loss calculator section. The terra cotta pots are a merely a landing spot for soot from the candles. They're not hot enough to contribute much to the spread of "radiant heat"; since radiant heat spread is proportional to the 4th power of the temperature in Kelvin. The terra cotta got up to 71C, or 344.15K, its 4th power is ~14,027,849,426 or 14 billion things (the units are not important to this discussion). If you replace the terra cotta with an ⅛ inch (3mm) copper plate positioned closer to the flames, the copper would reach a much higher temperature ... goal is 250C --- hot enough to sear a steak (or a finger). This is achievable since the flames of the candle may exceed 1000C. Aside: aluminum is a more economical choice than copper, but copper has a much higher thermal conductivity than aluminum [ copper = 400 and aluminum = 240] and will transfer 67% more radiant heat than aluminum. back to the temperature: 250C is 523.15K, its 4th power is 74,903,984,174 ... or 75 billion things. Thus the copper plate will be (75-14)/14 = 4.4 times (440%) more effective at spreading radiant heat than the terra cotta. But wait, there's more. Convective heat transfer is fluid flow across a heated object, in this case the fluid is "air". Convective heat transfer is proportional to the differences in temperature (object - ambient). With the terra cotta the difference is (71C - 20C) = 51C, with the copper plate the difference in temperatures is (250C - 20C) = 230C. So the copper plate is (230 - 51)/51 = 3.5 times (350%) more effective at convective heat transfer than the terra cotta. And more. Convective heat transfer is also proportional to the surface area of the heated object exposed to the fluid (air) ... that's why computer CPU coolers have oodles of fins (or pins). So rather than a flat copper plate use a copper plate with lots of fins (or pins). Aside: the design of optimal fins or pins layout is a hot topic in computational fluid dynamics (CFD). If you want to go down that rabbit hole google "CFD pins or fins" And still more. Forced convective heat transfer in air is up to 10 times (1000%) more effective than natural (un-forced) convection. So add a fan blowing air through those fins/pins on the copper plate (again like a computer CPU cooler) In particular add a non-electric stove-fan, they use the thermo-electric effect (they convert differences in temperature into electricity) to power the fan. One such fan (a 4 blade unit by Voda) starts spinning at 55C and is most efficient at 250C, but don't operate above 350C, it will damage the fan. Botton line ... use a copper plate with fins/pins instead of the terra cotta pot, and use a non-electric fan to force air through those fins/pins. You'll get MUCH more effective radiant and convective heat transfer. heat-loss calculation: There are lots of heat-loss calculators online. They ask about the size of a room, the insulation, the outside temperature and the desired inside temperature (maybe square footage of windows) ... and calculate the amount of heat energy required to achieve that inside temperature in btu/hour or maybe watts From this you can calculate how many candles you need, remember a candle makes about 270 btu/hour, or 80 watts. For example: a 16x12x8 room (LxWxH in feet), with "mediocre" insulation, 0F outside and 45F desired inside; needs 3550 btu/hour. That's 3550/270 = 13.1 candles. Note paraffin wax makes 19,900 btu per pound when burned. So you will be going through 24*3550 = 85,200 btu's a day OR 85,200 / 19,900 = 4¼ pounds of paraffin candles a day. If you buy paraffin in bulk (50 pounds) it costs $2 / pound. So $9 a day for candles. If you buy premade candles at retail, you will pay a LOT more. It you had a propane heater, you would need (58,200 btu/day) / (91,452 btu/gallon) = 0.636 gallons / day, which costs $3.69 a gallon (delivered), for a cost of (0.636 * $3.69) = $2.34 / day. Whether you use candles or propane or a wood stove ... make sure you install CARBON_MONOXIDE detectors. Carbon monoxide is odorless, colorless, it doesn't make you cough; it just quietly kills people.

good video im going to try this, since the energy prices have gone batshit-crazy - also its impressive and gratifying to discover that the President of the Ukraine finds time to make these helpful youtube vids ;)

Underfloor heating works very well because it's all over the floor, under the carpet and the heat rises slowly due to the close temperature differential between the heat source and the air temperature. Unfortunately it uses electricty to heat the cables and it's not the cheapest way at present.

Here's a bit of information for you. Six candles would probably give off more heat without the terracotta pots 👍🏼

Try again with the lights off. You don't need the lights on for the experiment to work. How many Watts were the light bulbs? Were the light bulbs energy saving, or LED?

nobody on youtube compares the effect to just burning the candles without pots. And your spacer, despite the hole, is still blocking the hot air bcs it almost touches to outer pot and warm air rises if not forced down or cooled.

I used three different size clay pots inside each other, on a clay bottom flower pot saucer , all pots bolted to a threaded rod with nuts and washer spacers. With three small feet (short bolts with nuts and washers. All drilled through the clay. Be careful drilling as the clay will pop out a crater when the drill comes out the other side. Drill just enough to see a small hole, then finish the hole from the other side. No craters ! I put one in my workshop on the floor close to where I stand. I noticed a difference in the temp. after a while. Cheap bag of candles from various stores too. Just shop around for the best prices. Cheap heat, lower electric bills and barely any smell !!!! FYI

It is like watching grass grow.... exciting

Thanks for sharing. I was laughing, I thought I heard an Alexa going off in the background.

yes it does! i use a double pot screwed together and i can say that it work well with me, the bigger the candle the better, bees wax is prefered. It is really a game changer when you lost electricity. Everyone should build one for those hard times. And also have a box full of candles in the closet.

1.4C increase in a very small enclosed room. Try it in a room that is twice that size at around 13C to start.

Since it is a very small space, I wonder how warm it would get from just being in the room without the candle. I know from experience working in a closed off bathroom that it gets rather warm quickly.

From my tries your pots look to high from the candles. To create a eating system, terra-cotta must be hot to redistribute the heat. But a specific pot designed specifically for heating can be considered as well.

I stuck one tea light in a Dakota fire pit in an area where I wasn't supposed to have a fire and stayed warm enough when I was right by the fire.

There's only so many BTUs contained in a tea candle's wax when burned. No amount of clay pots is going to alter that value.

The cap is supposed to be on the inner pot, and the outer pot should have the hole open. It's supposed to work by trapping the heat in the inner pot, and heating it up. Then the air between the pots warms and rises, out of the hole in the outer pot. Sucks in cold air at the bottom, shoots out warm air at the top. It's like the rocket stove principle. No idea whether it works with pots.

How many high output bulbs are in that room, did you start this in the morning as it heated up the ambient room...

I would like to see a controlled experiment of this pot v.s. just the candles. My bet is that just the candles heats the room quicker and last longer because of the colder slower burning wax. The pot is merely a safety shield to prevent fire but actually stops heat energy from getting to the air keeping a certain amount of it trapped in the pot.

I agree that you would need to try the experiment w/ only the candles. Also, you confounded it by leaving the lights on in the room; if they give off any heat at all (some LED lights do & incandescent most certainly do) they may have been responsible for the increase in air temperature. So see if the room temperature increases with candles only and with no electric lights. I'm no physics expert, but the little I do know says you only get out of a system what you put into it.

Very good video! Thanks. Could you use one Crisco oil candle in a glass jar, as well?

thank you for posting this. it all helps.

It raised the temperature only by 1 degree. That is not much if you have to heat up a room when the outside temperature is falling into the minus and you have no other rooms surrounding you. Also the bathroom lights give up a lot of heat, too. You should have turned them off. But still, interesting try!

Should try this from a cold room. Like if you got home and the power had been out all day

Okay, so this may be taking things a little too far but couldn't we find a way to use thermo-accoustic's to power the heating of the clay pots from external pipes OR from Fresnel lenses directing light from lamps in the home onto the pipes directing kinetic energy into the home from a diaphragm with magnets on it which in turn produces electricity from a spun wire, some sort of always on system?

This was done well but it needs to be don in the cold of a winter day... with a power outage you may also have a wind factor constantly dropping the whole house temp. I would also like to see how long it would take a small room to raise the carbon monoxide level. Thanks.

The combustion of paraffin generates the same amount of BTUs whether just the candles alone or with this contraption. Simple physics.

Try capping the inner pot or even not at all, you can create a convection effect that way which works better. I have the two smaller pots bolted together, I use a long bolt and get one of the candles straight under it to maximize heat but use enough nuts and washers to ensure the pots aren't touching, and then have a larger pot sitting over the top so the heat can rise up out the small hole in the large pot. I have a second set up with just two pots with no holes capped at all (usually cap the top hole with a coin for about 30 mins to begin with) which pours much more heat out the top and strangely less paraffin smell.

OK, very good video. You’re the first to actually shows the temperature that I found, but I thought it’s funny how you said three hours, but you watch only said 2

Executive summary: No.

Thank you

No, my heater broke and I'm waiting for part to come so my technician can get it fixed. I've tried this now and no is the answer.

Would be neat to see if you set up the pots were efficiently if you could use less candles. see David’s post below.

I watched a tea light flame jump out of the tea light onto my dresser and start a fire. Make sure you put tea lights in a protected container where the flames cannot escape!

Wonder how much the lights contributed to the heat buildup.

So the energy source is the wax in the candles. Exactly, how is this pot contributing to the room warming up? You just as well hang a rock above the candles or a ceramic tile.

and what would it be without the pots. it will be just as worm but not the radiant heat

I did this because my house lost power and my landlord told me I’m SOL so I’m doing this to try and warm up my apt that’s maybe 3x this room. I only got one pot though… I guess we’ll see if it raises my room/apt higher than 20 degrees F

Very interesting and easy to follow . Thanks

use carbon felt as your wick and vegetable oil. The carbon felt will wick up the oil. The wick will last indefinitely without burning up like the candle wick.

We don't use a heater. Hi from South Africa. Yup, our Municipality sucks. So, no heater or the power goes out. From experience a lot of candles (like 30 pilar candles) spaced throughout the living room does make a difference. Looks nice and a little bit warmer, even if it's just 18°C instead of 10°C. If you can afford to build a wood stove, that really heats up a whole house and feels like hot Summer heatwave if you're not careful.

It is just simply transferral of heat from one medium to another. Without the pot over the candle, that heat will disperse into the whole room. The clay pot can focus the heat into a smaller space.

And FYI - a tealight candle gives off "about" 35W of heat - so in this case a total of about 200 Watts from the device. A human gives off about 100 W of heat energy. Maybe your bathroom had very low-wattage LED lighting? If you were using traditional incandescent bulbs then their total heat emissions would likely have been as much as or greater than all six candles combined.

i've seen people posting these things over the last few days because of very low temps here and power outages. I wondered if it actually worked but this video shows me this thing is basically useless. doesn't heat enough to do anything.

So, with a few hundred candles you could heat water to make steam to turn electric turbines to generate electricity to power your city and become a millionaire!

You’ll need a room made out of a giant terracotta plant pot to get warm using this method

Is it worth it? 2 hours for an increase of just 2ºC in a small room?

I use those little candles, without terra cotta pots. Mostly for lights. But if am going to get a tiny bit of heat, I would go to Sams Club and purchase a case of Safe Heat for indoor use, and have a carbon monoxide meter just in case. A little camping stove with a grill on top, bit enough to use with small and or large terra cotta pots, and to heat up water. Let's be real, something this small will take around 1/2 to 45 minutes to heat up water. If you have bullion you can put it into the pot (depending on how big it is) 1 bullion for a small quart pot, a tad larger 1 1/2 package or cubes. At least your getting something. You can also fry and egg or bacon, but it will take more then 15 minutes. But ya have to make sure the area is secure and safe, where nothing can be knocked over. Then you might wind up getting heat you don't want (house fire). Keep a fire estiquisher around in the area you plan on heating yourself (no tents) or cooking. Keep an eye on that Carbon meter. It will tell you if carbon build up starts in your area. You need to ventilate.

OK. I think this is neat but my question is, how is this better than burning the candles to heat the surrounding air. The candles arent generating any more heat just because they are under a clay pot, so I don't really understand the benefit.

Conservation of energy….never had a physics course in my life, but even I know it’s about the burning candles, not about the clay pots.. The pots only add additional mass that must also be heated, in addition to the space you’re trying to warm. Add insulation around the space, not more mass to the space

I'm more impressed that you had the Armaf club de Nuit intense man 😂😂

Covered pot of water will do as well and be much safer !!

There is no magic way to make the candles produce more heat than they would just out in the open. Conservation of energy is a given.

But can it be duplicated in freezing weather, where this would be a more realistic setting for one to use this system? How long would it take to go from 32F (0C) to say, 45F (7.2C) (coats and other clothing and blankets could help keep it warm enough to survive)?

Will it give the same heat without the terra-cotta pots? Seems like a lot of work for a few degrees increase.

OK can someone please tell me why would anyone use tea-lights? They burn really fast. Why not use bigger candles??

Why do you need the metal spacer when the pots already have that space between them and why cover the top instead of getting a pot without a hole in the top?

thanks so much for giving us the facts