Hey guys, I'm late to the party on the original thread that got closed, but I'll offer my personal experience with them:


I hang out on weekends with some like minded friends and we do get togethers where we eat something new from our stores to see what works and try to get a prep related craft project knocked out before The Walking Dead comes on. A few months ago, it was my turn for the project idea, so I looked online for pot sizes and tips and didn't get very far so I winged it. I went and got two sizes of terra cotta pots that would fit inside each other, some stainless 1/4-20 bolts, washers, and wingnuts. Nothing fancy, just a few bucks to try it out and see if there was any validity to the concept.....

We've done some cool projects (PVC Bows anyone?) and this one ended up right up there with the best of them-no real planning on my part, I just picked what 'looked about right'. I knew that a single candle wouldn't be enough to do the job, so we went with 3 tea light candles. I tried the liquid candles too, but it gets so hot under the pots that they melted and nearly caused a serious fire, so those are out.... It takes about 20 minutes for the pots to get hot and start radiating heat, but they do work. I wouldn't count on just one to heat a room, but three might take the chill off. A single flower pot heater will keep your legs warm under a desk, but the real utility of these things is if you have no heat and can put under you while you are sitting in a chair wrapped in a blanket. That almost gets you too hot. We're talking toasty warm for the cost of three candles burning. The pot gets so hot you can't touch it-it literally becomes a radiant heater.  

I haven't revisited that project lately, but I plan on making a special base and wire mesh cage to improve the fire safety/burn prevention to make them better suited to being placed under a blanket as a personal warmer. I can totally see myself sitting under one of these things in a dead of winter power outage..... No idea how many it would take to make a room comfortable, but as an individual heater, they DO work.

If you can accept that they aren't a Mr. Heater Buddy and are willing to risk a few dollars to slap one together, I'd recommend trying it

Can you post a photo of this contraption?

I did this awhile back but found the candles didn't get it hot enough.  I used sterno and that got it hot as heck which was what I was looking for.  Pics of your setup?

you can put a coffee pot on top of that and have fresh brewed PDQ..

ETA: There is a washer between them too, you don't want to torque down on the pots very hard, the washer in the middle is just a little insurance-it would be easy to break these, especially after they start to grow with heat. Just tighten the bolt enough that it holds it together.

We found that the height of the flame relative to the bottom of the pots was fairly important to how hot it got-too low and the candles would suffocate, too high and the heat would go around the base of the pot. There is enough room for a 4th tea light candle, but I haven't tried it myself.

What would be cool is to incorporate a vegetable oil candle/lamp into these. No idea if those are stinky or not, but being able to use expired oil from your stores as heat and lamp oil could be pretty handy.

Where do the flames pull the oxygen from, if the base of the pot is presumably against the ground? And forgive me if this is a stupid question, but what is the point of the second pot inside the first?

The pot doesn't actually sit on the floor, it needs to be up a ways to get oxygen.

Thank you for posting this.  I wish you could have gotten in before I closed the first thread.  This is exactly the analysis I was hoping for.

With a tea light candle, propping it up with chunks of 2x4 was pretty close to optimum flame height.

Even with 4 candles it won't out perform one flat wick oil lamp.

Correct. I need to do some experimenting and find the best heat to money solution.

Exotac hot candletin?

I don't understand how the pots make the candles put out any more heat.

The flames put out "x" BTUs.  That is radiated into the area. The pot would absorb those and possibly change the timing of when you start and stop feeling the radiated heat but I don't see it increasing the amount.

Maybe someone smarter than me can explain.

I did buy my boy a Dietz lantern a few Christmases ago that came with a small cook pot and grill that fit on the top. He got a kick out of warming a cup of soup on his lantern when we'd go camping.

First, that sounds like a fire just waiting to happen.

Second, I wonder what the result of just wrapping a blanket around you would be.  Hell, if you're sitting in a typical kitchen chair and wrapping you & the legs with a blanket, you could stick any candle in there -- minus the pot -- and the heat will be contained and radiated to your ass.

The flames don't put out pure radiated heat, they radiate a small amount of heat but most of it is conducted/convected up in the form of hot air. That hot air rises straight to the ceiling. The flower pots "catch" that hot air, taking most of the heat out of it, and the pots then radiate to their surroundings.

Do the pots increase the heat output? No
Do they change the output into a form that gets more heat into a form that a human can "feel"? Yes

Those that are arguing that the pots don't change the heat output in BTU's are right. But the pot does make it so that you can better "feel" or "absorb" the heat that the candles do put out.

How do you define "work?"

They transform heat and light (to include infrared radiation) into latent infrared radiation by warming the pot up.

It will not warm up a room any more than just burning the candle. It will, however, be transformed into a different type of heat. There will be energy loss in transforming it. The law of thermodynamics doesn't make exceptions.

So again, it all depends on what you're defining as "works." You can warm a small area of your hand really hot with a tiny flame or a larger area warm using a radiant heater.

They don't. Someone that slept through physics figured it out and wants a nobel prize for it.

In reality, energy is simply transformed. It's never going to heat the mass of air in the room any more than the candle burning beside itself would. Either way puts out so little heat that the walls of the room will cool it down before the air even gets warmer.

The most efficient way is to use a fuel that gives off more BTU per unit of fuel consumed. Propane, kerosene, wood, coal, etc.

There's simply no way around that. Good insulation is the only thing that "helps" as it traps in the heat and takes longer to equalize with outdoor temperatures.

There's a YouTube video that goes over 10 more efficient means of producing heat.

Candle heater is an interesting project but is not an efficient means of generating heat.  Not enough BTUs / cost per therm

And the pots themselves warm the surrounding air that then rises to the ceiling.

Unless you are touching the pot, the net effect is the same in a closed space.

Technically, you are warming LESS air than before as you had to heat the pots first. Whereas the mass of air in the room would have absorbed that heat, though it would be negligible in both instances.

And, yes, the net effect is the same. Useless. ;)

A candle is never going to get a flower pot hot enough to radiate very much heat.
The heat leaving the flower pot will be by convection and conduction, just like the candle.

Stefan–Boltzmann law
From Wikipedia, the free encyclopedia

The Stefan–Boltzmann law, also known as Stefan's law, describes the power radiated from a black body in terms of its temperature. Specifically, the Stefan–Boltzmann law states that the total energy radiated per unit surface area of a black body across all wavelengths per unit time (also known as the black-body radiant exitance or emissive power), j^{\star}, is directly proportional to the fourth power of the black body's thermodynamic temperature T:
j^{\star} = \sigma T^{4}.

I don't think anyone is saying that a couple of flower pots can magically amplify the caloric heat output of a wax candle. When you light a candle, the heat goes straight up and dissipates, warming the ambient air. When you use 3 candles to heat up the flower pots, the underside of the pot traps the hot gasses from the candle and forces it to heat up the flower pots. The pots then become RADIANT HEATERS, i.e., they put off infrared energy themselves. It's not "more" energy than the input power the candles made, it's just trapped where it can do some Work.

All I can say is: Go spend a few bucks to try it and tell me that you don't feel heat next to the pot after you give 3 or 4 candles a chance to warm it up. Like I said, it won't replace a heater buddy, but it will keep you warm in a power outage in cold weather if you put it under a blanket and sit with it.

....maybe you missed the part where I said I wanted to refine it to make it safer.......

You could try it out and see, but I don't think it would be as effective. The candle flame is going to want to travel straight up and thru the blanket-sure, it will warm it up a bit, but the pot will radiate heat all the way around. You just have to try it for yourself.

I knew I was taking a chance posting this thread, I'm not going to get into thermodynamics or start comparing shoe sizes with anyone. My original post was, as stated, to share my EXPERIENCES with them and relate what I had found. They Work well enough for me to have one around in the event of a power loss, and that's good enough for me.

I stated that one of these will warm your legs under a desk. I stand by that.
I stated that 3 of these will take the chill off of a room. 9-12 candles WILL have an effect on room temperature. I stand by that.
I stated that one of these with three candles will make you toasty warm with a blanket over you and the 'heater'. I stand by that.

"Works", as in Works For Me. You can build your own and come to your own conclusions.

Very true, but we're not talking about heating a home or bug out cabin with these things. Think of them as personal heaters with a low output, no smells, and a loooooong run time.

......unless you are standing next to it and getting your skin/clothes warmed by the heat coming off of the ceramic.

You're right. The whole flower pot heater thing on the internet is some big April Fool's joke.

I don't think anyone in their right mind is going to tell you that a flower pot heater is the last word in creating warmth, but for some applications, they work within a narrow set of parameters.

I see. I get warm wearing a blanket. Adding more heat by me will be felt. At the end of the day, 9-12 tea light candles will have negligible effect on room temperature. Larger candles will obviously do more just because of more fuel.

As a cheap little radiant heater for just yourself, sure it can work. :) However, I'd recommend using this http://www.clickithotpacks.com/how-they-work.html and a blanket. Easier, warmer, and reusable

I've tried them. They get fucking warm and are great for being in a tree stand or office chair in the morning before it warms up.

As for heating a room, I still stand by there are much, much more efficient and quicker ways to heat a room. I get the experiment and the original intent, I really do. :)

Go buy those warmers, by the way. Awesome for survival scenarios or the outdoors. You "click" a button in the bottom that activates the gel and it heats up quick and stays hot for hours. It'll eventually cool and you simply boil it to reset it.

Nope, you still don't get it. Build one and try it and get back to the thread, or don't.

The heat from the ceramic can only reach you by warming the air betwixt.

I'm not trying to knock you - but this is one of those experiments where the outcome is readily predetermined by basic laws of physics.  I get that you want to test it, which is great, but your efforts would be better spent on a different heat source.

No, you still don't get it.

You can get all Thoreau and ignore any law you want, but the laws of thermodynamics care little of your attitudes towards them.

I guess I just don't get it.

I know, let's go into identical cabins up by you. You take your 9-12 candles and pots and I'll take a propane heater. We'll see who gets through the night and day.

Nope, the energy leaving the pot is in the form of Infrared radiation. That's why they call these radiant heaters. It doesn't warm the air by itself.

Build one, play around with it. Worse comes to worse, you have two pots to start some herbs in the spring and a couple of extra fasteners to put in your garage that you'll need sooner or later anyway.

Nope, you still don't get it.

I never said that it would warm a cabin. I said several of them (3?) would take the chill off of a room. Not "Warm a room in the dead of winter so you can take your sweater off".

Go back and read what I said.

Guess you don't get a joke

How can there be energy "loss"? Does conservation of energy not apply here? But you said there were no exceptions... now I'm confused...



Yes, the pots heat surrounding air, but I will bet you cash money that they radiate more heat than a candle flame, which means they cannot possibly convect more heat than a candle flame (that whole conservation of energy thing). Just like I said, they are transforming energy into a form that is more easily felt by your body...


"net effect"... what is the net effect you speak of? I disagree but I'd like to hear where you're going with this...

Wasn't knocking your project.  They are pretty neat and a cool rainy day crafts project.  

Of course it applies. (additional heat) Energy is "lost" through the conversion from convection and light into radiant heat. It's a net loss of BTU, only slightly, but a loss nonetheless.

I didn't say energy was destroyed, which is what the CoE law applies to. Nice try, though.

I.don't care what anyone who.hasn't tried this says, it takes the chill of in my basement.  So obviously there is something to this.

That sounds like a progressive or a jedi knight

Ignore all facts rely on your feelings. Very sad.



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Yes, the lesson here is simply physics. Temperature IS relative. Cheers.

You know, shit like this is why I don't post much in this forum anymore-if I wanted to be talked to like some asshole in GD, I'd be there right now.

I used to be a regular cool-kid contributor in the SF, participated in many of the campouts, and shared a lot of my experiences as I matured from single apartment dwelling dude 10 years ago to homeowner with a rural BOL and a prepper lifestyle. The problem with the forum was the slow increase in Signal to Noise ratio-this post is exactly what I am talking about.

Call me a liberal hippy, call me sad, IDGAF. I actually DID something and took the time to share and relate my experience with it. You on the other hand are spouting off about something you Read about.  Who's the idiot?

I'm pretty sure this thread tips the scales in signal to noise. As its completely noise because you are dismissing the facts presented here.

Btw if you want to start talking about thermo classes and how much we have each taken vs reading I'm game.

Your appeal to your former greatness in the sf is a red herring in your argment. Basicaly you have said nothing but appeal to emotion

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Whatever, I'm going to have dinner with my girlfriend.

By candlelight?







It's all good here TOD - nothing wrong with a healthy round of comparing practice to theory.

I've never thought these would work as a room heater but using them as a personal heater like you describe sounds like it would work. The fire hazard would be the only drawback I can think of. I'm interested to see how you improve the safety.

Again, why is this crap not getting moved to GD?  Are we going to have an argument about perpetual motion, free energy, and bigfoot, just because some people don't understand basic science?  This kind of thread is why this forum has gone downhill over the last few years.  Used to be good information, now this kind of crap fills the space.

I looked up the BTU and wattage of a tea candle. They produce about 75w and 263 BTU, so 3 would be around 225w. I built a trash can oven for baking cosmoline off rifle stocks that uses two 200w light bulbs and it almost burns the cosmoline out of the stocks. I started with 600w and it was too much heat. I'm going to bet 225w sitting directly under you while you are covered with a blanket trapping the heat would keep you warm. Would it heat a house or a room, no way but I don't think the OP ever said it would.



 

I've built one of these before.

They are a neat way to make a very small heater out of pots, and tea lights can be found very cheaply at time, especially near the holidays.

They might heat a very small room, like a bathroom, but otherwise not to useful overall.  

Still a fun project to make and learn from.

I'm wondering how the sterno can would work instead of tea lights.