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Anybody who lives away from the equator knows that it can get quite chilly in winter.
Sometimes, central heating dies at the worst time, such as when it’s below zero and the roads are iced over.
I’ve had to chop emergency firewood in the snow because a tiny electrical part burned out in the furnace and a repair guy couldn’t make it out for several days.
We had plenty of candles in case the power went out, but candles aren’t great at heating up a room.
But what if there was something you could do with candles to more efficiently heat up a room?
Make a clay pot heater!
Read on to learn how they work then how to make one.
Why You Should Make A Clay Pot Heater
A clay pot heater, also called a terra cotta heater, uses one or more candles under one or more layers of clay to warm up an entire room (or to heat a tent!).
They’re efficient and eco-friendly. Plus they are surprisingly cheap to run, especially if you make the candles yourself (paraffin isn’t recommended here).
You also likely have the materials around the house already.
Candles should already be part of your emergency kit, even (especially?) on a budget.
So, let’s look at the advantages and disadvantages of a clay pot heater:
- Easy to make
- Radiates heat after the candles have gone out
- Safer than open flames
- You may already have all of the materials
- Doesn’t rely on electricity
- Burns oxygen and produces carbon monoxide (don’t use in an enclosed space!)
- Fire risk
- May not last overnight
- Not good in large rooms
Now, hold on a minute, I hear you say.
Candles suck at heating up a room! They’re only good for light.
How does adding a flower pot make them better?
I’m glad you asked.
Candles aren’t good at heating a room because of a concept called thermal mass, which is commonly discussed when talking about environmentally friendly building methods.
Materials with lots of thermal mass absorb heat, store it, then slowly radiate the warmth out when the air gets colder than the object.
Thermal mass is why your water heater doesn’t have to run every second of every day.
It’s also part of the reason why urban areas tend to be islands of heat, warmer than the surrounding areas thanks to asphalt’s high thermal mass.
Air, though, has very low thermal mass. It warms up quickly and cools down quickly.
Houses let air in and out. Otherwise. you’d run out of oxygen and suffocate!
Candles put out most of their heat into the air, which has low thermal mass.
Terra cotta, however, has a high thermal mass.
So the candles heat up the clay pot, which then slowly radiates heat outward.
It’s not going to be at the same level as, say, a rocket stove. But a clay pot heater will take the heat from emergency candles and make it last a lot longer, turning them into a small, portable, non electric space heater.
This can help you get through a cold night.
How to Make a Terra Cotta Heater
There are over a dozen ways to make a clay pot heater.
The basic idea is to put two or more flower pots upside down over some candles. This way the heat warms up the clay pots and doesn’t get blown away in a draft.
Just one pot isn’t effective enough. You also want to cover any holes in the pot, else hot air will go right through!
Make sure each pot is smaller than the last, with at least a half-inch gap (a full inch is better) between the walls when nestled.
But the pot shouldn’t sit so it’s encompassing the candle entirely. The candle needs to be able to draw air into it else it’ll smother and die.
So you need a base to raise the clay pots.
Something for the candles to sit inside of is a good idea too, to minimize the fire risk.
Here are two clay pot heaters, one you can slap together in moments and another one which requires, gasp, minutes!
Temporary Clay Pot Heater
You can throw the temporary clay pot heater together in a few moments. If anybody in your household does gardening, you may have everything you need already.
- Two or three flower pots, each one a different size
- Small baking pan (a bread pan works best)
- Cooling rack (or grill rack, or anything metal and similar)
- Four tea candles or a short emergency candle
- Something not flammable to cover the hole on the top flow pot, such as a coin
- Put the baking pan in an area away from flammable objects.
- Put the candles inside the pan and light them.
- Place the cooling rack on top.
- Place the smaller terracotta pot upside-down on the cooling rack, centered over the candles.
- Place the larger flower pot over the first one. Repeat if you have three.
- Cover that top hole with something that’s not flammable, like a coin or a ceramic plate.
Success! You now have a small non-electric space heater.
The clay will get hot to the touch before too long, but in my experience, not hot enough to burn you immediately.
Still, don’t place a stack of papers on top of it.
When you’re done, you can reuse everything with no trouble. And since it’s not electric, it’s all very portable. Just set it up where you need it!
Permanent Clay Pot Heater
This version involves permanently assembling three clay pots together for a more efficient operation so you can put it all together when you need to.
The video is a slightly more advanced hanging version.
- Three flower pots, each one a different size. Make sure they have a hole in the center!
- Two Bricks
- Terra cotta tray
- Threaded rod or a bolt, at least 6 inches long and smaller than the drainage holes
- 6 washers to fit the bolt
- 8+ nuts
Making the Clay Pot Assembly
- Add a washer then a nut to the very end of the threaded rod or bolt.
- Stick it through the hole in the smallest pot, from the inside.
- Add a washer then a nut and tighten it snug but not too tight. Too much pressure and the pot will crack!)
- Add a second nut then another washer.
- Stick on the second pot.
- Repeat steps 3-5 with the third pot.
- Add the last washer and nut.
- Cut off the rest of the threaded rod if you want.
Putting it All Together
- Put the candles in the terra cotta tray.
- Put the bricks next to the tray, parallel to each other.
- Light the candles.
- Put the clay pot assembly on the bricks.
You’re finished! Enjoy heating a small room using candle power when next your heat goes out.
Clay pot heaters are not the be-all and end-all of heating your home.
However, when the power goes out and it’s freezing out, a little bit of extra heat will help.
Terra cotta heaters may not be able to heat an entire house, but they can help keep a room warm for hours at a time. Especially smaller rooms.
Plus, they’re cheap and easy to make. What’s not to love?
If you need to cook something up while the power is out, don’t rely on those candles.
Try a solar cooker instead and save the candles for light and warmth.