Estimated reading time: 18 minutes
Whether It’s a Small Shed, a Garage, or Your Whole House, These Do-It-Yourself Heaters Really Deliver – But Be Careful.
Winter is here, and in spite of your best efforts, there’s always that one room that is too cold. Electric space heaters are the usual option, but they have some downsides. For one, they really burn up the watts. Most space heaters run at 1500 watts on their high setting, and our electric bills tell the tale.
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They’re also dependent on electricity. That can mean running extension cords to an out-building like a shed or detached garage, assuming it’s a reasonable distance from a power source.
There’s also the possibility of a power outage–which could last anywhere from a few hours to a few weeks–and that’s when alternative heat sources are no longer just convenient, but absolutely critical.
Many people depend on wood-burning stoves or pellet stoves to keep up the heat, but most of these heat sources are centralized to living areas rather than out-buildings. There are ways to distribute wood or pellet-fired heat to other areas in a house, but some spaces in a home just don’t seem to get enough.
Fortunately, there are some easy-to-make alternatives that can allow you to keep any space warm. These DIY heaters are simple and can often be assembled from materials you already have on hand.
They tend to be most effective in smaller spaces, but a lot has to do with temperatures that are tolerable rather than toasty. Even the smallest DIY heater can maintain a relatively comfortable temperature of 50° Fahrenheit. That’s sweater weather and it beats freezing.
In larger spaces, you may need a few of these improvised heaters. Just remember, the more open flames you spread around in any space, the greater the risk.
We’re going to explore three DIY heaters, but before we get into the materials and assembly details, we should cover a few points on fuels, fumes, safetyand heat exchange.
Two primary fuels are used for the heaters we’re going to cover. Candles and a 70% solution of Isopropyl alcohol. A third possibility is a gasoline additive known as HEET, but it can produce an odor if the heater is not burning properly and is more flammable than a 70% solution of isopropyl alcohol.
The candles should be made with unscented, undyed wax. The smell of vanilla might be pleasant for an hour or so but can become a bit overwhelming as the hours wear on. We’re going to use plain white tea candles because they burn for 4 to 5 hours. The small metal cups surrounding the candle at the base also add a safety factor.
Isopropyl alcohol can be bought in most any pharmacy and many hardware stores. The proof varies across basic concentrations ranging from 50% to 91%. A 70% solution is ideal because it burns clean and will keep a steady, hot flame. Goldilocks will be the first to tell you that 50% is too low while 91% is too high, but 70% is just right.
A wick is used to draw the alcohol to the flame and this wicking catalyst is usually fireproof insulation material or, believe it or not, toilet paper.
Anything that burns gives off various gases. Smoke is the most noxious and usually the result of burning carbon-based fuels. Fortunately, isopropyl alcohol and candles give off little if any smoke and the fumes are relatively harmless.
The one caution has to do with the consumption of oxygen within an enclosed space. Any flame needs oxygen to burn, and a flame that starts to dim for no apparent reason is telling you something. It either needs more fuel or more oxygen.
It seems contrary to the idea of keeping the cold out, but some degree of ventilation is recommended even if all it means is opening the door now and again.
Open flames present obvious problems, so common-sense and due diligence are necessary here. It’s fair to say that many of us burn candles from time to time without harm, but the heaters we’re talking about will potentially be burning with an open flame for some length of time.
That’s why the location of your DIY heater is so important. It should be away from walls, drapes, beds, and any other flammable materials. It should also be in a location where it won’t be knocked over.
You should also develop a good insulating layer between the base of your heater and any surface, especially a wood surface. Temperatures in some of the spaces in these heaters will range from 200 to 400° Fahrenheit. Paper bursts into flame at 451° F, and 400° is getting close.
Typical insulating materials include brick, tile, or a layer of stones underneath the heater. A double layer of these materials beneath the heater is also wise as it will further disperse the heat.
One of the concepts that increases the heat for one of these DIY heaters is a simple heat exchanger. A furnace works on the same principle.
A large slab of metal or ceramic is heated and then air is forced over the hot material to cause a heat exchange. As you’ll see in one of our homemade heaters, we’ll be using terracotta flowerpots to exchange heat with the surrounding air.
A good example of basic heat exchange can be found on the iron tops of wood-stoves. They’re often decorated with cast-iron objects in various shapes to allow the heat from the iron firebox to transfer to the cast-iron decoration and to the surrounding air.
If you ever see an iron duck resting on top of a wood-burning stove, you’d be wise to avoid grabbing it. It’s very hot, and heat exchange is the reason why.
DIY Emergency Heaters
1. The Tin Can Heater
This DIY heater is simple to assemble, it’s easily and safely stored, and it kicks out a lot of heat. It produces a fairly large flame, so location is critical. It’s also a potential hazard if it’s knocked over. There is isopropyl alcohol in the can and any spill will burst into flame, so be careful with this one.
You’ll also find that an alcohol flame is difficult to see in daylight.
Make sure everyone knows what’s going on so they don’t accidentally touch or knock over the heater because they couldn’t see the flame.
The can is a 1-quart paint can and should be a new, empty can. You can buy them at most hardware stores for about $3. Don’t use a can that has any residual paint in it. The paint will give off toxic fumes while the heater is burning.
Splurge and spend the three bucks to get a clean, new can. A 1-quart can will burn a little over an hour until it needs to be refilled. Don’t refill the can until it has fully cooled.
An option is a metal soup can or another tin can. The can should be well rinsed, and the paper label and the line of glue removed as well. From there, the principle is the same as the paint can except you won’t have a tight sealing lid for extinguishing, storage, and future use.
Materials and Tools:
- 1 empty 1-quart paint can with lid or empty food can
- 1 roll of toilet paper
- 1 bottle of 70% isopropyl alcohol
- A flathead screwdriver
- Use a screwdriver and your hands to remove the cardboard tube from the center of the toilet paper roll.
- Once the tube is removed, squeeze the roll so it collapses in on itself.
- Slowly insert the toilet paper roll into the can.
- As you approach the end of the roll, you might need the screwdriver to get it past the rim.
- Make sure the toilet paper is below the rim of the can.
- A large tile at least 1-foot square should be placed under the can.
- Slowly pour the isopropyl alcohol onto the toilet paper wick until it is saturated.
- Light the top of the can,f but be careful if you place the can in a bright area. The flame can be difficult to see.
Place the can in a safe location. The can will get very hot, so extinguish it and let it cool before touching. The lid can be slipped over the top to put out the flame. Seal the lid with light taps from a hammer and store where you store other flammable materials like kerosene, gas, oil, and propane. Before using again, top off the can with more isopropyl alcohol.
It may surprise you, but the toilet paper will not burn. It acts like a wick drawing alcohol from the bottom of the can. However, if too much alcohol burns off, the toilet paper could begin to char. When the alcohol level gets low, extinguish the flame, let the can cool completely, and refill to the proper level.
2. The Flower Pot Tea Candle Heater
It seems absurd to think that one tea candle could produce enough heat to heat a room, and you’re right. It takes 4 to 6 tea candles to do the job. What makes this tea candle heater work is the heat exchange concept. Terracotta flowerpots fulfill the role of heat exchanger, and over 20 to 30 minutes, they will get significantly hot from the small flames of a few tea candles.
This is another DIY heater that needs to be located carefully. The good news is that if it’s knocked over it won’t spread flaming alcohol, but melted wax is highly flammable and open flames are open flames.
- 1 4-inch diameter terracotta pot
- 1 6-inch diameter terracotta pot
- 4 to 6 plain white tea candles
- A large tile to isolate the heat from any surface and support the candles
- Smaller tiles or bricks to support the flower pots
- A quarter to seal the drain hole in the smaller pot when inverted
- Build up the smaller tiles on the large tile so they can support both flower pots and create enough air-space to keep the candles burning under an inverted pot.
- Center the candles and light.
- Invert the smallest pot so it is over the candles.
- Cover the hole in the bottom of the smallest pot with the quarter. Do not do this with the second, larger pot.
- Invert the larger pot over the smaller pot.
In 20 to 30 minutes you will begin to feel significant heat from the sides of the large pot and from the open hole at the top. To extinguish, blow out the candles, but be careful with the pots. Internal temperatures have been measured up to 400° Fahrenheit in the small, inner pot. Give them sufficient time to cool before handling.
There are backup alternatives to flower pots. Maybe the best is a cast-iron Dutch Oven inverted on the tiles or bricks in place of the flowerpots. You won’t have the convection that a flower pot within a flower pot creates, but the cast-iron will definitely get hot.
3. The Soda Can Jet Burner
This heater is an alcohol burner on steroids. Due to its compact size, it can be used in place of tea candles in the Flower Pot heater. One of these heaters under a flower pot will do the trick, and two will double the heat. However, this heater will also give off heat on its own, so flower pots are optional.
The assembly is a little complicated compared to the other two heaters, but the materials are very easy to find around the house.
Materials and Tools:
- 3 empty and rinsed aluminum soda cans
- A handful of fireproof insulation or pipe wrap insulation
- 1 bottle of 70% isopropyl alcohol
- A penny
- Kitchen shears
- A pushpin for punching the holes
- A small hammer of anything that can be used to pound the pushpin through the thin aluminum
- Work gloves to protect your hands from the sharp edges of the aluminum
- Permanent marker
- A small piece of a 2×4 to guide the marker on the can before cutting
- Needle nose pliers
- Put the can down with the bottom up and using a nail, carefully drive the nail through the center of the bottom of the can.
- Using a pushpin, make 4 holes around the nail hole. Use the small hammer to help drive the pushpin into the aluminum.
- Use the same pushpin to make 16 evenly spaced holes around the ridge at the bottom of the can. To do this, start with one hole and go to the opposite side of the can for the second hole and continue in this way to create evenly spaced holes.
- Split the difference between the two holes and punch again. Keep splitting the difference until you have 16 evenly spaced holes.
- After the holes are punched, rest the can against the 2×4 with the board lying flat. Hold the tip of the permanent market against the edge and slowly rotate the can to draw an even line around the circumference of the can. Repeat with the other can.
- Cut a starting cut on the can using a razor knife.
- Use the kitchen shears to cut the can along the line around the circumference.
- You now have the top burner section complete.
- Repeat with the other can and, using the needle nose pliers, twist and crimp the can every half-inch to make it easier to insert into the top portion of the burner.
- Once you have both cans’ bottoms cut and the top punched, you’re ready for the insulation wick.
- If using pipe wrap insulation (which is a cheap way to pick up some insulation), cut it the long way to the height of the base can.
- Roll the insulation and stuff into the base can.
- Carefully place the top can over the insulation filled base to fit together.
- Press the top down gently until the cans are tightly joined. Pour the 70% isopropyl alcohol into the top and allow to percolate into the can. You could also use a gasoline additive like HEET, but you’re probably better off with the alcohol. You’ll have to repeat this filling step numerous times. Lift the can from time to time to assess the amount of alcohol it’s holding.
- Using your kitchen shears, cut the bottom base off of the third can along the rim.
- This bottom rim can now be used to extinguish the flame.
- To get the can kick-started, pour a little of the fuel around the base of the heater to raise the temperature of the metal and encourage rapid evaporation. Remember to have a slab of tile to protect any surfaces from the flames. Light the top of the heater and the fuel around the base. If necessary, repeat the lighting process a few times to get the burner started. Wait until any flames are out before adding any alcohol to the heater or the tile base. You should also be careful to watch for any phantom flames. Alcohol burns with a dim, blue flame and can be very hard to see.
- Once the can is starting to flame through the perimeter holes, let it burn for a few minutes. Some holes will not be lit but they should catch flame soon.
- When a good number of the rim, perimeter holes are flaming, toss the penny onto the can to seal the center holes. Center it in place with a screwdriver.
The heat from this tin can heater can not only be used to heat a space but to cook with a setup that will support a pot or pan. It also works very well with the terracotta flowerpot setup.
Points to Ponder
These DIY heaters work, but they can be dangerous. Here are some tips for managing an open flame.
- The floor is a really bad place for an open-flame heater. It can be easily knocked over by a careless step, an over-anxious pet, or someone knocking something over and into it.
- Think about how you currently manage open flames in your home.
- Most people understand the importance of a fireplace screen in front of an open fire.
- Gas ranges isolate the blue flame at waist height in an environment typically surrounded by metal.
- Candles usually occupy the center of a table or in sconces on the wall.
- Even space heaters are usually set up away from walls or furniture and really shouldn’t be placed on a rug.
- Be mindful of ventilation. Open flames burn up oxygen rapidly. However, many of us cook over gas range tops with no apparent effect, but if your paint can heater is burning for a long duration it might be time to think about opening a door or window.
- Don’t go to sleep with one of these open-flame heaters blazing away. Anything can happen, although the tea candle and flowerpot setup may be the most benign if properly placed and insulated from any surface.
If you’re planning to use these heaters on a regular basis, you might want to think about stockpiling things like cans, isopropyl alcohol, tea candles, terracotta flowerpots, and a piece of fireproof insulation.
Hopefully, you’ll only use them for a short-term trip to the shed or the garage in winter, but if they become your only source of heat, you’ll want to be ready.
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