[MOTB2021]

I've recently been taking great interest in the DIY alcohol stoves I haven't been seeing many variations of on YouTube. I even did a couple of experiments to see what works and have gotten great results. But the designs I've been using are about as simple as you can get as opposed to others I've seen.

I started out with a tin can that green peas came in; a 15 oz can. I used most of the leg of an old pair of jeans as the wick because I heard cotton can be used instead of a roll of toilet paper. I added 10 ounces of 70% isopropyl alcohol and lit it, and it burned for an hour and 45 minutes and only smoked a little bit toward the very end. Today I tried to use it has a stove to heat up water. I used the same cotton in the same can but only added 1 1/2 ounces. After about 8 minutes, it started smoking a lot, so I put out the flame. By that time, the water was hot enough, although not boiling. I used it for my oatmeal.

Anyway, all my set-up consisted of was the can with the cotton/alcohol in it with an open top, 2 taller cans to the sides as supports, and then a can of water resting on top of those suspended over the alcohol can. I used another empty can as an improvised "lid" on top of the water can.

Since this seemed to work, I'm curious about other homemade designs that involve having a ring of little holes for the flames to come out the sides, or the top. Why not just have an open-top can, and then use other cans or other items to the sides to prop up the container to be heated? Do the holes somehow increase the temp. of the flame?

My setup was much like this guy's:

But the vast majority look like this. Why?

 

[paraquack]

When it comes to fire, I purchased my stove. But it was cheap, way back then.

Amazon.com: Alcohol Stove, Camping Stove with Stove Cover, Stainless Steel Windproof Solo Stove, Suitable for Outdoor Camping Hiking Backpacking : Sports & Outdoors

Amazon.com: Alcohol Stove, Camping Stove with Stove Cover, Stainless Steel Windproof Solo Stove, Suitable for Outdoor Camping Hiking Backpacking : Sports & Outdoors

www.amazon.com

 

[NMPRN]

I'm curious about other homemade designs that involve having a ring of little holes for the flames to come out the sides, or the top.

Have you looked at "penny" stoves? There are several versions, they all seem to work pretty well.

 

[Kauboy]

Do the holes somehow increase the temp. of the flame?

Holes provide for better ventilation, both intake and exhaust.
You can choke a flame out pretty quickly if it can't take in sufficient oxygen and also vent post-combustion gases.
Depending on hole size and quantity, there can be an optimal arrangement and flow rate for the best burn, resulting in an efficient and hotter flame. This will vary with each stove design.

 

[Spenser]

I've recently been taking great interest in the DIY alcohol stoves I haven't been seeing many variations of on YouTube

Technically that is not an alcohol stove, but rather a candle. The wick is what is giving off smoke, as alcohol doesn't 'smoke'.

For a stove, it is a very poor design due to lack of concentration of heat. NMPRN listed on for you that is an actual alcohol stove.

Personally I prefer using Tuna cans due to the thicker metal walls of the can vs a soda can. The size and placement of the holes are very relevant.
My suggestion is to get the following:
Goggles, Face mask, Fiberglass, soda can or 2 tuna cans, Drill and drill bit, Rotary tool with cutter bit (if using a soda can, a sharp blade would sulfice.

Goggles and face mask is due to working with Fiberglass, you do not want to inhale those particles while cutting it. The fiberglass mesh is to prevent the alcohol stove from spilling alcohol if knocked over. You will be inserting the Fiberglass into the soda or tuna can. You will be drilling numerous holes around the side uniformly to allow the fumes to create a 'burner' when lit, and another hole down the center to pour the alcohol in for refueling. It is called a penny stove as you use a penny on the hole in the middle to close off that hole.

This type of stove you will not have smoke, as no wick, and you will have a much hotter flame, and will last longer.

with regard to not being many alcohol stove videos, you are greatly mistaken of the numerous styles that are in youtube.

 

[Spenser]

Sorry, just noticed you were using 70% alcohol; for less amount of time used, Denatured alcohol which is about 95% alcohol, will result in a much hotter temperature, so it will bring water to a boil faster. It is recommended to use 90% or higher alcohol content for best results. "HEET" can also be used instead, which can be found at any auto-store.

The alcohol stoves that I own came with the 2 Stainless Steel Fondue pots that I bought years ago.
They have a variable temperature feature, and a cover to turn it off. The handle on these is what is used to regulate the number of BTUs produced. The more it opens, the hotter it will get, and the faster it will consume fuel.

I have also used my own DYI alcohol stove with the addition of an empty medical IV bag that I would fill with alcohol and use it as a reservoir to continuously keep adding alcohol while the unit is running. This requires drilling into the side below the flames and having a tube inserted into the burner.

 

[MOTB2021]

Holes provide for better ventilation, both intake and exhaust.
You can choke a flame out pretty quickly if it can't take in sufficient oxygen and also vent post-combustion gases.
Depending on hole size and quantity, there can be an optimal arrangement and flow rate for the best burn, resulting in an efficient and hotter flame. This will vary with each stove design.

In the case of the "penny stove", I can see the holes providing more even distribution, but how do they provide sufficient oxygen since the holes only provide a way for the flames to get out? Wouldn't there have to be holes elsewhere to provide for oxygen intake?

 

[Kauboy]

In the case of the "penny stove", I can see the holes providing more even distribution, but how do they provide sufficient oxygen since the holes only provide a way for the flames to get out? Wouldn't there have to be holes elsewhere to provide for oxygen intake?

That stove is not producing an internal flame.
The container is holding a fuel source. The exterior is then surrounded in a heat source (more fuel lit on fire) producing heat which vaporizes the fuel inside. The vapor rises from the holes mixing with oxygen in the air and being ignited by the flame that was already outside the stove. Eventually convection takes over and proper heat is achieved to maintain the flame even after the exterior fuel source is exhausted.
The fuel/air ratio is maintained at the hole. If the diameter of the hole were enlarged, the fuel/air mix could be too rich. If reduced, too lean. But there would be an optimal size for the hottest flame, given enough ambient O2 in the surrounding environment.

 

[NMPRN]

The hole size is surprisingly forgiving. If they're too big (or too many) the pressure can't build up and flame gets kind of weak and sloppy. If they're too small (or too few) the pressure gets too high and the flames shoot out like tiny blow torches and if the stove halves don't seal well you can get flames where you don't want them.

The stove in post #3 has about 20 holes and has a sloppy flame with yellow tips. My best stove so far (below) has eight 1/16" holes and burns like a small gas stove burner, nice blue flame with no yellow tips.

The five holes in the center are for filling the stove and get covered with a penny when the stove is running. ...hence the name "penny' stove.

 

[MOTB2021]

The hole size is surprisingly forgiving. If they're too big (or too many) the pressure can't build up and flame gets kind of weak and sloppy. If they're too small (or too few) the pressure gets too high and the flames shoot out like tiny blow torches and if the stove halves don't seal well you can get flames where you don't want them.

The stove in post #3 has about 20 holes and has a sloppy flame with yellow tips. My best stove so far (below) has eight 1/16" holes and burns like a small gas stove burner, nice blue flame with no yellow tips.

The five holes in the center are for filling the stove and get covered with a penny when the stove is running. ...hence the name "penny' stove.
View attachment 115229

I think I'll try making one like that in the next few days.
Now, can you tell me the difference between this and just using something like a small tin with alcohol and a wick in it to use as a stove? I found a video of a guy who did just that and boiled water in only 5 minutes. Does a penny stove do it even faster?
Here's the video. It's pretty short:

 

[NMPRN]

Now, can you tell me the difference between this and just using something like a small tin with alcohol and a wick in it to use as a stove?

I'm just guessing but I'd bet the penny stoves are a lot more efficient. They'll both boil water but I suspect the penny stove will do it with significantly less fuel.

They only take a few minutes to build, it's fun and it doesn't cost anything. Experiment a little and see what you think.

 

[MOTB2021]

Well, I went ahead and constructed a penny stove. However, it turned out to be a waste of time. I constructed it the way I've seen it done countless times on YouTube videos. This morning, I filled it with one ounce of 70% isopropyl alcohol, then put a small amount on the plate next to the stove and lit it. It didn't work. I tried it again with a little more alcohol. It still didn't work. So then I tried using even more, plus I put some on the top over the penny and lit both areas. They both burned for a couple minutes. During that time, I used a lighter to put a flame near the jet holes hoping to ignite the fumes. Still didn't work.

I could hear a gurgling sound, but I don't know if that was the alcohol boiling inside the stove, or if it was the alcohol on the outside of the stove making that sound. But after all the flames went out, I carefully felt the stove and it was very warm. I then tipped the stove upside down over a small pie tin to drain the alcohol. I was surprised how fast it poured out since it took a long time to get it in at the beginning. There was some steam coming off the alcohol, so it must have been warm. I ended up throwing a lit match into the pie tin and letting it burn under the water can I was going to heat up. It took just 4 1/2 minutes to get 1 1/4 cup of water boiling. I let it burn out after that, which took about 2 more minutes.

As I have always thought, the simpler method is more likely to be successful.

As for the construction, I noticed in the videos that people use a push pin by pushing and twisting with their fingers to puncture the aluminum to make the holes. I quickly found that to be hard and painful and ended up using a hammer to gently tap the pin in. That sure made that part much easier.

 

[NMPRN]

As I have always thought, the simpler method is more likely to be successful.

Go with what works best for you.

It might be your 70% alcohol causing the problem (... it's 30% water). I've never tried to use 70% so I can't say for sure. Any drugstore that sells 70% also sells 91% for a few cents more, and a bottle of 91% will create a lot more BTUs than a bottle of 70%. You can even get 99% isopropyl from walmart.com but that's probably overkill.

 

[Spenser]

Well, I went ahead and constructed a penny stove. However, it turned out to be a waste of time

It might be your 70% alcohol causing the problem (... it's 30% water).

Motb I mentioned bout 7 days ago not to use 70% just as NMPRN mentioned. Also, it would be rather helpful for those of us that have made penny stoves successfully to have a photo of what you did.

With regard to your setup, you seem to be doing the version where there is a basin of alcohol that heats up the stove then ignites the fumes. That one increases the temp of alcohol causing more fumes to emit. The ones that I made do not have that basin, and since I am using the correct % of alcohol, it works instantly.

Also the photo of your DIY stove may indicate that there is too much space from bottom to top, improper size holes, or distance between holes on top, a picture is worth a 1,000 words.

 

[MOTB2021]

Motb I mentioned bout 7 days ago not to use 70% just as NMPRN mentioned. Also, it would be rather helpful for those of us that have made penny stoves successfully to have a photo of what you did.

With regard to your setup, you seem to be doing the version where there is a basin of alcohol that heats up the stove then ignites the fumes. That one increases the temp of alcohol causing more fumes to emit. The ones that I made do not have that basin, and since I am using the correct % of alcohol, it works instantly.

Also the photo of your DIY stove may indicate that there is too much space from bottom to top, improper size holes, or distance between holes on top, a picture is worth a 1,000 words.

I agree about pictures being valuable. Here's mine:

 

[Spenser]

could you try testing this using 90% alcohol and see if it works, as that looks fine to me

 

[MOTB2021]

could you try testing this using 90% alcohol and see if it works, as that looks fine to me

I suppose I could, but I don't have any. I just have 70%. I'll have to buy the 90% to try it later.

There's something else I was concerned about. I heard that it's not good to get aluminum real hot because it supposedly releases toxins into the air or something. Since that's what these penny stoves are made of, it got me wondering about that. Here's a video where I heard that mentioned. Start at :35 seconds:

Also, I thought I'd add another pic. This one is more overhead to better show all the holes. Obviously, some of them show that the pin didn't go in exactly as intended.

 

[Spenser]

As I mentioned, the stove looks fine. The 70% ALCOHOL will produce less fumes from alcohol, which seems to be the issue here with your stove.

With regard to aluminum, you are correct about the metal giving off toxic fumes. This is why it is suggested to use copper mesh screens in tobacco pipes, as it can cause a condition known as blue lung.

The thing is, the temperature emitted from a Bic lighter is hotter than the alcohol burning in your stove. Also the flames are coming once the vapor is out of the hole, and there for you will not have a high concentration of metal vapors.

Also using a thicker aluminum metal such as a tuna can, would further reduce the fumes from the metal compared to a dosa can, but again, unlike an aluminum pan that leech into your food, any miniscule amount of byproduct from the can will be dispersed in a large area, and as long as your place is vented, you should have nothing to worry about health wise.

 

[MOTB2021]

My plan was to use such a stove indoors. That leads me to another concern in addition to aluminum fumes. It's soot that I see that forms on the bottom of containers I use to heat food and water. When did I look up the definition of soot, it states that it is made of particles from the incomplete burning of organic materials and is harmful if inhaled. But I've always heard that alcohol is clean and safe to burn indoors. If soot is formed on a pan when used for heating up food, then isn't it put into the air? When I see how much soot forms on a container after only 10 minutes, it really makes me feel concerned about how much of it is put into the air over the course of a couple hours or more if burned for heat. So, does soot actually go into the air when the alcohol is burned in a way other than a stove?

 

[Spenser]

So, does soot actually go into the air when the alcohol is burned in a way other than a stove?

There is no soot from burning alcohol & has negligible emissions. Chances are if you are seeing soot, it is from using 70% alcohol, meaning the 30% left has impurities. There is also another possibility, being the thin metal heating up is causing some soot from the paint on the can vaporizing. Try using sandpaper and remove the paint from top of your penny stove.