Furnace idea.

[mikeschn]

mike, I'm wondering how you joined the boxes together at the holes. do you have some boards or something between the boxes?
the two candles in the first box have most of their heat concetrated on the roof of their box, the more you can trap the air in the top of the boxes the more heat will be trapped from the air and transfered to the metal and then into the trailer
josh

Josh,

I am using 1/4" handibacker...





Mike...

[rowerwet]

I think I just talked myself into adding a below floor, candle-box heater to my tear...

[mikeschn]

I think I just talked myself into adding a below floor, candle-box heater to my tear...

Hey wait, don't run away. I wanna add one too!

I was thinking, we need some deeper tins. What if we grab the ones that are about 4 x 4 x 5" high. And instead of a square, if we line them all up in a row. So the heater is now 4 x 16". Then we just need to find a cold air return that can cover a hole, 4 x 16. Voila' a modern looking register, cranking out heat like it was in your house...

Mike...

[mikeschn]

Gee Mike, you did it now! Rowerwet is probably out in his garage, building an in floor candle heater for his teardrop.

Well Rowerwet, when you get back, we'd like to see some pictures!!!

Mike...

[Esteban]

For anyone who wants to try this one place you can buy square and rectangular cookie tins in various sizes is here: e-cookietins.com/tins-cans/rectangles-squares-shapes They are made in the USA.
It is fun to see Robert's inventive heater idea take off (catch fire, heat up?) and the improvements proposed to it.

[tac422]

It seems to me that the hole with the "X" should be eliminated ?

[KCStudly]

Looks to me like that hole is only in the tin and not in the dividing board, so no harm no foul.

[Esteban]

I woke up thinking about conduction, convection and radiation. Three ways heat is transferred.

The thoughts lead me to wonder how to make the cookie box heater work well/best.

Conduction. To reduce conducting heat through the wall of your teardrop you need to reduce direct contact of the back of the cookie tin heaters to the wall of your camper. Maybe by having a standoff between the back of the cookie tins and the hardibacker board that is up against the cabin side wall to create a small (insulating) air gap. The standoff might be small pieces of the hardibacker. Insulation within the wall behind the heater will reduce heat conduction to the outside too (conservation).

Convection. Heat convection is what you want to happen inside the cookie tins in a controlled way. You control the convection by using multiple cookie boxes, by the placement/use of the fresh air inlet and exhaust air outlet, and by the air connections (pipes) between boxes. Baffles inside the tins might help too.

By using standoffs, that might be about a quarter inch, behind the cookie tins to provide an air gap between the back of the tins and the hardibacker I hope it would create a convection current behind the heater. Then heat from the back of the heater can be conserved (less conduction to the colder outside) with a little more warm/hot cabin air convection movement happening.

Radiation. The cookie tins are meant to safely radiate the heat from the candles to the cabin interior. The more surface of the cookie tins that is exposed to the cabin air the more potential for radiation (up to some optimal point).

Robert had "pipes" between the cookie tins that he "welded" airtight to the tins with JBweld. This morning I wondered what you might use for the pipes. I looked inside my kitchen cupboard at cans of food. The narrowest cans I have are 2.5" wide. Maybe too big? Maybe something smaller like part of a tomato paste can could be about the right size to become part of a pipe between cookie tins.

My thoughts may be (are) a little jumbled. Hope they make some sense and add to the discussion.

[mikeschn]

It seems to me that the hole with the "X" should be eliminated ?

It was! What you see there is a small piece of tin that i slipped in for one of my other tests. It's since been removed!

Mike...

[Esteban]

Robert's original post:

Hi , Im new to this site. I have a 5 by 10 micro camper. Not an official teardrop. I built a heater using 8 hour votive candles for a heat source. outside combustion air is provided with a 2 inch vent in a 2 inch pipe. exaust is 2 inch diameter vent in a 2 inch pipe. no inside air is involved for safety. I light 1 or 2 candles,put on the cover and use a big wing nut to hold cover tight in case something bumps it. the metal box radiates heat all night long.It was tested in 18 degree cold this year and 2 candles plus one body was fine.Even though no inside combustion ail is involved I can still crack both windows and be warm. I tested unit with 6 candles to test for oxygen flame out but never use more than 2. Strips of concrete hardiplank spacers between wood walls and metal box (15 by15 by3 deep) keep wall from getting to hot.

[mikeschn]

By using standoffs, that might be about a quarter inch, behind the cookie tins to provide an air gap between the back of the tins and the hardibacker I hope it would create a convection current behind the heater. Then heat from the back of the heater can be conserved (less conduction to the colder outside) with a little more warm/hot cabin air convection movement happening.

I like the idea of standoffs. Since we are using pipe for the intake and the exhaust, why not use standoffs, and keep more of that radiated heat inside? BTW, I'm not using pipe. I am using something that you might use under your kitchen sink, a thin wall pipe that might be part of a j-trap.

Mike...

[rowerwet]

something like this makes an easy vent/exhaust pipe.

[mikeschn]

I bought a 12" brass tube

http://www.homedepot.com/p/DBHL-1-1-4-i ... oyhq-IS3-A

Mike...

[RandyG]

I'm getting ready to start building a candle heater box, I need a side project. Instead in tins I want to make it from Al and use baffles to seperate the chambers. One thing I am not understanding though, should I run the intake and exhuast vents to outside air or is it Ok to get it from inside if I have other vents in the tear? I wont be camping in the cold often so I want to remove the heater and not have holes in the walls to fill.

[KCStudly]

Better to take it from outside, that way you are not taking from the conditioned air for combustion. Otherwise with the combustion air coming from inside of the cabin, that air would be drawing even more cold air in thru your makeup air vent.