Author Topic: An inexpensive method of heating a small space.  (Read 17149 times)

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Offline LostViking

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Re: An inexpensive method of heating a small space.
« Reply #50 on: September 01, 2014, 07:00:36 AM »
I have seen and read on this topic before.

I have also read every post in this thread. Wow!

I agree with the OP mostly with the thread derailment, although sometimes they can be both fun and educational. But I will try to stay on topic.

Physics dictate that it is impossible to extract more energy from any given source than it has to offer. For example the amount of BTUs in a gallon of gas is a constant. 114,000 BTUs per Gallon.

The same would go for the amount of BTUs in a tea light. You just simply can not extract more BTUs than any given energy source has to offer.

That being said. Your utilization of that energy can change vastly. Throw a gallon of gas on an open fire and you have about 30 seconds of intense heat and light with the vast majority of the BTUs being lost to the sky.
Another physics constant is heat rises.

The flower pot set up, in effect slows down that exchange to the atmosphere. With a candle and the fact that heat rises, you get very little benefit from the flame other than some light, a by-product of the energy conversion.

The flower pot set up somewhat replicates a triple pass boiler
http://www.google.com/search?q=triple+pass+boiler+vs+standard+diagram&ie=UTF-8&oe=UTF-8&hl=en&client=safari

It gives the heat created by the candle more time in contact the clay surfaces. Heating them before the remaing heat is lost to the atmosphere (your house). Just like that gallon of gas on the fire did not heat up tha atmosphere to any measurable degree, neither will a candle heat up your house. But used more wisely a gallon of gas can provide you with a decent amount of heat outside. And a candle can provide a proportionately smaller but similar effect. 

It does not, nor can it offer up more BTUs then the Tea Light has to offer. it can however utilize those BTUs more efficiently. Trapping the heat and releasing it more slowly into the surrounding area. The clay pots will act as a radiant heat source, a much more efficient source than say convection.

Bederus has been making boilers with the triple pass configuration for may years. They work. American boilers had pins to try and capture as much heat as possible. But much of it was lost out the chimney, like the gas on the fire. The triple pass and the clay pots, both extend the contact time, and surface area of that exchange of heat. Therby transferring more of its energy to its intended target. Not more BTUs, just more efficient use of what's available.

Another thing I do that is somewhat similar, is the following. if I have to have a kero-sun heater running in my house during a power outage. Which can be a frequent occurance where I live. I always put a pot of water on top of it. Water being 240 times more dense than air traps heat and acts as a heat sink. Releasing BTUs long after I have turned off the heater.

Yes, the nordic folks have long been more efficient in their use of BTUs. But we are catching up. Another example of this action. Is wood stoves lined with fire brick. Or as mentioned above, soapstone stoves. They trap heat and release it after the fire has died out.

The pot candle method wil not heat your house. But it will make much more efficient use of the heat generated by a few tea lights and may in fact make you more comfortable if you are close enough to enjoy the benefits of the heat radiated from the clay. Clay itself is pretty good at this. That is why it is so popular for baking. It has a slow and even way of capturing and releasing heat.

I hope that my contribution to this "Train Wreck" helps some. I actually remember when a guy named Levitt, told people he was going to heat houses by burying copper pipe in concrete floors. He got laughed at. But today radiant heat is accepted as the industy standard for effecient heat.

LV,

P.S.
Another factor to consider is the heat loss from your house. It is based upon square footage, as well a volume, shape, and R values. A square house will heat more efficiently than a rectangle house of the same square footage. All other things being equal. Because the square house will have less surface area exposed.

Ceiling height and the amount of glass as well as the quality of that glass will have a hugh effect on heat loss. Also areas with prevailing winds can  increase your heat lose in the area of + or - 15%. Passive solar gain should be factored. Many houses today are built with a design criteria of 0 degrees F as the bottom temp.
Personally I prefer -30F or at least minus 20. Based off 0F your house will not be able to maintain temperature as the temps drop below zero.

In floor radiant heat works great. But it becomes pretty much ineffective past the six foot mark. Enter dual zone radiant designs, or a radiant/convection hybrid system. Outdoor temperature sensors adjust boiler water temperatures to compensate for outside ambient temps too.

Design improvements, as well as material advances have changed the HVAC industy greatly. Many solutions exist now that just weren't possible before. It is way more involved than just sticking a boiler or a furnace in your basement and hoping for the best.

This is carying over to wood stoves a s well.


« Last Edit: September 01, 2014, 08:28:06 AM by LostViking »

Offline zammer

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Re: An inexpensive method of heating a small space.
« Reply #51 on: September 01, 2014, 08:50:08 AM »
The pot candle method wil not heat your house. But it will make much more efficient use of the heat generated by a few tea lights and may in fact make you more comfortable if you are close enough to enjoy the benefits of the heat radiated from the clay. Clay itself is pretty good at this. That is why it is so popular for baking. It has a slow and even way of capturing and releasing heat.

The most concise and spot on answer in the whole thread... :cheers:


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Offline wolfy

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Re: An inexpensive method of heating a small space.
« Reply #52 on: September 01, 2014, 10:42:59 AM »
QUOTE:
Another factor to consider is the heat loss from your house. It is based upon square footage, as well a volume, shape, and R values. A square house will heat more efficiently than a rectangle house of the same square footage. All other things being equal. Because the square house will have less surface area exposed.


......and 'round & conical' is even better!   Now, if I could just figure out a way to install a Finnish or Russian stove in my tipi! :doh:
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Offline wsdstan

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Re: An inexpensive method of heating a small space.
« Reply #53 on: September 01, 2014, 12:42:02 PM »
QUOTE:
A square house will heat more efficiently than a rectangle house of the same square footage. All other things being equal. Because the square house will have less surface area exposed.

Given that each is the same square footage and that the walls are the same height above the ground how can the surface area of a square house be smaller than the rectangle?

A rectangle would, if the heat source is dead center in the middle be harder to heat the ends because they are further away but the surface area would seem to be the same.   :shrug:
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Offline LostViking

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Re: An inexpensive method of heating a small space.
« Reply #54 on: September 01, 2014, 01:12:29 PM »
40x40=1600 square ft, running linear total 160 ft X 8' high=1280 square feet of outside surface.

50x32=1600 square ft, running linear total 164 ft X 8' high =1312 (32 square ft more surface area)

That is only at 8' if you go higher or add a second story it gets larger, plus exposed concrete from the basement.

The further you take the rectangle away from square, the worse it gets.
80X20=1600 square ft, running linear total is now 200'  200' X 8' is 1600 square ft of exposed surface.
« Last Edit: September 01, 2014, 01:25:09 PM by LostViking »

Offline LostViking

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Re: An inexpensive method of heating a small space.
« Reply #55 on: September 01, 2014, 01:22:55 PM »
Also as Wolfy pointed out,

Circles are even more efficient than squares.

But then you have to have that whole pie are squared vs pie are round debate.

Offline wsdstan

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Re: An inexpensive method of heating a small space.
« Reply #56 on: September 01, 2014, 01:23:21 PM »
40x40=1600 square ft, running linear total 160 ft X 8' high=1280 square feet of outside surface.

50x32=1600 square ft, running linear total 164 ft X 8' high =1312(32 square ft (more surface area)

That is only at 8' if you go higher or add a second story it gets larger, plus exposed concrete from the basement.

The further you take the rectangle away from square, the worse it gets.
80X20=1600 square ft, running linear total is now 200'  200' X 8' is 1600 square ft of exposed surface.

Excellent answer.  And it makes sense too.  Thanks.

Wolfy, never mind.
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Offline wolfy

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Re: An inexpensive method of heating a small space.
« Reply #57 on: September 01, 2014, 01:39:59 PM »
 :lol:
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Offline Draco

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Re: An inexpensive method of heating a small space.
« Reply #58 on: September 01, 2014, 01:47:32 PM »
The other issue worth looking at is the question of cost.  Is a BTU produced by a candle actually less expensive than a BTU produced by natural gas? 

Offline wsdstan

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Re: An inexpensive method of heating a small space.
« Reply #59 on: September 01, 2014, 02:10:12 PM »
If both houses are 1600 square feet then they each contain 12,800 cubic feet of air if they have 8'sidewalls.  As I mentioned in my original post a rectangle would be somewhat harder to heat as its ends are further away from a heat source placed in the middle but you are heating the same cubic feet of air.

I was not grasping surface area correctly but it seemed, offhand, that it ought to be the same.  I see that it isn't but that doesn't change the fact that you are heating the same volume of air.

 
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Offline LostViking

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Re: An inexpensive method of heating a small space.
« Reply #60 on: September 01, 2014, 02:18:55 PM »
Therein lies the dichotomy.

It will almost always be cheaper to source energy from the grid or main stream sources.
Electric, fuel oil, propane or natural gas, will always present a more attractive cost/BTU than more  independent energy sources. Wood can be a variable, but if you factor in your labor, and equipment costs. Even if you source it from your own land, It's still up there. I appears cheap because labour is not usually factored. I love wood heat by the way.

But the candle/pot typr heater is independent from the grid and will work if it is somehow interupted.
Providing you had the forethought to put by some extra candles.

Generating your own electricity will be more expensive than the grid. But it provides you more independence.

Grid sources may vary in their costs. When I built my first house #2 fuel oil was around $00.72/gallon. Now it is well in excess of $3.00. Electric was $00.13/kw where I live now it is around $00.08/kw. That is artificially low due to government subsdies of wind farms and will expire after the 10 year mark.
Propane used to be cheap here. But that spiked hard last year. Because supply could not keep up with demand.

But I believe any of these will still be cheaper than trying to supply energy from a more independent source.


I am looking for the BTUs in a Tea Light Candle, but they would be approximate at best. 

Offline LostViking

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Re: An inexpensive method of heating a small space.
« Reply #61 on: September 01, 2014, 02:29:54 PM »
If both houses are 1600 square feet then they each contain 12,800 cubic feet of air if they have 8'sidewalls.  As I mentioned in my original post a rectangle would be somewhat harder to heat as its ends are further away from a heat source placed in the middle but you are heating the same cubic feet of air.

I was not grasping surface area correctly but it seemed, offhand, that it ought to be the same.  I see that it isn't but that doesn't change the fact that you are heating the same volume of air.

You are 100% correct, the volume of air inside should be the same. But the heat loss from the added exposed outside surface area will cause you to use more energy to heat it. All other factors being the same.

Also take into consideration that heat rises. . When comparing a rectangle to a square. A flat rectangular ceiling will have pretty much the same exposed surface area as its corresponding square counterpart. Length X Width. But the exposed area of your ceiling/roof will expand in a similar manor as the side walls if you have vaulted ceilings or cathedral celiengs.

Not something to get too hung up on. Glass is your major heat loss and will affect your heating costs far more that being out of square will. There are many other influencers too.

But all things being equal efficiency goes like this,
1. Cylinder, Pi (3.1416) x Radius squared x H
2. Square Cube, LxWxH
3. Rectangular Cube, LxWxH

When you look at it two dimensionally it looks the same. Factor in that third dimension and it begins to make sense.
« Last Edit: September 01, 2014, 02:46:59 PM by LostViking »

Offline LostViking

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Re: An inexpensive method of heating a small space.
« Reply #62 on: September 01, 2014, 03:00:21 PM »
To keep this train from coming too far off the tracks yet again. Here is a link to some actual calculations of using Teal Lights vs other sources of energy,

http://coldhousejournal.com/2013/11/09/impractical-heating-idea/

My biggest concerns would be fire risk from pets or kids and reduced air quality.

But it is still a cool idea and worth playing around with. Think space heater, not furnace. Worth it for the conversation alone.
« Last Edit: September 01, 2014, 03:07:51 PM by LostViking »

Offline Draco

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Re: An inexpensive method of heating a small space.
« Reply #63 on: September 01, 2014, 03:52:54 PM »
Everything I saw put the BTU of a candle flame at 270 to 300.  See the links in my other post. 

Offline Draco

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Re: An inexpensive method of heating a small space.
« Reply #64 on: September 01, 2014, 04:03:14 PM »
To keep this train from coming too far off the tracks yet again. Here is a link to some actual calculations of using Teal Lights vs other sources of energy,

http://coldhousejournal.com/2013/11/09/impractical-heating-idea/

My biggest concerns would be fire risk from pets or kids and reduced air quality.

But it is still a cool idea and worth playing around with. Think space heater, not furnace. Worth it for the conversation alone.

Nice find.  The problem is to match the equivalent of 100 hours of electric space heater (on low) means you have to burn the 500 candles in that same time frame.  So that is not one pot one candle.  That would be 5 candles per hour for the 100 hours.  Not sure how long the candle burns but it may require more going at a time to use all 500 during the 100 hours.   And of course at least in my area during February you would freeze in just about any house trying to heat it with an electric heater on low. 

Offline wsdstan

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Re: An inexpensive method of heating a small space.
« Reply #65 on: September 01, 2014, 04:12:41 PM »
I am going to go turn my thermostat up.  :P
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Offline Quenchcrack

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Re: An inexpensive method of heating a small space.
« Reply #66 on: January 08, 2015, 12:06:45 PM »
If anyone wants to actually run an experiment, Ikea sells tea light candles for about $4 per 100.  They are rated at a 4 hour burn time.  As for the thermodynamics, radiant heat transfer is the most efficient but falls of proportional to the square of the distance from the heat.  It seems that the candle would not put off much "FELT" heat if you were a few feet away.  By transferring the radiant heat to the clay pot, the pot feeds it back by convection through the air.  The warm air moves around and can increase the volume within which the heat can be felt.  That's my story and I'm sticking to it.   :fire2:
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Offline MnSportsman

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Re: An inexpensive method of heating a small space.
« Reply #67 on: January 08, 2015, 09:09:24 PM »
And.... basically... Since no one here actually gives a crap anymore about finding a way to heat a small space. . & doesn't have an open mind about how some folks might do so...It is a "Moot' point".


   Some folks step in sheit, and go  "Dammit! I stepped in some sheit.". Others might think, "Sheit! Where is the damn thing that sheit?"


  They all have Sheit on them, but not a one makes a difference, when it comes down to it.
 ;)


Have a NICE day!
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I love being out in the woods!   I like this quote from Mors Kochanski - "The more you know, the less you carry". I believe in the same creed, & think  "Knowledge & honed skills" are the best things to carry with ya when you're out in the wilds. They're the ultimate "ultralight" gear! ;)

Offline arngmechanic

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Re: An inexpensive method of heating a small space.
« Reply #68 on: February 07, 2015, 08:11:55 PM »
Check out he rocket stove. Very effective. Made one out of two Pepsi cans an cooked an egg with my tiny cast iron skillet.


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