Mount Best

There's a lot more than the lovely chest fridge at http://tinyurl.com/cay4t .
The 80% wood stove might be more efficient with a concentric pipe chimney with flue gas traveling up the inner pipe and room air traveling back towards the stove in the space between the inner and outer pipes to make a counterflow air-air heat exchanger with condensation, which might add about 15% to woodstove efficiency and reduce air pollution and allow burning wood with a higher moisture content with no efficiency penalty (or maybe a gain :-) We might pressurize the stove air inlet slightly with a small fan to assure adequate draft (given the cooler chimney) and to regulate the heat output, and use a CO detector in case the inner pipe develops a leak and the room air fan fails.
A heat pump with a 4-6 COP is nice, but a good solar heating system might have a COP of 50 or more. John Christopher's CSI building in cold, cloudy New Hampshire is heated with "98% solar power and 2% fan power." PE Norman Saunders calculates that some of his solar houses will only need "purchased heat" for a few hours every 35 years. No wood. No heat pumps.
The reflective solar heating system might lose lots of heat through windows at night and on cloudy days. A low-thermal mass sunspace with an insulated wall between the sunspace and the living space and warm air circulating between the two and no airflow at night might be a lot more efficient. The Barra system stores heat from sunspace hot air in ceiling thermal mass, with little heat loss at night. A slow ceiling fan and thermostat might bring warm air down from a low-e ceiling when a room is occupied.
As an alternative to a massy ceiling. Fin-tube pipes near the ceiling could both collect and distribute heat from a stratified storage tank, with the help of a ceiling fan. The tank might also have a $60 1"x300' pressurized PE pipe spiral near the top to make hot water for showers.
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

a tri-axial pipe? are you advising people to fabricate their own, or you know a source?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
no_child_left snipped-for-privacy@yahoo.com.sg wrote:

Is it so difficult to fabricate such a thing? Take two single-walled flue pipes of different enough diameters and place one inside the other. Space them apart using bent pieces of metal or spring clips made from coat hangers or the like.
Anthony
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

that's a co-axial pipe. A dozen commercial products use it. Flue gases flow out, exchanging heat with combustion air.
Nick sounded as if (sometimes he posts without proofreading, I can show you some posts where he confuses the dimensions of thermal conductivity and thermal conductance) he was proposing a THIRD airflow that would bring vent air into the living space.... a pipe inside a pipe, inside a third pipe.
And yes, George, it's not a "new" idea. He didn't claim it was. By the way, what's YOUR track record vis-a-vis optimizing thermal designs? If you post half the tutorial material I've learned from Nick, I'll sing your praises too.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Some gas appliances and pellet stoves work that way.

Interesting. I don't recall those mistakes. I archive most of my postings at http://www.ece.villanova.edu/~nick . If you send me a list, I'll fix 'em.

No... just 2 pipes, with room air vs outside air flowing back to the stove in the space between them.

It may be new, but it seems obvious to someone "skilled in the art."

George says he's an expert. Let's try an extremely simple test. If 10 cfm of 70 F combustion air warms to 800 F before it exits a woodstove to enter a perfect conterflow heat exchanger and 560 cfm of 70 F room air enters the other end, what's the temperature of the room air at the other end of the heat exchanger?
Anyone can answer, but it would be fun to let George give it a try first.
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ece.villanova.edu wrote:

fact that he is "skilled in the art"

Where did I claim to be an expert, Nick. I asked you some very simple, practical questions,
Remember this part;
Tell us Nick, What is the wall thickness of these pipes?
How much do they weigh?
How do you propose to support this weight?
With the forced air feed to the stove, how hot will the stove end of the inner pipe get?
How hot can it get before it starts to slump under it's own weight?
Anyone can answer, but it would be fun to let Nick give it a try first.
You can see how Nick works. He just doesn't answer the questions.
All the theory in the world is not worth a pair of fetid dingos kidneys if it is not practicable.
Now, I could go to the trouble of changing Nicks units to SI units, Dig out the relevant books and answer Nicks question. Might even get it right. Nah, it would be a pointless exercise.
The question is this: Is Nicks little day dream practicable.
Come on Nick. Is it practicable? Have you done this? Does it really work?
I'll give you a hint. It does work. It was as noisy as all get out. When the contra flow fan was not running it was cooking in the heat rising up from the stove.
In the end the simple solution was a nice quiet fan near the ceiling to de-stratify the air in the room.
Had I done the maths, the result would have been the same. Not worth the trouble.
Not a new idea. As obvious as all hell. I have the skill to build it.
Would I do it again? NO.
I opted for a Masonry Contra flow stove for heating. And no motors.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
George Ghio wrote:

"I took one stab at it, it didn't work out perfectly, so I gave up. I don't have persistence enough to be bothered. I went and bought a commerically-available product"
The unwashed masses do draw a conclusion at whatever point they got too tired to think anymore.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'd put a 6"x15' pipe inside an 8" pipe, with the 6" pipe passing through an 8" T near the end and a 10" 560 cfm fan in a 10" to 8" reducer plugged into the arm of the T. Room air would flow towards the stove in the space between the two pipes and exit near the stove.
The stove might have a small muffin fan attached to the door, running at a low speed (to provide 5 cfm of draft air?) with a room temp thermostat to increase that speed if more heat is needed.
We might make a condensing chimney with a lot more plain pipe inside a house and a taller chimney or partially-open stove door to account for the reduced bouyant force from the cooler chimney.
And use a CO detector, in either case.
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ece.villanova.edu wrote:

This is some of the best comedy you will ever see.
If one motor is good then two must be better.
Tell us Nick, What is the wall thickness of these pipes?
How much do they weigh?
How do you propose to support this weight?
With the forced air feed to the stove, how hot will the stove end of the inner pipe get?
How hot can it get before it starts to slump under it's own weight?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@ece.villanova.edu wrote:

You gotta laugh.
Anyone interested in stove and heater design would be wise to visit "The Maine Wood Heat Company"
They "WILL" be able to help you while Nick "MIGHT" actually do "SOMETHING" "IF" he "SOMEHOW" decides to stop pissing in the wind.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Nick's job is not distributing existing products. Retarded children could do that.
Nor even to actually physically produce working prototypes of his ideas. Average engineering students could do that.
Nick's job is seeing what's NOT there... hearing the dog which DIDN'T bark.
Nick stands out like a sore thumb, because most of the people with Nick's insights, choose to copyright them, or even hold them as trade secrets. So count your lucky stars that you have access to them for free.
If you feel they have no value.... no one can force a horse to drink.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
no_child_left snipped-for-privacy@yahoo.com.sg wrote:

As far as can be proven here Nick has never produced anything.
If you want to know about heating without the nonsense talk to the Maine Wood Heat Co.
Contra flow wood heating was invented in the 1500s as a result of Europe's first energy crisis.
Nick's post offers nothing new or inventive that has not been done.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.