Stove efficiency calculation

[nortcan]

And how tall is the chimney?

I think it's about 21 Ft. And I like to see how the stove /cats are working /burning clean. I installed a cheap security camera on the roof years ago when having VC Defiant Encore, I was surprised many times when going outside to see smoke at the chimney's end, so I went in home to set the air control, wait a little and go back outside to check and repeat that many times...Cats are good but not so perfect as advertised, The cat probe on my Heritage is not a reliable way to be shure the cats are burning OK even if the probe dial says : **catalyst active**... .

 

[nortcan]

And how tall is the chimney?

21 Ft

 

[Todd]

Isn’t soapstone more of an insulator that will effect heat transfer efficiency? Yes once it’s hot and stays hot it radiates heat pretty well but cold starts or just a single fire per day could send more heat up a chimney? Steel and cast iron should have a much higher heat transfer efficiency and I would think the more radiant the stove the more efficient?

 

[nortcan]

Isn’t soapstone more of an insulator that will effect heat transfer efficiency? Yes once it’s hot and stays hot it radiates heat pretty well but cold starts or just a single fire per day could send more heat up a chimney? Steel and cast iron should have a much higher heat transfer efficiency and I would think the more radiant the stove the more efficient?

I'm talking about steady burnings. When the top of the stove is 400* F during let say one hour : soapstone, cast iron or steel, 400* F still the same steady temperature. Shure when having a new fire, soapstone takes longer to send heat in the place, cast iron less and steel is faster and when they get 400* F on top, my concern is about what is the stack T* at 11 inches from the stove's top. In my mind, more difference between these 2 places is showing the capacity of a stove to send more or less heat in the place and more orless to the outside. As already said most pepoples buy a wood stove to keep the heat inside and warm up the place and the efficiency advertised doesn't reflect that, the custommers dont know how it works and many dealers/sale men dont know how it works anymore. It would be easy for the stove testers /agencies to make the top and stack tests when doing the other tests and that would give a real and simple image of each different stoves performances.

 

[Todd]

If you look at the EPA test results for different stoves you can see what the test run temps were for low, Med, and high burn rates, both stove top temps and flue temps.

I agree there could be a better more real world explanation of stove efficiency for consumers but how would that be done with so many different variables in wood burning?

 

[nortcan]

If you look at the EPA test results for different stoves you can see what the test run temps were for low, Med, and high burn rates, both stove top temps and flue temps.

I agree there could be a better more real world explanation of stove efficiency for consumers but how would that be done with so many different variables in wood burning?

Hum, can you tell me where I could see what you said about EPA tests for temp. on top of the stove and flue temp ? Thanks

 

[Todd]

EPA Reports - HearthstoneTech

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hearthstonetech.com

Here’s Hearthstones EPA reports.

 

[bholler]

I'm talking about steady burnings. When the top of the stove is 400* F during let say one hour : soapstone, cast iron or steel, 400* F still the same steady temperature. Shure when having a new fire, soapstone takes longer to send heat in the place, cast iron less and steel is faster and when they get 400* F on top, my concern is about what is the stack T* at 11 inches from the stove's top. In my mind, more difference between these 2 places is showing the capacity of a stove to send more or less heat in the place and more orless to the outside. As already said most pepoples buy a wood stove to keep the heat inside and warm up the place and the efficiency advertised doesn't reflect that, the custommers dont know how it works and many dealers/sale men dont know how it works anymore. It would be easy for the stove testers /agencies to make the top and stack tests when doing the other tests and that would give a real and simple image of each different stoves performances.

400 on any of the cast or steel stoves I have had would be way to low for a steady cruising temp and my pipe surface temps would be 250 to 300.

 

[nortcan]

400 on any of the cast or steel stoves I have had would be way to low for a steady cruising temp and my pipe surface temps would be 250 to 300.

1* -Why, easy to keep 400*F with cats engaged. ? 2*- So you get 400*F heat for the room and 250/300 outside of the house ? You may find that good but not me !

 

[bholler]

1* -Why, easy to keep 400*F with cats engaged. ? 2*- So you get 400*F heat for the room and 250/300 outside of the house ? You may find that good but not me !

Measure the temp at the top where the exhaust actually goes outside. And I have only run one cat stove but areas of the top near the cats will be way over 400 even on low. You also have to factor in the btus going out vs the btus co.ing off the stove. If the whole stove is 400 that's allot of surface area radiating heat

 

[nortcan]

Measure the temp at the top where the exhaust actually goes outside. And I have only run one cat stove but areas of the top near the cats will be way over 400 even on low. You also have to factor in the btus going out vs the btus co.ing off the stove. If the whole stove is 400 that's allot of surface area radiating heat

When I say 400*F on top of the stove, it's on the rear side of the top of the stove, so above the left cat in the stove , where the catalyst probe is in the stove. I will check the stack temp. at the ceiling as you said. But in some installations, the stove's outlet goes horizontal to the outside of the house as does the heat ...An other raison to have longer gases flue path inside the stove to try to keep a little more heat inside the house or some kind of heat exchanger inside of the stove.

 

[bholler]

When I say 400*F on top of the stove, it's on the rear side of the top of the stove, so above the left cat in the stove , where the catalyst probe is in the stove. I will check the stack temp. at the ceiling as you said. But in some installations, the stove's outlet goes horizontal to the outside of the house as does the heat ...An other raison to have longer gases flue path inside the stove to try to keep a little more heat inside the house or some kind of heat exchanger inside of the stove.

There is a reason I have always had steel or iron stoves. If it's 400 over the cat while the cat is active I would say yes your sending allot out the chimney.

 

[nortcan]

There is a reason I have always had steel or iron stoves. If it's 400 over the cat while the cat is active I would say yes your sending allot out the chimney.

I think there are some steel or cast iron stoves sending the heat to the place slowly a little like ths soapstone does, not shure but I think they have a sort of jacket around the stove. We like the fact to get heat slowly with soapstone but : cat is a lot of maintenance : the cats must be cleaned many times during a season... I'm on an other wood stove forum and a lot of peoples hate to have to clean the cat, many peoples are handy and a lot are not. I made some searches on wood stoves and see some stoves burning very clean without cat, so less bothering.

 

[bholler]

I think there are some steel or cast iron stoves sending the heat to the place slowly a little like ths soapstone does, not shure but I think they have a sort of jacket around the stove. We like the fact to get heat slowly with soapstone but : cat is a lot of maintenance : the cats must be cleaned many times during a season... I'm on an other wood stove forum and a lot of peoples hate to have to clean the cat, many peoples are handy and a lot are not. I made some searches on wood stoves and see some stoves burning very clean without cat, so less bothering.

Well yes and no. Jacketed stoves soften the heat by taking the intense radiant heat off the steel and changing much of it into convective heat.

And a well designed cat stove with proper draft shouldn't need anything done with the cat all season.

Yes there are still plenty of good noncats as well. And yes the good ones take less maintenance and less money in parts than cat stoves. But you loose some of the low end burning capability

 

[nortcan]

If you look at the EPA test results for different stoves you can see what the test run temps were for low, Med, and high burn rates, both stove top temps and flue temps.

I agree there could be a better more real world explanation of stove efficiency for consumers but how would that be done with so many different variables in wood burning?

I called to the lab. Polytests who made the Heritage 8024 in St-Jean-sur-Richelieu, Qc . The guy told me they don't make the top of the stove temp. and the stack temperature comparison. I read the test report you suggested to me and there is no comparison for both temp. But I also learned a lot of details about the emission rate, what is advertised from the company is an average weight fron many tests. So the emissions from the stove in real life can vary according to a lot of elements.

 

[bholler]

I called to the lab. Polytests who made the Heritage 8024 in St-Jean-sur-Richelieu, Qc . The guy told me they don't make the top of the stove temp. and the stack temperature comparison. I read the test report you suggested to me and there is no comparison for both temp. But I also learned a lot of details about the emission rate, what is advertised from the company is an average weight fron many tests. So the emissions from the stove in real life can vary according to a lot of elements.

Yes of course real world results are very different from lab testing. We all know that. They don't fully load the stove they use fans so the draft is consistent etc. But they do that because they need to remove as many uncontrolled variables as possible so testing is consistent

 

[stoveliker]

One thing: comparing temperatures (stove top and surface of the flue) is not in any way indicative of relative heat flows from stove to room and they the chimney up and out.
You're comparing apples and oranges.

Efficiency is defined as the ratio of heat flows. NOT some measured temperatures. Heat flow is something very different as temperature. (One has units of temperature and the other has units of energy per cross sectional area per second.
It's like comparing the distance driven to the number of cars transiting some point on a road...

 

[nortcan]

One thing: comparing temperatures (stove top and surface of the flue) is not in any way indicative of relative heat flows from stove to room and they the chimney up and out.
You're comparing apples and oranges.

Efficiency is defined as the ratio of heat flows. NOT some measured temperatures. Heat flow is something very different as temperature. (One has units of temperature and the other has units of energy per cross sectional area per second.
It's like comparing the distance driven to the number of cars transiting some point on a road...

HaHAHa, too funny you !

 

[bholler]

HaHAHa, too funny you !

Why do you say that?

 

[nortcan]

Why do you say that?

Because what stoveliker said is like a school complicated theory most peoples don't understand and will never use in the real life : like trygonometry or algebra,it may looks smart but gives not a clear answer. If you check all the answers on the subject here , the answers are different from one to the other, for the common public, it's important the stove companies give simple descriptions on how the product really will heat their house like : in the same conditions like when doing emission tests, they could compare the stove temperature compare to the stack one to see what stay in home and what is send outside of the home, that is what stove buyers want to know. If making a public survey asking : *what is the meaning of a stove efficiency *, what do you really think the answers will be ??? So peoples compare something without knowing what it is.

 

[bholler]

Because what stoveliker said is like a school complicated theory most peoples don't understand and will never use in the real life : like trygonometry or algebra,it may looks smart but gives not a clear answer. If you check all the answers on the subject here , the answers are different from one to the other, for the common public, it's important the stove companies give simple descriptions on how the product really will heat their house like : in the same conditions like when doing emission tests, they could compare the stove temperature compare to the stack one to see what stay in home and what is send outside of the home, that is what stove buyers want to know. If making a public survey asking : *what is the meaning of a stove efficiency *, what do you really think the answers will be ??? So peoples compare something without knowing what it is.

Uhhh his answer is absolutely correct. Everyone has been giving the simple answer but the actual measurements and calculations are very complex.

And I use algebra all the time trig occasionally. And yes both absolutely give you clear answers.

 

[nortcan]

If you look at the EPA test results for different stoves you can see what the test run temps were for low, Med, and high burn rates, both stove top temps and flue temps.

I agree there could be a better more real world explanation of stove efficiency for consumers but how would that be done with so many different variables in wood burning?

EPA Reports - HearthstoneTech

Your SUPER-powered WP Engine Site

hearthstonetech.com

Here’s Hearthstones EPA reports.

I read it, called the lab, no comparison between temp. on top of the stove and temp on the stove pipe.

 

[stoveliker]

I read it, called the lab, no comparison between temp. on top of the stove and temp on the stove pipe.

Exactly. See above for why that is...
A 2" ministove at 2000 F, won't heat your home despite being hot.

 

[nortcan]

Exactly. See above for why that is...
A 2" ministove at 2000 F, won't heat your home despite being hot.

At 2000*F the little stove will disappear...lol. In fact, what I wanted to do was to see if many peoples exactly knew/understand the real meaning of the term : EFFICIENCY in the real world or in the house ! I never wanted to frustrate someone on the forum here.

 

[stovexxx]

the first thing is to try to optimize the functioning of the stove in possession, actually understand which setting and draft allows for greater performance, the yield, I think that's the right term to use, for me efficiency means more the heat produced in proportion to the wood inside, without considering the quantity that is transferred to the house, yield also considers the heat transferred