# If you do not use the blower....



## tubbster (Nov 16, 2008)

Are you throwing money out the exhaust pipe? I.E., will the exhaust temp be higher when not using the noise maker on a gas stove where said noise maker was an add-on option?


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## R&D Guy (Nov 17, 2008)

Yup!  Without the blower running the unit is going to be less efficient.  How much less efficient is unit specific, but a good ball park range would be 10 to 25%.  Again it really depends on the design of the unit.  Some don't need much help getting the heat into the room, some do and some have a heat exchanger for the blower, while other units just blow a little air up the back and call it good.

So how much it matters really depends on the design of the unit and how well the convection chamber was designed, but any unit I have tested or designed is much more efficient with a blower.


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## tubbster (Nov 17, 2008)

Just as I thought, thanks. This stove is the "shoot a breeze up the back" type. I noticed hearthstone had an actual finned heat exchanger on theirs, at the top, and thought that was cool. (Kinda of been considering doing the same- I have plenty of heat sinks lying around-  bolt one to the top and bottom of the top piece but in light of my other problem, that thought is attenuated a smidge)


How about fuel burn rates: More efficient with the flame set to low? Just trying to get the best output per therm~!


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## Inside Guy (Nov 19, 2008)

I agree with R&D;Guy, for the most part.  It would have to be a very sophisticated air exchange system for a "add on" blower to reduce flue temps.   It doesn't hurt to add a blower, they do help distribute heat, reduce surface & wall temps, etc.  However,  in terms of increasing the efficiency rating (AFUE) of the fireplace, adding a blower does very little to reduce exhaust flue temps.


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## tubbster (Nov 19, 2008)

Inside Guy said:
			
		

> I agree with R&D;Guy, for the most part.  It would have to be a very sophisticated air exchange system for a "add on" blower to reduce flue temps.   It doesn't hurt to add a blower, they do help distribute heat, reduce surface & wall temps, etc.  However,  in terms of increasing the efficiency rating (AFUE) of the fireplace, adding a blower does very little to reduce exhaust flue temps.



So actually, you are not agreeing with R&D;at all?  He states a 10 - 25% change in efficiency, which is pretty significant. Anything that would reduce exhaust temps would affect afue. 

I am really surprised how hot the outside coaxial pipe gets, and that is of course the intake air! It is too hot to touch. I have a feeling the AFUE of my stove is *MUCH* less than that stated in the brochure!


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## R&D Guy (Nov 19, 2008)

Inside Guy said:
			
		

> I agree with R&D;Guy, for the most part. It would have to be a very sophisticated air exchange system for a "add on" blower to reduce flue temps. It doesn't hurt to add a blower, they do help distribute heat, reduce surface & wall temps, etc. However, in terms of increasing the efficiency rating (AFUE) of the fireplace, adding a blower does very little to reduce exhaust flue temps.



I may be missing your point, but if you are increasing the amount of heat exchanged into the room at the same input of BTU's, then by the laws of thermodynamics you would be increasing your efficiency resulting in a lower flue temperature (less heat loss out the flue). Everything has to add up to 100%. 

tubs - the AFUE & Steady State ratings are not policed by any agency, or required to be witness by a independent lab. As I've joked before, the test is likely run by a drunken sailor and a salesman.

If the appliance is also listed in Canada, then it must go through a Canadian efficiency test which has to be witnessed by an independent lab. These tests are not perfect either - for example, you are not permitted to use a blower during these test, but like I said unlike AFUE and Steady State, this test must be witnessed by an independent lab and are therefore more likely to be accurate.

http://www.oee.nrcan.gc.ca/equipment/english/fireplace-results.cfm?PrintView=N&Text=N&last_row=1&sr=1

I don't see your GDS25, but the GDS28 is listed at 57.4% efficient. I don't know how close the 2 are in design, but look on Napoleon's website and note that they claim the GDS25 is a whopping 86% efficient. LMAO! Drunken sailors, and salesmen I tell ya.



http://napoleonfireplaces.com/Stoves/stovesas/gds28.html


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## tubbster (Nov 19, 2008)

WOW!

Those numbers look much more realistic, given the amount of heat I see going right out the pipe.

I like the stove and all, but how hard would it be to make one much more efficient? It's almost 2009!


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## Inside Guy (Nov 20, 2008)

tubbster said:
			
		

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First, I just love talking fireplaces; I was so pumped to find this forum!  

Anyways, I think you're right, I am disagreeing with R&D;Guy  On your standard 36 DV unit, a blower doesn't do much, that is in terms of reducing flue temps.  Now, there are so many made-up marketing efficiency numbers out there it's hard to keep track of them all.  As we all know, AFUE can be manipulated to the best case vent configuration to get the best number.  Yes, P4 is much more strict than AFUE, but even that data can be manipulated.

Anyways, here's my point: with a blower "on" more of the available heat (energy) is distributed into the room, with a blower "off"  that same amount of heat(energy) is distributed more around the fireplace, the walls, mantels, hearth, stone, etc.   As the second law of thermodynamic states, there's no such thing as free energy.  If you're not reducing flue temps, your not reducing heat loss through the exhaust.


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## Inside Guy (Nov 20, 2008)

R&D;Guy said:
			
		

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86%?!?!  That's the problem with all these bogus efficiency claims.  Most consumers don't know the difference in Steady, Thermal, AFUE, and P4... they buy the fireplace with the biggest numbers.  I'm glad a lot of manufactures are pushed to list P4.


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## tubbster (Nov 20, 2008)

So two questions then:

The energuide number - is this a drunken sailor derived number also? IIRC, this stove came in at 64% (yuck).

Would one get better numbers running at minimum throttle?




EDIT: I see the energuide number is what R&D;was referring to. They seem to go from a high of 80 to a low of 51. 64 is right in the middle of the pack.

Sure seems to me a lot of room for improvement.

This one seems to be leader of the pack at 80.
http://www.lexingtonforge.com/ss38dv.htm

It looks fairly conventional!


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## R&D Guy (Nov 20, 2008)

Inside Guy said:
			
		

> First, I just love talking fireplaces; I was so pumped to find this forum!
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> As the second law of thermodynamic states, there's no such thing as free energy.  If you're not reducing flue temps, your not reducing heat loss through the exhaust.



Agreed, I enjoy talking fireplaces on this forum too and hearing peoples ideas, likes and dislikes.  I believe you are referring to the first law of thermodynamics which is _Energy can neither be created or destroyed, it just changes forms_.


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## R&D Guy (Nov 20, 2008)

tubbster said:
			
		

> Would one get better numbers running at minimum throttle?
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> EDIT: I see the energuide number is what R&D;was referring to. They seem to go from a high of 80 to a low of 51. 64 is right in the middle of the pack.
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tubbster - The Canadian efficiency test does test both max and min BTU's.  Why they only list high I don't know, but if you email them you should be able to get the info.

Maybe Inside Guy can talk about his experiences, but off the top of my head I don't think I've seen more than a few degrees of increased efficiency on low.  I don't believe I've ever seen a test where a unit was less efficient on low.


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## Inside Guy (Nov 21, 2008)

R&D;Guy said:
			
		

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Off the top of my head I don't have a good answer either.  I'll dig through a couple project files and find out.


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## R&D Guy (Nov 22, 2008)

I wonder why they don't list the low efficiencies on the Canadian EnerGuide site?


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