# Any way to run vented NG fireplace on inside wall?



## pcampbell (Dec 27, 2008)

Is there such a thing for this application.  We'd like to do a NG fireplace with mantle on an inside wall.  The only way we could exhaust would be either boxing something out the side, which would look very tacky, or going up, preferably inside the studs.  Everything I see that goes "up" is very large.  10" diameter, would require this to either be visible or boxed in.  I know Rinnai makes a zero clearance fireplace that would fit inside the walls of a 2x4, but they do not want you to go vertically, only horizontally, and max. exhaust length of 7'.  What, if any, options does one have for this situation?

P.S. Non vented not an option in my house!


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## pcampbell (Dec 27, 2008)

I came across the Mantis again (someone from this forum pointed this out to me as the most efficient gas fireplace).  -this has a 3" PVC pipe, so you could go between the 2x4 studs.  

I am specifically looking for something so that I can run the exhaust vertically through the wall cavity, so it would not be seen at all...


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## DAKSY (Dec 27, 2008)

If you're gonna install a unit that requires DV pipe for the vent, you're gonna end up with around a 10" structure to conceal it... 
You either conceal it in the room you're installing it in, or you cOnceal it in the room behind the fireplace.
The pipe is 6-5/8 O.D. You need 1" of clearance on all sides in a vertical installation...
Now you're at 8-5/8 before you add the drywall.. 
1/2" on a side there - so you're at 9-5/8...
You may get away with 3/8" drywall, but that'll only save you another 1/4"


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## pcampbell (Dec 28, 2008)

Are you sure about that?

Did you check on the Empire Mantis ?  From what I can tell their exhaust is 1.5" PVC with 0" clearance to combustibles... I have not had time to thoroughly read through the manual enough to determine if/how that would work...

http://dev.obatadesign.com/clients/Empire/pdf2008/manuals/PV28SV50B-2H-NP-1-PV28SV55-CG-2H-NP-1.pdf


There are 2 options, single flue and colinear direct vent.  I guess that the single flue pulls room air for combustion - Not something I would really want.


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## jtp10181 (Dec 28, 2008)

IMO that mantis thing is the ugliest modern fireplace I have ever seen. Personally I would not even consider it.


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## fueldude (Jan 13, 2009)

Give the Mantis a couple of months. They are coming out with a redesigned look in the spring after HPBA Show.

-Fueldude


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## tubbster (Jan 14, 2009)

The problem I have with the mantis is the same problem I had with an un vented unit. Water. Then wet windows and mold.


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## pcampbell (Jan 14, 2009)

Are you saying this from experience or assuming?  I do not think its the same amount of moisture going into the home from 92% furnace and non vented...

We will keep an eye on the new Mantis stuff. I would love to create a built in fireplace type feel with mantle and bookshelves on either side.  More so than just the pipe going through the ceiling is we have very little room to deal with, the 0 clearance and 3" we'll gain by recessing it into the wall is what could possibly make it work.


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## david Lee (Jan 14, 2009)

Most of the major fireplace manufactures like lennox and heatilator manufacture B-vented fireplaces for new construction in warm weather climates. B-Vent is available in round and oval 4" and 5" sizes. For sure the 4" and maybe the 5" oval pipe will fit in between your wall studs. You can pick up B-vented flue at any DIY outlet. Just be aware that B- vented fireplaces are decorative, generally have nice flames, but should not be used if heat is your objective.


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## DAKSY (Jan 14, 2009)

Just be aware that B- vented fireplaces are decorative, generally have nice flames, but should not be used if heat is your objective.

I hafta disagree with that. I have some (limited, I'll admit) experience servicing B-vent units, & other than taking combustion air from inside the structure & having some extra safety spill switches wired in, they're rated along with the DV units,  as heaters...
VC Stardance comes to mind & Jotul makes a B-vent version of a couple of their DV gas stoves... 
MOF the B-vent units have a higher AFUE rating than the DV units...


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## david Lee (Jan 15, 2009)

The orginal poster said he wanted a "fireplace" not a stove. Most factory built B-Vented fireplaces are rated as decorative appliances under Anzi Z21.50 vs. heater rated fireplaces which are tested under Anzi Z21.88. I say most because there could be some exceptions out there.


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## DAKSY (Jan 15, 2009)

Macey said:
			
		

> The orginal poster said he wanted a "fireplace" not a stove. Most factory built B-Vented fireplaces are rated as decorative appliances under Anzi Z21.50 vs. heater rated fireplaces which are tested under Anzi Z21.88. I say most because there could be some exceptions out there.



Not quite. B-vent appliances - STOVES OR FIREPLACES - are ALSO listed under ANSI-Z21.88 -IF they are AFUE or heater-rated appliances...
ANSI-Z21.50 actually applies to natural draft fireplaces that are decorative - i.e. Vented gas logs..No required efficiency rating = no heat
Can you use a thermostat with a B-vent fireplace? Yes, you can, just like with a B-vent stove...
According to ANSI-Z21.50 YOU CANNOT use a thermostat with a gas log set WITHOUT violating that code.


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## pcampbell (Jan 15, 2009)

You can't fit 4" between a 2x4.  2x4 is not 4" deep.  Also B vents do not have 0" clearance to combustibles.


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