My first post...  Many thanks to those who have posted videos and photos.  There are an enormous help!

I'm currently designing a home to be built in central Wisconsin.  I was wondering if you can run the exhaust straight up and through the roof, or if must be run horizontally through a wall.  If it can be run vertically, what stops the exhaust from venting BTUs when the unit is not burning?  I will be gone for days at a time and I'm worried about any extraneous heat loss.  Thanks!

 The GARN can be configured with a vertical flue outlet, which is a special order request.  The installation manual says you can use a T and vertical stack outside the building.

I agree that convection standby loss will be an issue with a long vertical run.  In fact, I think it is an issue with a horizontal flue as well.  I suggest you talk to your dealer and/or Dectra about incorporating a motorized damper in the exhaust flue.  If not in the exhaust flue, perhaps in the intake.

 

 I have noticed on installations using vertical discharge that the stack will induce a small amount of airflow through the Garn even when the combustion blower is off. I first tumbled onto this phenomenon when I drove up to a customers house a few weks after an installation to just check things out. I noticed a thin wisp of smoke, not the typically encountered condensation, emitting from the exhaust stack. I investigated and found that there were a few pieces of wood not completely burned up by the previous cycle still present in the firebox. They were semi actively burning/smoldering due to the small amount of air being pulled into the unit by the stack effect of the chimney. The draft at the loading door was noticeable. That is one of the reasons I usually recommend a horizontal discharge unless circumstances preclude it. 

 What is the guidance for a horizontal exhaust?  Distance from building?  Proximity to doors/windows?  How long of a horizontal run is acceptable?

Thanks,

Bob

I spoke to Jim from Garn last week.  You can vent the exhaust vertically through a roof and you can have 2 - 30 degree bends.  You may not put a cap on a vertical exhaust.  I also asked about the barrel used under a side vented exhaust and what should one do in a vertical situation.  It is only an ash catcher (no embers should be present after the 60' run through the Garn) and nothing is needed in a vertical situation.

Don't know if you've made the exhaust decision yet but I remember a post, either here or at Hearth.com where someone else had a similar concern as he was noticing a 1 degree heat loss with a verticle config. After some other posts, he posted that an experiment with the top of the exhaust covered the same heat loss was detected. I'm sure others here might know better than I but seems like same heat loss with either exhaust config. 

 Steve,

This may be the link to the discussion (GARN standby loss) over at Hearth.com you refer to:  http://www.hearth.com/econtent/index.php/forums/viewthread/35862/