Is my attic furnace a sealed combustion furnace

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  #1  
Old 01-24-16, 07:41 PM
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Is my attic furnace a sealed combustion furnace

Hello all,

My attic furnace room is not insulated well and there are lots of gaps along the wall. I plan to seal the gaps and install insulation along the walls.

however, I have heard that I can ONLY do this if my attic furnace takes fresh air outdoor. In other words, if my attic furnace takes air from inside the attic, then I should NOT seal the room completely b/c it will cause serious problems.

Question 1>
I have attached detailed pictures to show my attic furnace and would like to know whether my attic furnace is a sealed combustion furnace with a combustion air duct that pulls combustion air from the outdoors.

Question 2> Why the installer drilled a whole in the bottom pipe?
I have seen these holes in two places. Do you guys know why the installer drill a hole in the PVC pipe?

Thank you very much
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  #2  
Old 01-24-16, 08:35 PM
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Yes, you have sealed combustion drawing the combustion air from outside. This is the reason for the two PVC pipes.

I don't know why the installer drilled holes (not wholes) in the pipes. Can you mark your photos showing where these holes are located? The only possible reason I can think of would be to allow for condensate drains and if this were the reason then additional fittings and piping would be required to drain off the condensate to a safe place.
 
  #3  
Old 01-24-16, 08:38 PM
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You have a closed combustion system. One line brings in fresh air and the other line is the exhaust.

Not quite sure how your attic is set up but how can you seal it completely ?
An attic needs to breathe.

I see sheetrock. Is your attic completely sheetrocked ?
What is that round metal duct with the sticker on it in the picture ?

I'm not sure why you have a hole in the line. Did you cover it over ?
 
  #4  
Old 01-24-16, 08:50 PM
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Hello Furd,

So I can seal my furnace room in the attic now. Great news!

I have attached a new picture to show the location of the hole.

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  #5  
Old 01-24-16, 08:55 PM
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Hello PJmax,

My attic furnace is built inside a room in the middle of the attic. The room doesn't have insulation completely on all walls and the door to the furnace room is not sealed at all. I want to insulate the furnace room inside the attic ONLY.

Sorry, I don't know the round metal duct.

The hole is covered now.

Thank you
 
  #6  
Old 01-25-16, 12:44 AM
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What is that round metal duct with the sticker on it in the picture ?
It goes into the return air plenum so I suspect it is either a secondary return or else a fresh air intake, possibly with a motorized damper controlled from a time clock.
 
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Old 01-25-16, 05:22 AM
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The hole in the pipe is probably where somebody actually did their job right by performing a combustion analysis.
 
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Old 01-25-16, 05:34 AM
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Grady, that is a perfect answer. I know when my furnace (an 80% AFUE) was installed I couldn't get those guys to perform a combustion test to save my life. Their answer was that it was set at the factory and didn't need to be tested in the field.

Heck, they wouldn't even check the manifold pressure or clock the gas meter. A year later when I got my "free" (no additional cost) check up I made the tech check the pressure and he found it a bit on the high side. And in case someone thinks it was a "fly by night" outfit, they had been in business about 80 years when I had the furnace replaced. Still in business as I write this.
 
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Old 01-25-16, 01:20 PM
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Furd, I know what you mean about getting installers to do any kind of set up. Heaven forbid they read the installation manual where it says to check gas pressure, flow, temp rise, etc., etc....
 
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