Oval furnace pipe

[boostaholic1]

Installing an older reznor unit in my garage. It has a 6x9 oval vent on the backside. I am thinking that an 8" round piece should oval out to fit. Can anyone confirm this or know where I can find the proper fitting for the exhaust?

Thanks for the help

 

[PWC Repair]

Commonly just referred to as 6" oval pipe. Was more common on the wall furnaces years ago. Check with your local HVAC supply. Maybe even Home Depot or Grainger. You could maybe egg out a 7" pipe.

 

[boostaholic1]

Commonly just referred to as 6" oval pipe. Was more common on the wall furnaces years ago. Check with your local HVAC supply. Maybe even Home Depot or Grainger. You could maybe egg out a 7" pipe.

I have tried 7" and it doesn't flatten out enough to get over the 9" part. Gonna try a piece of 8" today and hopefully that works. I will stop at the commercial place as well and see what they have.
Just trying to save time by not going back and forth like every other plumbing project I do!! Haha

 

[metlmunchr]

Measure the circumference and divide by 3.14 to find the corresponding round size that would flatten to the 6x9 oval.

Be aware that most round duct is made from 28 or 30 gauge material in the smaller sizes while true furnace pipe is normally 24 ga. Don't substitute the thin stuff as it will burn out in short order and create a dangerous situation. 24 ga pipe in an 8" diameter is amazingly stiff, so you may have to actually track down a factory made oval to round transition.

 

[boostaholic1]

Measure the circumference and divide by 3.14 to find the corresponding round size that would flatten to the 6x9 oval.

Be aware that most round duct is made from 28 or 30 gauge material in the smaller sizes while true furnace pipe is normally 24 ga. Don't substitute the thin stuff as it will burn out in short order and create a dangerous situation. 24 ga pipe in an 8" diameter is amazingly stiff, so you may have to actually track down a factory made oval to round transition.

Depending on how stiff and strong it is, I was planning on putting it in the press to flatten it out a little at a time. I am concerned with the seam splitting though.

 

[Lassen Forge]

Commonly just referred to as 6" oval pipe. Was more common on the wall furnaces years ago. Check with your local HVAC supply. Maybe even Home Depot or Grainger.

This. I have a couple wood stoves that have 6" oval outlets, IIRC I got the adapters to go to 8" round flue at a local stove shop, they drop in and fit.