Make up on externally vented furnace?

[twitt (Thomas Witt, CMI MD. Lic. # 30933)]

Hi all,

Quick question - If you have a high efficiency gas furnace with direct pvc vents to the exterior does the unit need any additional make up air from the room its located in?

[wwilson3 (Wayne Wilson, TN 439)]

Need more information Thomas, was it single wall PVC, some have intake air also. how big was the room ? and was it sealed.

[cevans (Chuck Evans, CMI)]

@twitt

Hi all,

Quick question - If you have a high efficiency gas furnace with direct pvc vents to the exterior does the unit need any additional make up air from the room its located in?

Not if it’s obtaining its combustion air from the exterior.

[twitt (Thomas Witt, CMI MD. Lic. # 30933)]

@wwilson3

Need more information Thomas, was it single wall PVC, some have intake air also. how big was the room ? and was it sealed.

Yes, single wall pvc, the unit was placed in a small space under the stairs with no vents in the wall. It was not a sealed unit.

[mlarson (Michael Larson, WI Lic. # 1672-106)]

Is the water heater gas?

[twitt (Thomas Witt, CMI MD. Lic. # 30933)]

@mlarson

Is the water heater gas?

The water heater was electric and located in another part of the house, so we don’t have to take that into consideration.

[cbottger (Charley L. Bottger)]

@twitt

Hi all,

Quick question - If you have a high efficiency gas furnace with direct pvc vents to the exterior does the unit need any additional make up air from the room its located in?

Based on this information the answer would be no

[wwilson3 (Wayne Wilson, TN 439)]

I agree with charlie

[twitt (Thomas Witt, CMI MD. Lic. # 30933)]

Thanks Guys for the help, that was what I assumed but wasn’t sure!