HVAC-Talk: Heating, Air & Refrigeration Discussion

There is an exhaust pipe from the furnace that goes up and out of the ceiling. There are 2 holes in the pipe, below where the exhaust pipe connects to the straight pipe that goes up and out of the ceiling. I am wondering what these holes are for. I have a photo but I guess I can

HVAC-Talk: Heating, Air & Refrigeration Discussion

HVAC-Talk: Heating, Air & Refrigeration Discussion

Engineering Tomorrow

HVAC-Talk: Heating, Air & Refrigeration Discussion

Air conditioning - Wikipedia

HVAC-Talk: Heating, Air & Refrigeration Discussion

All HVAC (Heating, Ventilation and Air-Conditioning) News and Press Releases from PR Newswire

HVAC-Talk: Heating, Air & Refrigeration Discussion

HVAC-Talk: Heating, Air & Refrigeration Discussion

HVAC-Talk: Heating, Air & Refrigeration Discussion

HVAC-Talk: Heating, Air & Refrigeration Discussion