View Full Version : Testing furnace heat exchanger

01-06-2013, 11:13 PM
I need advice on the best way to use a smoke bomb to test for a leak in a furnace heat exchanger. It's a brand new oil burner/forced air , installed in my workshop, and the two certified technicians I've paid big bucks to can't even smell the flue gas odor coming from the fresh air vents. To me, the odor is quite obvious , and I've been using oil burner furnaces ( 3 in all) for 37 years, and I know when the smell is not right. The odor only occurs during the first few seconds after the main blower starts up . After that, the odor disappears, so it would seem that the plenum is filling up with flue gases while the burner is on, but before the main blower comes on. After that point, the pressure is greater in the fresh air plenum than in the heat exchanger. I monitor for CO inside the shop, but don't even detect one ppm CO, so it's not yet a health danger , but the problem could get worse .
My two certified technicians have been a big disapointment. I have the smoke bombs on order , and I'm intent on doing this test , come what may. Instructions on the internet have been incomplete, and/or just nuts. ( And please forgive me. In a moment of temporary insanity, I posted a similar question over on PM.
I'm paying dearly for that mistake, in the form of the usual insults.) I've done most of my own furnace tuning and maintenance over the years, so I'm not entirely new to this. I have all of the necessary instruments to fine tune the furnace, but I've never done the smoke bomb test.