When a flame is held under the diverter of my 30-year-old gravity gas furnace, it is blown out by the warm gases rising. Is this normal functioning of the furnace, or is it a hazardous condition meaning the old furnace should be replaced with a new forced air gas furnace? Five technicians have given me both of these answers, 3 of one opinion, 2 of the other. Which is correct? Thanks.

It may not mean that you may need a new furnace at this time but the question is why do you have a restriction in the venting side of your furnace. Is it a restricted vent or dirty heat baffle or negative air pressure in the area of the furnace. We all may need to up grade the SEER of our system but at what cost. I for one need to waite for the money or until I have no option but to replace.

If you hold a match at the edge of the draft diverter and blow it out, does the smoke go into the vent or away from it ? Do this while the furnace is on, if the smoke goes away from the vent then this is a sure indication the vent is not venting properly and should be inspected to determine the cause, good luck, Mike