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Once or twice a day...
Once or twice a day my gas furnace makes a loud WHOOSH sound and I can see a small ball of flame form in the chamber. Can you tell me what causes this and how to fix it?
I will try and help, can you tell me brand furnace and is it natural gas or IP gas?
It's a 75,000 BTU RheemImperial 80. Forced air, natural gas.
Your first thought is probably good ones what usually causes this is the heat exchanger, probably has a large horizontal crack in it. You can usually see these with a flashlight looking up into each cell. Many young inexperienced techs will miss this because they are so concerned about cleaning it, they don’t look at the obvious another thing that would cause this is if the burners are not in properly or not lined up properly. My experience says there are horizontal cracks. My professional opinion says to get the company back out and get it fixed and or replace asap.This is a dangerous situation and could cause a fire. Not trying to scare you here, I just want you to take this very seriously. Please have it checked again. The loud whoosh is gas building up and then igniting i.e. small explosions.