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Can black soot on air filter, in furnace & returns in house be caused by a fixable leak?
I'm homeowner with 22 year old Heil oil burning hot air furnace. My oil company has told me it's from a cracked heat exchanger and that I need a new furnace. Their salesman came out and is working up quotes. He did not look inside furnace. I called second company and their salesman did remove the back panel but could not see a crack in heat exchanger. Should get someone to look closer to find the leak/cause of black soot? That is , could it be from a malfunction that's fixable? It's now AC season and the filter after three weeks is almost pure white.