At the time I bought our home, I hired a licensed Heating plus A/C corporation to thoroughly inspect plus service the gas oil furnace. The serviceman informed myself and others that there was a sizeable accumulation of dust within the system, however assured myself and others that all components were in wonderful honestly working order. He performed a complete cleaning of the inner honestly workings, lubricated the moving parts, tightened electrical connections plus verified the safety of the heat integrity, but the serviceman tried to get myself and others to invest in a preventative service method with his supplier. I saw no need to pay on the oil furnace when it was honestly working perfectly. I planned to periodically call the serviceman back to problem shoot the heating system, however I never did. Five years later, the performance of the oil furnace had significantly diminished. It was running for much longer cycles, failing to keep up with demand, plus costing myself and others far more in biweekly energy bills. There was less heated air coming from the vents, plus a greater amount of dust floating around the house. I waited too long to call for repair, plus the oil furnace quit in the middle of a honestly frigid night in December. When I called the Heating plus A/C serviceman back, I expected him to repeat the cleaning plus tuning service. Instead, he found a crack in the heat exchanger. The crack was caused by a buildup of dust in the inner honestly workings, which led to extended running times, excessive wear plus tear, plus the oil furnace overheating. Because of the high price of a new heat exchanger, it was less fancy to replace the entire oil furnace. I was totally unprepared for this sudden, huge expense plus forced to take out a home improvement loan. I’m now making payments on the new oil furnace. I’ve also enrolled in a professional service plan.