I recently dealt with a major oil furnace malfunction. When the proposal quit and I called for repairs, the supplier informed me that the heat exchanger had cracked. The crack was too small for the human eye to detect. I assumed that meant it could be patched and fixed in some way. I was told that heat exchangers cannot be repaired. I then expected that the supplier would simply substitute the broken heat exchanger with a new one, the same way they way they substitute every other part. I was again informed that this wasn’t possible. Apparently a new heat exchanger costs more than a whole new oil furnace. I was forced to tear out the entire heating device and install a new model, then since my oil furnace was less than 6 years old, I hoped that the manufacturer’s warranty would at least cover some of the cost. However, because I’d failed to keep up with regular, annual repair from a licensed professional, the warranty no longer covered the equipment. Plus, the supplier explained that the reason the heat exchanger cracked was because of dust accumulation within the system. If I’d invested in repair every fall, the heating proposal would have continued to operate reliably for many more years. I have now l earned my lesson. I spent a small luck on a brand new, top-of-the-line, high efficiency oil furnace and as soon as it was installed, I signed up for a repair plan. For a small fee, the supplier will come to the house every fall and handle the necessary cleaning, tuning and concernshooting to satisfy the warranty requirements.