Last week, I was called over to Mr. Morgan Denneny’s home for his annual gas furnace clean-ing. He was telling me how he gets his furnace cleaned religiously every year to make sure that it doesn’t brake down. An older gentleman with a ten year old furnace. He decided this year to change company for various reasons, namely not satisfied with the previous one.

So I proceed to cleaning his furnace and remove the blower assembly. That’s the unit that contains the fan and motor. The purpose of the blower is to send the air over the hot parts called the primary and secondary heat exchangers to cool them down. The flow of the air over the exchangers prevents them from overheating and cracking. Any cracks would send dangerous gases that are flowing through them such as carbon monoxide and carbon dioxide throughout your home. This happens to be the warm air that comes out of your floor registers. He tells me that not one person has ever removed the blower assembly in the ten years he’s had his furnace. Not once to clean it.
Mr. Denneny can’t understand why I was removing it since he changes his filters like clockwork every month or so. You should have seen how big his eyes were when he watched his laundry tube turn black from the grime and dirt accumulated over the years. It was coming off in chunks.

I then proceeded to check the secondary heat exchanger where I found it over half blocked with that same grime and dirt. He couldn’t believe it. He changed his filters reli-giously. A secondary heat exchanger looks a lot like a car radiator. Both heat exchangers must have proper air flow to not overheat and give you the manufacturer’s stated effi-ciency rating. Manufacturers calculate the proper air flow necessary to prevent the metal from over expanding. If insufficient air is flowing the metal over expands. Done often enough it will crack. It would be similar to taking a piece of sheet metal and bending it back and forth, it will quickly crack and brake. Manufacturers are constantly making there heat exchangers thinner to get greater effi-ciencies, making proper air flow extremely important. A special cleaner had to be used three times to get Mr. Den-neny’s secondary heat exchanger cleaned to allow proper air flow. How efficient is your furnace?