When winter hits, having a clean and efficient heater not only makes the house more comfortable, but also helps prevent plumbing problems. Having the heater cleaned and checked every year should be a part of good home maintenance.
One thing the air conditioning service technician needs to look for are cracks in the heat exchange. These cracks are not just cosmetic flaws that develop over time. Cracks can be very dangerous as they let carbon monoxide into the home. Carbon monoxide poisoning can lead to sickness or death.
There is another danger that may result from cracked heat exchangers. That is fire. The crack may grow over time, thus allowing the furnace flame to reach the area where the electrical controls are. This can start a fire.
Why does a heat exchange crack? Is there any way to prevent this? No, like anything mechanical, over time, even the best quality of anything mechanical ages, and that includes the metal itself. Over the course of the lifetime of the furnace, the furnace metal is heating up and expanding and then cooling thousands of times. Like any metal, if you continually work it back and forth, over time it weakens.
There are many techniques that have been developed to discover cracks in the heat exchange. Some are more effective than others and you need to talk to your HVAC repair man to find out what system he uses to detect cracks. Visual is the best, but there are others. It can take an hour or more to find a defect in a heat exchanger, so not every technician or heating company looks for it. They can be difficult to find because there is not one “normal” way the cracks operate.
For example, if you have a combination heater/air conditioning unit, and you do not turn the pilot off in the summer, what can happen is that the cooler moist summer air passing over the hot heat exchanger can cause condensation on the heat exchanger. This can lead to rust and compromised metal strength. Holes can develop. This can lead to failed systems due to rust. Newer systems automatically shut the pilot off, but if you have an older system, this is something to consider if whether rusting and corrosion has occurred.
The best thing to do to be safe from the danger of a cracked heat exchange is to plan a yearly servicing of your heating unit, and talk to your HVAC service man about getting this inspection done. It may cost a little more for this service, but considering the consequences of neglect, it is definitely worth it.