We all love and respect well-maintained old homes. Of course, even the loveliest old homes are really Ships of Theseus—the parts within them have been replaced so many times over that in many respects, the house is as “new” as any others. In other words, a house built in 1920 is not running a furnace from 1920. Not only do advances in performance, efficiency, and cleanliness all but dictate periodic replacement of your furnace and air conditioner, the inescapable fact that machinery wears out and fails means that you will eventually have to complete a full overhaul of your HVAC system. Whether you’re taking up residence in a well-established house or you’re the first family to move into a piece of new construction, complete HVAC replacement is inevitable. We realize that the mere thought of shelling out for a brand-new furnace is daunting when there are so many other ongoing expenses; but by learning how to know it’s time to replace your HVAC system, you can anticipate system replacement, budget accordingly, and most importantly, save some money in the process by avoiding some costs along the way.
All Good Things Come To an End
Just as milk and eggs come with an expiration date, so too do your furnace and air conditioner. Fortunately, you’ll have quite a bit more time to enjoy your HVAC system than you will your groceries, but nevertheless, you must remain aware that their lifespans are finite, no matter how well-built and hardy they are. Your air-conditioning unit will probably need to be replaced once every ten years, while you can expect your furnace or boiler to last about 15 years. As you pass these mileposts—which should be printed on the sides of your respective units, and if not, make note of them yourself—you should start to be aware that any problems that arise are most likely indicative of the end of that unit’s useful life. But just because all furnaces and AC units are destined to be replaced, don’t take that as an excuse for poor stewardship during the units’ lifespans. Annual maintenance checks, conscientious usage patterns, and regular filter changes won’t double or triple the natural lifespan of a furnace; they will, however, keep your repair costs low and prevent your unit from lasting much less than 15 years.
Dust in the Wind
Whether you opt for traditional fiberglass filters, pleated furnace filters, or washable filters, this unassuming but integral furnace accessory is responsible for capturing the dust in your home and keeping it from circulating through your ducts or compromising the performance of your furnace. Nevertheless, you may notice that despite your best efforts to remember the filter and keep your furnace running at peak performance, there’s still an awful lot of dust turning up throughout your home. In the winter, this could be the result of leaks in your ductwork, allowing accumulated dust from your attic and basement to infiltrate the HVAC system. If you’re experiencing too much dust in the summer, your air conditioning unit could be aging out of its optimum efficiency and may no longer able to remove this dust from your air. Repairing and replacing ductwork may not cross most homeowners’ minds, but the joints and seams of your ducts can deteriorate after ten years, just like your air conditioner.
Oh, the Humidity
Not counting the necessity of a humidifier in the bedroom for someone with a nasty case of sinusitis, you expect your home to be at a manageably low level of humidity. High humidity in the home may seem like a comfortable bulwark against dry skin, but it actually turns your home into a fertile breeding ground for mold, fungus, bacteria, dust mites, and many more allergens. Perhaps less obvious is the effect that high humidity has on the building materials that compose your home. When humidity levels skyrocket, they spur on the release of toxic gases from processed and treated wood, carpet, paint, and fabric. This phenomenon, known as “off-gassing,” is most evident when a home is first built—you may know it better as “that new-house smell.” But that smell is the smell of formaldehyde, phenol, and other volatile compounds that are harmful to your health. If you smell these odors in what is decidedly not a brand-new house, it could be the result of high humidity from an HVAC system that can no longer properly regulate the quality of your air. Take this as a sign to get moving immediately on a new furnace or air conditioner.
Bills, Bills, Bills
If you aren’t scheduling annual HVAC maintenance checks and getting yearly reports on the state of your system, your energy bills can tell the story of your system’s performance levels. If you notice that your energy expenses are inching ever upward from month to month, the story they’re telling is probably a tragedy. As efficiency declines over the lifespan of an HVAC system, the furnace and AC necessarily require more gas and electricity to do the same work of heating and cooling your home, and that means you’re going to pay for it. Your first impulse may be to explore installing a programmable, or “smart” thermostat that learns your usage patterns and adjusts your HVAC energy expenditures accordingly. This is indeed a smart move that prevents energy from going to waste while the house is empty during the day or while people are sleeping. But if you’re still paying suspiciously high bills, especially if this is coming near the end of that 10-year or 15-year life cycle, you may be treating the symptom without addressing the root cause—a system that needs full replacement.
In Summary
Abundant dust, high energy costs, and high humidity are all telltale signs of an HVAC at the end of its usable lifetime. In conjunction with these warnings, bearing in mind that you can reasonably expect about 10 years from your air conditioner and 15 years from your furnace will help you tell how to know it’s time to replace your HVAC system. While it can be frustrating to replace a furnace or air conditioner when you’ve worked so hard to ensure high performance over its lifespan, who knows what the future holds? The HVAC systems of tomorrow could last longer than ever.
