When your furnace meets the following criteria, it’s usually best to replace it.
1. It’s 15 Years or Older
According to the U.S. Department of Energy, furnaces last 15-30 years and then will start to require major HVAC repair services. If you've been keeping preventative maintenance appointments regularly, your furnace may be in decent shape at the 15 year mark but you'll soon have components breaking down. You can think of your HVAC unit being similar to an old car: minor repairs here and there are one thing, but you never know when the big ticket part will fail.
There’s no getting around it - sometimes the biggest factor is just the age of your system. If it’s 12–15 years old (or older), and you're noticing a decline in performance or comfort, start exploring your options. Plus newer models offer significant improvements in energy efficiency, smart thermostat integration, and lower cooling costs.
Upgrading to a new AC system or gas furnace can also qualify you for tax credits and other home improvement incentives—plus it’ll shrink your carbon footprint.
You can think of your HVAC unit being similar to an old car: minor repairs here and there are one thing, but you never know when the big ticket part will fail.
While it can be tempting to ignore small issues with your current system, there are several red flags that might suggest it’s time for more than a quick fix. Understanding these signs will help you make the best decision for your comfort, your wallet, and your home’s long-term value.
The Cost of a Furnace Repair is Half as Much as a New Unit
It’s hard to swallow the price of a brand new furnace, but it’s just not wise to dump half the value of a new unit into fixing an old one. You should consider an HVAC repair if it costs less than half of a replacement, but if your old furnace is over 3/4 of its life expectancy and you're looking at a big chunk of change to fix it, replace it.
2. You're Constantly Calling for HVAC Repair Services
We love to see our customers, but if you just had Crystal in your home last year to fix a blower motor, last month to fix an ignition switch, and now there’s a strange grinding sound coming from your furnace, it’s probably time to throw in the towel and spring for a new unit. Now keep in mind that we’re talking about an old unit. If your furnace is only a few years old and you’re dealing with a lot of repairs, we should talk about your warranty.
Again, the rule of thumb: if the cost of the repair is more than 50% of the replacement cost, it’s a strong sign that HVAC replacement is the better option.
As we mentioned, this is especially true if your unit is past the average lifespan of 10–15 years, (or if it uses outdated refrigerants like R-22 Freon which is being phased out for environmental reasons due to its impact on the ozone layer).
3. Your Heating Bills Have Gone Up
If your energy costs have crept up without a change in usage, your HVAC equipment could be the culprit, and it may be time for a furnace repair. Older systems, especially those lacking ENERGY STAR certification or a high SEER rating (Seasonal Energy Efficiency Ratio), tend to use more energy to deliver the same amount of cool air.
This spike in utility bills is often one of the earliest signs your HVAC system is losing efficiency—either due to age, poor airflow, or hidden issues like a refrigerant leak or malfunctioning fan motor.
Tip: Compare your recent bills to those from the same season last year. A sharp increase could mean it's time to repair HVAC components—or start pricing a new AC system.
4. Your AC Can’t Keep Up With the Heat
If your AC unit struggles to maintain the set temperature—even after a filter change or recent tune-up—it could signal deeper issues. Common culprits include refrigerant leaks, clogged condenser coils, or failing electrical components.
Any smart HVAC company will always check whether a simple repair is possible, but if your current system consistently underperforms during peak demand, it might be time for a new HVAC system with higher SEER ratings and smarter controls.
5. Strange Noises and Odors? Don’t Ignore Them
Grinding, rattling, and banging sounds are often signs of failing mechanical parts like belts, motors, or the heat exchanger. Odors—like burning dust or musty smells—can point to mold in ductwork or even electrical issues.
These are not problems to put off, especially in an emergency situation. Ignoring them could lead to a more expensive repair bill or the sudden failure of your entire system during a heat wave.
6. Indoor Humidity or Poor Airflow
Feeling sticky indoors or noticing uneven cooling? If airflow feels weak or humidity is high even when your AC is running, your HVAC needs attention. This could be due to leaking ducts, dirty coils, or blocked vents—issues that waste energy and stress your system.
If you’re dealing with this regularly, a new air conditioner or HVAC system replacement may be the more energy-efficient and cost-effective path in the long run.
When You Need HVAC Repair in St. Louis, Call Crystal!
We know making the decision to purchase a new HVAC unit is tough, so we promise to always be honest with our customers about furnace and air conditioning repairs.
Whether you’re facing frequent breakdowns, rising energy bills, or need emergency service, our team at Crystal is here to help. We’ll evaluate your system, provide an honest assessment, and guide you toward the best option for your budget and comfort.
Call our Phone Number today to schedule a consultation. Let’s make sure your HVAC Service delivers reliable comfort for years to come.
If for any reason you suspect a problem with your heating and cooling system or you want to discuss purchasing a new unit, just give us a call. We’ll be happy to examine your system and have an open, honest discussion about what’s best for your comfort and budget needs.
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