Expert Answers to Popular HVAC FAQs

Homeowners in Central Wisconsin know that the pros at Merrill Sheet Metal Works are here whenever they need help. From common concerns to popular HVAC FAQs, our experts are happy to share their knowledge to better educate you about your home comfort. Read through the common questions and answers below to learn when you should change your filter, how often you need furnace maintenance, and what’s included in an annual tuneup.

What does the flashing light on my furnace mean?

Most modern furnaces have a red light—an indicator light— on the furnace door that tells you it’s getting power. It can also tell you when something’s wrong. If yours is flashing, pay attention to how many times it flashes before it pauses. (i.e. flash…flash…pause…flash…flash…pause.) Your furnace should have a chart that tells you what the number of flashes signifies, like a clogged filter or open pressure switch. If you’re not able to decipher what the flashing means, call a professional like Merrill Sheet Metal.

How often do my furnace and air conditioner need maintenance?

Your furnace and air conditioner both need maintenance at least once a year. It keeps them running safely and efficiently, lowers your chance for breakdowns, helps you save money on energy bills, and extends system life. Even if it’s been a few years since your last cleaning and inspection, you should still call for a professional tuneup to get your system back on track. Sign up for our Peak Performance Maintenance Agreement and we’ll remind you when it’s time for service—you don’t have to worry about a thing.

What is included in annual maintenance?

Think of annual maintenance as a wellness check for your furnace and air conditioner. Our experts will thoroughly inspect, clean, test, and adjust all vital parts to ensure your system is working at its best. And check filters, voltage and amp draw, condensate drains, heat exchangers, blowers, burners, and so much more. We’ll tell you about any concerns or repairs that are needed, and let you know if your system will need replacement soon. See a full list, plus maintenance benefits on, our maintenance agreement page.

What is the difference between a heat recovery ventilator (HRV) and an energy recovery ventilator (ERV)?

Heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs) are air-to-air exchangers that bring fresh air into your home to enhance air quality. While they essentially do the same thing, they do it differently. HRVs transfer heat from one air stream to another and are used more often in areas where high humidity is a concern in winter because they help remove excess moisture. ERVs transfer both heat and moisture and are used in areas where there isn’t excess humidity during the winter months. Not sure which is right for your home? We can help.

How can I save money on my energy bills?

Here are some simple things you can do to lower your energy bills:

  • Replace your air filter regularly to keep air moving efficiently.
  • Adjust your ceiling fan to rotate clockwise during winter and push warm air that rises back down. Switch its direction to rotate counterclockwise during summer.
  • Consider a programmable thermostat to better manage your home comfort when you’re home and away.
  • Schedule annual maintenance to keep your system clean and improve its efficiency.
  • Keep vents open—don’t close them off, even in rooms you don’t use often. This makes your system work harder and raises energy bills.
How do I know if my air filter is clogged?

Check to see if your filter is noticeably gray in color and watch for these signs:

  • Higher energy bills
  • Frozen evaporator coils and ice on your air conditioner
  • Uncomfortable home (not feeling as much heating or cooling as you used to)
  • Excess dust and dander in your home
  • No heat coming from your furnace

Ask a Merrill Sheet Metal expert to weigh in if you suspect an air filter clog.

Should I be worried about my indoor air quality?

Indoor air quality continues to be a major Environmental Protection Agency (EPA) concern so we urge homeowners to have theirs checked. We use the AirAdvice® test to pinpoint air quality levels and make accurate recommendations accordingly. Our Bryant® Indoor Air Specialists are trained to find problems and suggest products to alleviate them, like humidifiers, dehumidifiers, air purifiers, and more.

Why is my thermostat screen blank?

Replace your batteries to see if this restores your read out. If that doesn’t do the trick, check your circuit breaker to make sure you don’t have a tripped circuit. If not, there may be a bigger issue at hand, like loose wiring or a bad connection. You’ll need a professional to diagnose and fix the problem and we’re happy to help.

Still have questions after reading through these common questions? Ask us online or give us a call at 715-536-2262.