Answers to the Top 7 HVAC Questions

As we move into the heating season, our customers are beginning to ask us questions about their furnaces and boiler systems. We thought we’d answer a few of those questions we get asked most often!

Here at Comfort Aire Heating & Cooling, we get lots of questions all year long, whether we’re servicing air conditioning systems or installing new heating equipment in homes and businesses around the Lancaster County area. People are curious about HVAC. And, we realize what we do may seem complicated and technical, but we’re always happy to educate our valued customers! After all, you live with and use your HVAC systems every day – we want you to feel comfortable with this equipment.

What is HVAC?

First, while we may sometimes forget, we realize many people don’t know what the letters H-V-A-C stand for! The answer is Heating, Ventilation, and Air Conditioning.

HVAC technicians, like our install and service teams here at Comfort Aire, specialize in setting up and maintaining these systems that keep your home warm in the winter and cool in the summer. This equipment can also help humidify or dehumidify the air in your home, which leads us to our next question…

What is the ideal indoor humidity level?

The short answer to this question is that it varies related to the temperatures outside and inside your home. In other words, your ideal indoor humidity level will generally be a bit different in the middle of summer when air conditioning is running vs. during the heating season in the middle of winter.

When we talk about humidity levels in our homes, we express the amount of water in the air as “relative humidity” or RH. Owning a device called a hygrometer, which measures RH, will allow you to instantly know how humid it is, though you’ll often be able to feel excessively high humidity. If you would describe your house as feeling “muggy” or “sticky” inside, your RH is much too high.

So, what are the numbers you want to see on your hygrometer?

According to industry recommendations, the ideal relative humidity for human health and comfort is between 40-50%. During the winter, when the temperature in your heated home is much higher than the temperature outdoors, you may need to achieve an RH of less than 40% to prevent condensation from forming on windows. Luckily, winter air is typically much drier, so getting to that lower RH isn’t usually very difficult. In fact, you may find you need to add moisture back to the air with a humidifier.

Paying attention to RH in your home is very important, as high humidity can create a long list of issues for your health and even your house’s structure. One of the biggest problems persistently high RH can cause is mold growth, often in areas you may not be able to see, like within crawlspaces or behind walls. And as mold grows, it can trigger allergic reactions and illness even in individuals who aren’t typically sensitive. It also contributes to indoor air pollution.

What is indoor air pollution?

According to the US Environmental Protection Agency (EPA), indoor air pollution has many causes. For air to be healthy, it needs to be fresh and clean and have the proper RH on a regular basis. Unfortunately, there are lots of enemies to those healthy aspects, and some you probably have never even considered.

Indoor air pollution sources include:

  • Malfunctioning heating and cooling equipment
  • Smoking tobacco inside your home
  • Air freshening products and other aerosol sprays
  • New furnishings or carpeting that is “off-gassing”
  • Excess moisture that can cause mold growth

The “V” in HVAC stands for ventilation, of course, and that is often the solution to ridding your home of indoor air pollution. While outdoor air also contains pollution, exchanging indoor and outdoor air through a filtration system (like that built into your furnace and/or air conditioning unit) helps keep indoor air pollutants from building up and creating health hazards. But, it’s important to remember that filters must be changed regularly to remain effective.

How often should I change my furnace (or air conditioner) filter?

There are a few factors to consider when deciding how often to change your filters. Furnace and AC system filters come in a variety of sizes based on how your equipment was manufactured (you can often find this size information printed on the door to the filter compartment), though the dimensional size of the filter you need will not really affect how often it should be changed.

Filters are also available in a variety of thicknesses between about 1” and 5” with different filtering abilities. Thicker filters usually won’t need to be changed as often as thinner ones since they can hold more pollutants like dirt, pollen, and dust before becoming clogged.

So why not always choose the thickest filter you can find and cut back on change frequency? Unfortunately, not all system configurations will accept the thickest filters on the market, and jamming an ill-fitting filter into your furnace or AC system can cause mechanical damage. If you’re having trouble finding a filter to fit your system, we can help!

As a general rule of thumb, we recommend replacing one or two-inch thick filters at the start of each season, and then every 3 months during your equipment’s operation. Four-inch filters can usually be changed two times per calendar year, at the start of “summer” (April/May) and the start of “winter” (October/November) when you make the switch between heating and cooling and back again. Five-inch filters can be changed once per year.

You may need to change your furnace filter more frequently if:

  • You keep your doors and windows open a lot, which lets in pollen and outside air pollution
  • You or members of your household smoke indoors
  • You have furry pets
  • You have recently completed an extensive home renovation project that involved creating lots of dust or installing new carpeting.

You will also need to consider the filter’s efficiency, which will often be expressed in terms of micron particle size. That is, how small of a pollution particle is the filter stopping? The larger the micron size number, the less efficient the filtering, which usually translates to a lower price tag on the filter. But is buying a less expensive filter worth the savings?

Should I buy the expensive air filters or are the cheap ones okay?

The air filters for your HVAC system do a lot of work behind the scenes, removing dust, mold spores, allergens, and other contaminants from the air that you and your family breathe. Air filters also keep the motor in your HVAC system clean, enabling it to work more efficiently.

As your heating and cooling system operates, the air filter fills with fine dust and particles that eventually block the airflow to your system. When these filter clogs form, the system’s motor works harder to maintain the temperature in your home, which is why it is so important to change your system’s air filter at regular intervals.

So what does this have to do with whether you need to buy expensive filters for your system? Really, it depends upon your priorities and whether you or any of your family members have known allergies or other respiratory conditions, like asthma.

The cost of the filters you use often depends on their MERV rating, which is related to the filter’s efficiency, as we discussed in the previous answer section. MERV stands for Minimum Efficiency Reporting Value, which was developed by the American Society of Heating, Refrigeration and Air Conditioner Engineers, or ASHRAE. (The HVAC world sure is full of abbreviations, isn’t it?)

Look to the MERV rating system as a way to know the size and type of contaminants that a particular filter can remove from the air. The higher the MERV rating number, the more pollutants the filter can trap. And there are many different filter materials available in each rating class, as well. These are some of the most popular you’ll find on the market:

Spun fiberglass filters

Typically the most affordable, spun fiberglass and other synthetic material-paneled filters provide the minimum recommended protection for your HVAC system with a MERV rating of 1-4. These will trap particles no smaller than most pollen, dust mites, sanding dust, and carpet fibers.

Disposable pleated paper and polyester filters

These filters are usually mounted in a cardboard frame and offer next-level MERV ratings of between 5 and 7. They will filter out pollutants like mold spores, cement dust, and aerosolized hairspray.

Box and bag filters

These are the very non-technical names for many rigid, cartridge-style filters that can use a variety of media, including “microfine” fiberglass and paper, and may be specially designed by your system’s manufacturer. They will feature MERV ratings between 9 and 16, which is the highest number on the MERV scale, excluding HEPA filters.

HEPA filters

HEPA stands for “high-efficiency particulate air,” and these impressive filters can remove the finest pollutants, including many hazardous biological contaminants. They carry MERV ratings of 16+ and are suitable even for hospitals and cleanrooms in manufacturing environments.

Beyond your personal priorities of cost vs. health-related concerns for your indoor air, the filter you should choose will depend on the manufacturer’s recommended MERV rating for your HVAC system. While it might seem like getting the filter with the highest MERV rating would be the best decision, regardless of cost, that is not always the case. Some systems are not built to work with high MERV-rated filters, so using them could cause your system to work harder and shorten the life of the motor.

When should I service my HVAC system?

Your HVAC system has many moving parts, and it needs to receive regular maintenance from professional, trained technicians. As with your car, if you’re a handy sort of person, you may be able to make some adjustments to your system yourself (especially those all-important filter changes), but system inspections and tune-ups are best performed by service personnel who do this work every day.

Having your HVAC system serviced at least once per year is a good rule of thumb, though we recommend a seasonal service schedule if you have both central heating and air conditioning systems in your home, as most people do these days. Basically, before you turn on your system for the season, it’s a great idea to have a technician look for problems that may lead to emergencies if not addressed.

Are HVAC service contracts worth it?

As we discussed in a previous post here on the blog, HVAC service contracts have a lot of advantages for busy homeowners. Most importantly, these plans drastically reduce emergencies because your system is being regularly monitored. You will likely not experience a breakdown because your contract assures that your HVAC partner knows exactly what is going on with your systems over time. And, if you do have an emergency, you will likely receive priority response service. What’s more, here at Comfort Aire Heating & Cooling, our maintenance contract customers receive a 10% discount on all parts!

We hope that our answers to some of the biggest HVAC questions on our customers’ minds have helped you learn more about your heating and air conditioning equipment! If you still have questions or want to save money on maintenance with a new service contract, get in touch with us today!

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