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4 Answers To Common HVAC Questions

Posted by Brittany on Sep 4, 2015 11:50:16 AM

If you are in the market to buy a new HVAC system, or just want to know the answers to some of the most common HVAC questions, then you’ve found the right article. Homeowners want answers about everything from filters to furnace efficiency and upgrading air conditioners to indoor air quality. We’ve narrowed down a few of the facts to give you the simple answers to your FAQs (Frequently Asked Questions).


1. Is it worth spending money on a high efficiency furnace, and will I really save what those numbers on the manufacturer’s list tell me I will save?

It’s not just a marketing ploy. Those numbers you see on the tag or manufacture’s list are telling you how much it costs to run HVAC equipment annually (like furnaces and ACs) and how much you can save are put together by a third party. You can trust their accuracy, because the certified ratings are done by independent agencies: the Air Conditioning, Heating and Refrigeration Institute (AHRI) and the U.S. Department of Energy’s ENERGY STAR program. Both test and rate performance of different HVAC products to make sure they meet specific energy efficiency standards.

According to Keith Hill, technical support manager for Minnesota Air, they look at AFUE (annual fuel utilization efficiency) for furnaces. According to Keith, AFUE is a percentage of the heat transmitted into the home as compared to the total amount of heat the furnace produces. The heating capacity in a furnace is referred to in British Thermal Units per hour (BTUH).

“As an example, a 100,000 BTUH furnace rated at 80% AFUE will send 20% (20,000 BTUH) of the heat it produces up the chimney and 80% (80,000 BTUH) of the heat into the home,” he says. “So, a change to a 95% AFUE furnace will give the homeowner an increase of 15% fuel savings (95% - 80% = 15%). Using that same example, the new 100,000 BTUH furnace will provide an additional 15,000 BTUH into the home, 15% more heat.”

Note that you may have other gas appliances (for example a gas stove), so it may not be 15 percent saved on your total gas bill.

2. How do I pick the right filter for my HVAC?

This is such a common question, we wrote an entire article about just filter basics and one on how to choose one for your HVAC. The quick answer is to look to your operation manual or consult a pro if in doubt. Our expert Keith says always to use an ‘air cleaner’ if you can. Those are the filters in a cabinet that are 5 to 10 inches wide. The downside to air cleaners is that the width may require ductwork changes, but it’s well worth it.

“They have media filters with lots of surface area so you can get a higher efficiency filter without sacrificing airflow and you don’t need to change them so often,” Keith says. “Many times, only twice per year.”

He reminds homeowners to think about air flow and that using the 1-inch thick high efficiency filters are too restrictive and in many cases can do damage to your HVAC equipment.

3. I live in Minnesota and the summer is short, so do I really need a high efficiency air conditioner? Is it worth the price?

Many consumers wonder if their air conditioner runs enough to justify the upfront price increase of buying a high efficiency AC, and if they’ll get the money back in energy saved over time. They may only think of buying a high efficiency AC as just a way to save money on energy costs – but it buys more than just energy savings. According to Keith, mid- to upper-tier AC units are not only more efficient, they are also quieter, easier to maintain, and in some cases carry a better warranty.

So that means the answer for you will depend on a few of those factors.

“If you don’t mind a little heat and seldom use your AC in a normal Minnesota summer, then you probably won’t see a payback,” says Keith. “Look at all of the features, including efficiency, when making a purchase decision.”

4. If I get a new furnace, do I need to get a new AC at the same time? (Or Vice Versa)

Keith says the answer is no, but that it will save you money if you do.

“Combining the two projects into one saves you money simply because it’s more cost effective for the HVAC pro to install both at the same time,” he says.

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Topics: HVAC