Help Choosing a Furnace For Your Home


Choosing A FurnaceWhen you are looking for a new furnace in Chicago's suburbs, Perfect Air can help you with FREE friendly advice, and a FREE estimate.

There are several issues to consider in choosing a new system. Please note that these are only general observations, it is important to have a professional in-home inspection for advice with your own specific needs and a comparison with your existing system.


Furnace Efficiency Options

Most equipment manufacturers offer about 6 different furnace options. The first decision you need to make is how efficient you want your furnace to be. You will have to choose between 80% AFUE furnaces and 90% Plus AFUE furnaces. The next decision you need to make is which options you want with your furnace. Your 6 options are as follows:

- 90% Plus AFUE - Variable Speed, Two Stage, Two Pipe
- 90% Plus AFUE - Two Stage, Two Pipe
- 90% Plus AFUE - Single Stage

- 80% AFUE - Variable Speed, Two Stage
- 80% AFUE - Two Stage
- 80% AFUE - Single Stage

What does AFUE mean?

AFUE stands for Annual Fuel Utilization Efficiency. In layman's terms, a furnaces AFUE rating equals the amount of gas a furnace uses. The rest of the gas the furnace doesn't use goes out the chimney. So the 80% AFUE furnaces use 80% of the gas you're paying for and waste the other 20%. 90% AFUE furnaces waste 10% of the gas you're paying for and 95% AFUE furnaces waste 5% of the gas you're paying for. If your existing furnace is 15 years old, chances are it is probably about 65% to 70% AFUE. 20 year old furnaces can be as low as 60% AFUE or less.

80% AFUE or 90% Plus AFUE furnace?

The biggest difference between the 80% and 90% Plus AFUE furnaces is the amount of gas they waste. The 80% furnaces waste 20% of the gas you pay for. The 90% Plus furnaces only waste about 5-10% of the gas you pay for (this percentage depends on the make, model and brand of furnace you purchase). They are called 90% Plus furnaces because they are 90% or more efficient. Some manufacturers offer furnaces with higher efficiencies than others. Another difference between the 80% and 90% Plus furnaces is the way the exhaust leaves the house. The 80% furnaces still use a traditional metal pipe for their exhaust. If your furnace is currently being vented into a brick chimney and you decide to purchase an 80% furnace, you will need to protect the chimney with an aluminum liner (if it does not already have one - most don't). The 90% Plus furnaces use a PVC pipe for their exhaust. This PVC pipe usually exits the home through the closest side wall. The 90% Plus furnaces do require a drain for the condensation that is created in the exhaust pipe.

Illinois Homeowners

If you are an Illinois homeowner and you plan to live in your home for five years or more, I wouldn't recommend the 80% AFUE furnaces. You probably spend more money heating your home than you spend on all of your other appliances (including your air conditioner) put together. It makes great financial sense to get the most efficient furnace you can to cut down your gas bills. If you don't plan on living in your home for a long period of time, the 80% furnaces will initially cost you less money (which could make the most financial sense for that situation). One thing to keep in mind: a prospective home buyer may hesitate on purchasing a home with an 80% furnace and if for some reason you end up staying longer than expected, you will be stuck with the higher gas bills. The price of natural gas has continued to rise and will continue to rise forever. All it takes is some type of natural disaster or act of terrorism that disrupts the U.S. supply of natural gas and our gas prices could easily double or triple over night. If that happens, you will really wish you had that 90% Plus efficient furnace.

Single Stage, Two Stage, Variable Speed or Communicating?

Whether you choose an 80% AFUE furnace or a 90% Plus AFUE furnace, you will have a few different furnace options in that category. You will have to choose between the Single Stage, Two Stage, Variable Speed or Communicating.

The Single Stage furnace is the traditional furnace design of the past. In the past the Single Stage furnace was the only option available. When the thermostat calls for heat, the furnace comes on (full power) until the thermostat reaches the set temperature. Example: If you have a 100,000 BTU single stage furnace, it will come on and run at 100,000 BTU's until the thermostat is satisfied. Having a single stage furnace is like having a stove with only two settings - OFF & HI HEAT.

The Two Stage furnace has a couple of nice benefits. It has two different heat outputs (Half Power Heat and Full Power Heat), depending on what the thermostat tells the furnace it needs. The thermostat will base that decision on the temperature of the house. Example: If you have a 100,000 BTU two stage furnace. First stage will come on (50,000 BTU's) first. On mild days it will heat your home on first stage without a problem. If it cannot satisfy the thermostat, the thermostat will tell the furnace to activate the second stage (100,000 BTU's). For a very large portion of the year a two stage furnace will heat your home without ever needing to ramp up to second stage. When it's running in first stage it's using about half the gas, but only putting out about half the heat. The Two Stage furnace will run for a longer period of time than the Single Stage furnace, but the longer a furnace runs the more evenly it will mix the air in the home. If you experience uneven temperatures (hot and cold rooms) in your home during the heating season, the Two Stage furnace should help or even eliminate this problem.

The Variable Speed furnace has several benefits. It is often referred to as the Cadillac of furnaces, because of the comfort it delivers. To start, the Variable Speed furnace has two stages like the above furnace. So, you can expect the benefits that come with the two stage furnace, along with everything the Variable Speed offers. The thing that makes the Variable Speed furnace so much better than the others is the blower motor. Your blower motor runs during the heating mode, it runs during the cooling mode, and if you run the thermostat fan switch in the on position (which I highly recommend) - your fan is running 24/7/365. Needless to say, the fan is one of the most important parts of the furnace to consider. Single Stage and Two Stage furnaces have one set fan speed for heating and one set fan speed for cooling. Whether that setting is too high or too low for your duct system, that's what that furnace will put out. The blower motor on a variable speed furnace has no set speeds. It adjusts itself to your duct system. It constantly measures the pressure in your duct system and adjusts itself so that you always have the correct amount of airflow. This motor runs off a different voltage (DC voltage). Because of the technology, it costs MUCH less to operate than all other motors. Variable Speed furnaces are the quietest furnaces you can buy, they're the most efficient furnaces you can buy, they clean the air better than any other furnace you can buy, and most air conditioners are rated about 1 SEER more efficient when combined with the Variable Speed furnace.

What is a two pipe furnace?

The variable speed, and two stage 90% Plus furnaces come with the option of a second pipe. The second pipe allows the furnace to draw its combustion air from outside the house. This is a nice benefit that you can't get with the 90% Plus Single Stage and all 80% furnaces. Furnaces without a second pipe draw their combustion air (the air needed for the flame to burn) from inside the home. The whole time these furnaces run they are blowing your indoor air right out the exhaust pipe. When you exhaust out indoor air, you put your home under a negative pressure. Your house wants to replace all of the air that it blows out. It replaces that air by pulling in air from every place that it can find (windows, doors, cracks etc.). This is what makes your home feel drafty. With a two pipe furnace you are bringing in air through one pipe, burning it and sending it right out the exhaust pipe. With a two pipe furnace, you are not putting your home under a negative pressure every time it runs.

Which furnace makes the most sense?

When selecting which furnace to invest in, I highly recommend balancing that decision with the amount of time you plan on living in the home. If you are staying for 5 or more years, I would HIGHLY recommend the 90 Plus Variable Speed furnace. That is the furnace I chose for my home. A large percentage of my customers have installed this furnace and love it just as much as I do. If you have limited funds and you can't afford the best furnace and the best air conditioner money can buy, I would recommend spending the extra money on the better furnace. The furnace will pay you back faster and will offer benefits during the heating and cooling season.



Before any installation begins, we have an evaluation and estimate process. A comfort consultant will come to your home and start by asking a few questions. These questions will help the consultant figure out what systems to recommend to you, and what changes we may need to make during the installation to fix some of the existing problems you may have in your current system. The consultant will then evaluate your existing system. After a thorough evaluation, he or she can sit down with you and explain what we have seen, make logical recommendations, and leave you with a few options and exact pricing on systems that will fit your needs.

High Efficiency Systems

We install high efficiency comfort systems designed to be the most cost-effective on the market. I know it may be hard to believe, but technology has created systems that (for some customers) offer as much or more than a 50% reduction in energy bills. Whether you own a condo or a 20,000 square ft. office building, we have a cutting edge system that can help you achieve the savings you deserve. Ask us about all the options we have to fulfill your particular high efficiency needs.

What’s included?

When we give you a bid for a new system, we make sure that the quoted price includes everything we need to complete the job. We also list everything included on a printed proposal. If we forget to include something you need in our proposal, we will add it and you won’t pay for it. Rest assured that the price we give you is the exact price you will pay at the end of the installation. No hidden charges or fees, and taxes are already included in the price.

Equipment Warranty

Every furnace & air conditioner we install comes with our industry leading 10 year parts & labor warranty. For 10 years you won’t have to pay a single penny for any repairs. Problems caused by an act of God, equipment neglect or misuse are the only issues that may not be fully covered by our warranty. All 80% AFUE furnaces come with a 20 year heat exchanger parts warranty, and all 90% (or higher) AFUE furnaces come with a lifetime heat exchanger parts warranty. Some models actually come with a furnace replacement heat exchanger warranty (call for more details on this particular warranty). To keep these warranties valid, you must have each unit cleaned and checked by us once a year. This warranty is transferable to any new homeowner.

The Installation Process

When we come to your home to install a new system, our installation team will begin by introducing themselves to you. They will put covers over their boots, and cover the walking path (with painter’s tarps) between the door they will be entering from and the work area (so the working path will be protected). Then they will walk through the install process with you. They will explain all the steps involved and will discuss the placement of each unit (to make sure everyone is on the same page). When the installation is complete, they will review a checklist to make sure everything is complete and fine tuned to manufacturers specifications. Finally they will take you on a test drive and explain how your new system works.


For FREE friendly advice and a FREE estimate for a new or replacement furnace for your home in Chicago - all backed by a satisfaction guarantee - call Perfect Air & Heat today.


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