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 they exhaust their flue gases. The 80% furnaces still use a 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.
To help increase the actual efficiency of your furnace, and to make sure that you are keeping the air that you are paying to heat in your home, Arctic Heating & Cooling recommends to have home performance testing done on your home.
If you are an Illinois homeowner and you plan to live in your home for five years or more, I wouldn’t recommend considering the 80% AFUE furnace. If you are an Illinois homeowner, you probably spend more money heating your home than you spend on all of your other appliances put together. It makes complete 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% furnace will initially cost you less money. 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.
Single Stage, Two Stage or Variable Speed?
Whether you choose an 80% AFUE furnace or a 90% Plus AFUE furnace, you will have three different furnace options in that category. You will have to choose between the Single Stage, Two Stage or Variable Speed.
The Single Stage furnace is the traditional furnace design of the past. In the past the Single Stage furnace was the only option. 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 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 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.
Choosing an air conditioner should be a little bit easier than choosing a furnace. You will need to decide how efficient you want the air conditioner to be, you will have to decide if you want a Single Stage or Two Stage unit, and you will need to decide if the sound output level of your condensing unit is going to be an issue.
What does SEER mean?
One of the decisions you need to make is how efficient you want your air conditioner to be. You will have to choose an air conditioner between 13 SEER and 21 SEER. The SEER rating on an air conditioner is a lot like the miles per gallon rating on a car. The higher the SEER rating, the less electricity it will use to cool your home.
Single Stage or Two Stage?
Two Stage air conditioners offer many nice benefits. They have two different cooling outputs (Half Power Cooling and Full Power Cooling), depending on what the thermostat tells the air conditioner it needs. The thermostat will base that decision on the temperature of the house. Example: If you have a 5 Ton two stage air conditioner, the thermostat will call for first stage cooling (2.5 Tons) first. On mild days it will cool your home on first stage without a problem. If it cannot satisfy the thermostat, the thermostat will tell the air conditioner to activate the second stage (5 Tons). For a very large portion of the year a two stage air conditioner will cool your home without ever needing to ramp up to second stage. When it’s running in first stage, it’s using about half the electricity, but only putting out about half the cooling. A Two Stage air conditioner will run for a longer period of time than the Single Stage air conditioner, but the longer an air conditioner runs the more evenly it will mix the air in the home and the more humidity it will remove from the air. If you experience uneven temperatures (hot and cold rooms) in your home during the cooling season, the Two Stage air conditioner should help or even eliminate this problem. If you experience higher than normal humidity levels in your home during the cooling season, the Two Stage air conditioner should help or even eliminate this problem. If the sound output level of your air conditioner is important (this is usually the case if you like spending time outside your home and the air conditioner bothers you when it runs) you should consider a Two Stage air conditioner.
Sound output level
If you like spending time outside your home, you should find out about the sound output level of each air conditioner you are considering (especially if your air conditioner is near an area where you entertain company). The higher SEER units and the Two Stage units tend to be quieter than the low SEER Single Stage air conditioning units.
Which air conditioner makes the most sense?
When selecting which air conditioner to invest in, I highly recommend balancing that decision with the amount of time you plan on living in the home and your expectations. If you are staying for 5 or more years, I would recommend a 15 to 21 SEER air conditioner. If you have excessive humidity in the summer or the sounds of your air conditioner disturbs you or your company, I would recommend a Two Stage 19 to 21 SEER air conditioner. I chose a 19 SEER Two Stage air conditioner/heat pump for my home. Many of my customers have installed this same unit 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.