FURNACE 101 FOR THE MODERN HOMEOWNER
Many of us aren't sure where to begin when it's time to upgrade or make changes in our heating and cooling systems. With the wide range of equipment available to modern homeowners, the options can be a little intimidating and confusing. One thing is for sure, though: it is better to prepare and familiarize yourself with the options beforehand, than to be forced into a hasty (and possibly regrettable) decision after your furnace bites the dust in the middle of a cold, blustery January night, and you need to get heat back into your home RIGHT NOW.
Several things will need to be considered in determining the best time for you to replace your existing furnace. The condition and energy efficiency of your existing unit will obviously be the first considerations. Factors such as the make, model, and age of the furnace will require some contemplation, as well. With modern technologies allowing significant increases in the energy and operating efficiency of home heating systems, it may be worth the savings in energy costs to upgrade your system somewhere in the ball park of every 10 years. At the same time, it must also be acknowledged that well maintained, high quality equipment can and many times does last many years longer than this general time estimate.
How do I determine the proper size furnace for my home?
To get the best performance out of a new furnace, it is simply not as easy as replacing the old one with a carbon copy of your existing unit. Determining the size of the furnace you need will probably require the help of an HVAC professional who is up to date on industry and governmental energy standards. They can perform a heating load calculation, in order to give you a more accurate quote on the type of system your home requires.
This evaluation will consider any changes that have been made to your home since your current furnace was installed, such as new exteriors, new doors, new windows, and possibly even new appliances which have been added to your home.
Proper sizing of your furnace is important. Many people underestimate the amount of time that a furnace actually needs to run to provide proper comfort for your home. When the thermostat registers that the air around it has reached the called for temperature, it sends a shut-off signal to the furnace. While the air around the thermostat may have reached the desired temperature, the furnace may not have run for the amount of time needed to warm all areas of the home, such as upper floors. You may need your furnace to run longer to provide more even comfort. Many homeowners have furnaces that are oversized for their homes. If your furnace cycles on and off frequently, it may be too large, and is not heating your home properly or efficiently.
It is generally estimated that most homes up to 1,800 square feet will be sufficiently heated with an 80% AFUE furnace. A larger home will generally be more comfortable with a 90% AFUE furnace. Of course, each home is as individual as the people living in it. The best furnace is going to be one that has been sized correctly for the needs of your particular home, and has been properly, professionally installed.
What is AFUE?
Annual Fuel Utilization Efficiency = AFUE. Your furnace's AFUE number tells you how efficiently your furnace is converting fuel to energy, as opposed to how much is lost as exhaust. An 80% AFUE furnace converts 80% of the fuel you purchase into heat for your home. A 90% AFUE furnace or a 90% + AFUE furnace will convert 90% or more of fuel into the energy that heats your home. Some manufacturers offer furnaces with higher efficiencies than others.
Can I use my chimney?
As industry technology moves forward, many existing masonry (brick) chimneys are simply not equipped to properly meet the ventilation demands of modern furnaces. The size of the chimney can be an issue. It might be too large for your new furnace. The result could be improper ventilation of flue products, which can lead to condensation issues inside the chimney. There are at least two major problems with condensation in the chimney. Corrosive acids are formed when flue gases combine with water condensate. These acids then eat away at the chimney itself, destroying bricks, tiles, and mortar. Also, the freezing and thawing of moisture in winter can cause the breaking away of mortar and bricks. The resulting damage can create leaks into the home that will also allow damage to drywall, and can drain back into the furnace itself, causing corrosive issues there, as well.
The type of furnace you install will determine the way the furnace exhaust leaves your home. If your current furnace vents into a brick chimney, with the installation of a new 80% furnace you will also need to install an aluminum flue liner, if it does not already have one (most do not). The 90% models vent thru a PVC pipe, which usually exits the home through the closest side wall. The 90% Plus furnaces require a drain for condensation that is created in the exhaust pipe.
There are homes where it is possible to match a new furnace to an existing chimney. Things to consider are the height, location, lining and condition of the chimney. Building codes have to be met. This ensures proper draft in the chimney for adequate ventilation. Our team of HVAC professionals can offer the best advice on how to configure your new furnace.
What type of furnace should I get?
In past decades, installing a new furnace didn't allow much in the way of options for what was available. Today's industry, however, can leave a homeowner's head spinning with all the choices now available.
New furnaces are surprisingly small and compact compared to their counterparts of yesteryear, but they pack a big punch for all their diminished size, in the form of more utilized fuel efficiency. Older larger furnaces were hopefully somewhere in the neighborhood of 65% efficient. Furnaces today are at least 80% efficient, and can go as high as 90%-plus in their efficient use of energy.
One of the most energy-efficient options chosen by many homeowners is a two-stage, or variable-stage furnace. This type of unit runs at a lower stage most of the time, conserving energy, and minimizes the fluctuating temperatures associated with a single-speed unit. The lower stage runs at enough capacity to heat your home and keep it comfortable on mild winter days. When temperatures drop, the furnace will then enter the second stage, to meet the demand for heat within the home. This will happen automatically without adjusting the thermostat. Some of the advantages a two-stage system offers are a more consistent level of heat in the home, with less fluctuation in temperature that can be common with a single stage furnace. Because a two-stage furnace starts in its lower stage and runs in the lower stage most of the time, it uses less energy to operate, and produces less noise in the home than furnaces that turn on at full blast.
As two of the largest and most respected manufacturers in the industry, American Standard and Bryant, among others, offer a range of top-performance, energy-efficient single-stage and variable-stage gas furnaces that will keep your home comfortable all winter. A matched system (furnace, air conditioner, air cleaner) can raise your year-round comfort level even more, with equipment designed to work seamlessly together to enhance overall performance.
Why not call us at 314-849-7900 today and request a consultation? Our highly competent team of certified HVAC professionals will be happy to assist you in ascertaining the best choices for your family's home comfort needs.