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Furnace and Heating System Questions



Can I use my chimney with my new furnace?

Furnace technology has advanced significantly in recent years, raising concerns over chimney use. As a result of changing technology, many existing masonry chimneys aren't able to meet the specific demands of new furnaces with higher efficiency and enhanced performance.

There are several reasons why new furnaces and existing masonry chimneys aren't compatible. The size of the chimney can be an issue. Modern, higher-efficiency furnaces transfer more heat into your home and less heat up the chimney than older, less-efficient units. While this means the consumer is getting more for their energy dollar, it also means that the existing chimney might now be too large for the new furnace. The result could be improper ventilation of flue products, which can cause condensation problems inside the chimney. Condensation in your chimney is the cause of two major problems. The water combines with flue gases and forms corrosive acids that eat away at the chimney, deteriorating tiles, bricks and mortar. Secondly, in winter, moisture freezes and thaws, breaking away mortar and bricks. Resulting damage can be extensive. A chimney can be destroyed and deterioration can create leaks into the home. Moisture can damage interior dry wall near the chimney and run back into the furnace, causing corrosion there, too.

In addition, today's induced-draft furnaces often require an additional natural draft appliance to be installed into the same chimney for proper venting.

Other possibilities for furnace-chimney incompatibility include the absence of a tile liner in the chimney and the location of the chimney on an outside wall of the home.

The difference between an unlined masonry chimney and one lined with tile is simple but significant. An unlined masonry chimney is constructed of only bricks and mortar. A tile-lined chimney has the same bricks-and-mortar exterior appearance, but it also uses a rectangular or round-fired clay tile pipe in the center. While all new masonry chimneys are built with a clay tile liner, this doesn't guarantee that they can be used with some new furnaces.

There are installations where it is possible to match a new furnace to an existing chimney. Certain factors such as chimney height and location, proper lining and condition of the chimney must be taken into consideration. Building codes must also be kept in mind. These requirements must be met to ensure proper draft in the chimney for adequate ventilation.

Your local Service Experts sales and service center can offer the best advice on how to configure your new furnace.

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Every time my furnace starts it makes a clicking sound, is that normal?
The clicking sound is likely the spark igniter on the furnace going through its sequence to light the furnace burners. This is normal. However, if you do experience louder and more frequent noises from your heating system you should contact your furnace repair technician for an evaluation. 
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My furnace has a viewport with blinking lights, what do they mean?
This port is a diagnostic tool furnace technicians use to help determine the operational status of the furnace.
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What are the pipes coming out of the tip of my furnace?
The pipes are the combustion exhaust vent and outside air intake. This type of heating system is referred to as a sealed combustion system.
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What is the difference between an 80% and 90% furnace?
An 80% furnace is often less expensive, is usually vented with a metal pipe, takes air from indoors for combustion, and is generally less efficient. A 90% furnace typically costs slightly more, and is vented with an exhaust and intake PVC pipes (does not take air from indoors for combustion). Most models have variable speed blower motors and are two-stage for maximum comfort.
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What is the water-like trickling sound when my furnace is on?
High efficiency 90% furnaces have a by-product of water vapor. This water vapor returns to the furnace through the exhaust PVC and is then drained. The sound is normal.
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What size furnace do I need?
Unless you are very familiar with HVAC industry energy standards and government energy standards, it's almost impossible to determine the size of a replacement furnace. A trained heating specialist knows all the standards and can evaluate your home for not only the heating appliance, but also the quality of the heated air, and how well the air is distributed in the home. This evaluation is called a heating load calculation and should be performed by a heating and cooling contractor before they provide a new HVAC system quote.

This home heating evaluation also takes into consideration changes made to the home since the last furnace was installed. New windows, doors, insulation, exterior changes and other appliances that may have a huge affect on the size of the furnace needed today. A consumer can tell a contractor the exact furnace they now have, but without a complete home analysis, it's impossible to determine the proper size of the replacement furnace equipment.
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What are furnace ratings?

Furnaces are rated by the Annual Fuel Utilization Efficiency (AFUE) ratio, which is the percent of heat produced for every dollar of fuel consumed.

Like the miles per gallon rating on your automobile, the higher the AFUE rating, the lower your fuel costs. All furnaces manufactured must meet at least 78 percent AFUE. If your furnace is 10 to 15 years old, it very well may fall below the current furnace minimum and waste energy.

This doesn't mean that you should only look for a furnace with the highest AFUE rating. The efficiency rating is just one factor to consider when looking at a new furnace.

Furnaces use electricity to run fans and motors. The amount of electricity used varies greatly depending on the type of furnace. Be sure to check electricity usage prior to making a purchase decision.

There are several important factors to consider when making a purchase decision. Payback is a big factor. For instance, if you live in a colder climate, you could see payback in a few short years. But in a more moderate climate, it could take longer. In this case you may consider purchasing a mid-efficiency furnace. Remember, after the payback, you will continue to save money on your energy bills.

Other considerations are how long you plan to live in your house, special comfort needs, fuel availability and fuel cost.

All these factors, plus your lifestyle and family needs, add up to show you which furnace is best for you.

Your local Service Experts sales and service center can assist you with finding the best furnace for your home.

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What is a variable-speed furnace?

The term "variable speed" refers to the furnace's indoor air blower motor. The blower motor is the component that determines the amount of air the blower is required to deliver to your home.

When your furnace is installed, the speed and airflow for your home are set depending upon your specific situation, such as the size of your home, etc. However, there are situations that can occur within the household to restrict this airflow, such as ductwork design, unit location, zoning and dirty filters, to name just a few. Think of variable-speed technology as your insurance for home comfort the way you prefer it. Variable-speed technology ensures that your home receives the amount of air required to keep you and your family comfortable. Variable-speed motors have intelligent technology that monitor incoming data from the blower and adjust accordingly so you can feel confident that your system is working to keep you comfortable.

Having the technology of variable speed in your furnace offers many benefits:

Electrical efficiency: Variable-speed motors can actually save you money on your energy bills as they consume less electricity than standard motors.

Cooling efficiency: Variable-speed technology also means you will gain air conditioning efficiency or SEER.

Zoning: Variable-speed furnaces are excellent for zoning, where you control the conditioning of your home. Zoning allows you to customize your comfort in different areas or zones in your home and control your energy bills.

Air quality: A variable-speed motor combined with a humidistat allows you to control the humidity in your home. Humidity plays a big role not only in the comfort of your home, but also in its air quality. The relative humidity in your home should be between 30 and 60 percent. This range is most ideal to minimize growth of biological pollutants such as mold and mildew. The consistent airflow of the variable-speed motor also helps to improve air filtration.

Your local Service Experts sales and service center can show you additional benefits of owning a variable-speed system.

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What is two-stage heating (or a two-stage furnace)?

Thanks to the innovation of two-stage heating, it is possible for your home to be cozier than ever while saving you money on your energy bill in the process. Two-stage heating can be a tremendous help when looking for that just-right temperature during the cold winter months.

Traditional single-stage furnaces are designed to heat your home and keep you warm during the coldest weather in your climate. Therefore, when they are operating, they are heating at their full capacity. Unlike those furnaces, two-stage furnaces are designed to operate like two separate furnaces, maintaining more consistent comfort levels throughout the home.

The first stage consists of the furnace running at about 68% of its heating capacity. A two-stage furnace will always start in the first stage and attempt to meet the heating demand. This reduced capacity is enough to warm a home on mild winter days. When temperatures drop, the furnace adjusts itself and enters the second stage to meet the demand for heat within the home. With two-stage heating, a homeowner has no need to keep adjusting the thermostat.

Two-stage heating has many advantages:

Consistent comfort: Thanks to two-stage technology, the temperature inside your home should vary only a couple of degrees versus the larger temperature swings that are common with traditional furnaces.

Quiet comfort: Because a two-stage furnace starts in its first stage, when the amount of heat required is lower, and runs in this stage about 80 percent of the time, it greatly reduces the noise associated with furnaces that turn on and run full blast. Two-stage technology means quiet comfort.

Improved air filtration: A two-stage furnace provides more consistent airflow and with more consistent airflow comes improved air filtration, which means you'll breathe easier with two-stage heating.

Efficient operation: Because the furnace spends the majority of its time operating in its lower-capacity first stage, it burns less fuel than a traditional furnace that always runs at full capacity and then shuts off when the heating demand has been met.

Although you can't see the air and temperature within your home, you can certainly feel them. A two-stage furnace can provide preferred comfort within your home despite the changes in weather outside your home.

Your local Service Experts sales and service center can show you additional benefits of owning a two-stage system.

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When is the best time to replace a furnace?
There are many factors involved in determining the best time to replace a furnace, such as its current operating efficiency, condition, make, model and the age of the furnace. A very basic rule-of-thumb is that every 10 years or so, efficiencies in furnace energy consumption for home heating equipment advance enough to warrant the utility savings a new furnace can bring. This is a somewhat broad generalization, many well-maintained furnaces may last much, much longer energy-efficient heating, and less quality models may only last a few years.

The only way to really know the best time to replace your furnace is to have an HVAC inspection and energy analysis performed on your heating and cooling system. We offer this service as part of any appointment, but you might get the most use of the information for free by scheduling a Comfort Advisor to perform the analysis and discuss the furnace options available to you. Every home and person is different, a Comfort Adviser can help you find solutions customized for your specific home and family’s comfort needs.
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When should furnace filters be changed?
Many factors can cause air filters to become dirty at various intervals, so it depends on your location. For instance, homes near factories or airports may accumulate dust or debris more often. Furnace filters should generally be changed when there is visible dirt accumulated on the filter. Usually, a regular filter should be changed at least every season, but in many cases that is not enough. Check with your HVAC company on the appropriate time to regularly change filters in your area. Airflow is restricted by dirty filters and this can cause increasing loss of heating and air conditioning efficiency, and may even damage the HVAC equipment.
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Will my new furnace work differently than my old one?

A new furnace may not operate exactly the same as an older one. When you install a new indoor comfort system in your home, you'll probably notice it operates differently than your old system. Radical changes have taken place in the technology of the comfort industry in recent years. These changes will affect how your system operates and may also affect what you notice about your system.

Higher efficiencies in furnaces and air conditioners have become increasingly important over the past few years. Consumers, government agencies and manufacturers all see higher efficiency as a way to conserve our natural resources while reducing consumer energy costs. Today, furnaces are designed with high efficiency in mind.

To achieve higher efficiencies, new gas furnaces must move more air over the heat exchanger than older furnaces so that as much heat as possible can be sent throughout the house.

The air that comes out of your furnace registers may not seem as warm as the air was from your old furnace, but it will heat your house just as well. In fact, better airflow can improve overall comfort by reducing air temperature differences from the ceiling to the floor throughout your entire home.

Modern furnaces are designed to handle high-efficiency air conditioners and must have blowers that are efficient yet powerful enough to accommodate the add-on cooling. Since cold air is much heavier than warm air, your system needs an extra boost from the blower to get cool air throughout your home to provide you with efficient total comfort during the summer.

Higher airflow required for cooling operation could contribute to unfamiliar sound levels when your new furnace is operating because older homes' air duct systems were designed for heating only. Service Experts offers products with multiple speed settings to allow for the varying air needs of both heating and cooling cycles.

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