Changing Your Furnace Filter

Part of responsible homeownership includes, of course, regular home maintenance. And there are some tasks that, if deferred, can lead to a home system that’s inefficient and overworked, which can result in problems and expenses. One such task is changing the filter of the home’s HVAC system. It’s simple and inexpensive, and taking care of it at least every three months can mean the difference between optimum comfort and avoidable repairs.

What Can Go Wrong

Most homes have some sort of furnace or heat pump, and many of those homes (especially newer ones) have combined heating, ventilation and air-conditioning or HVAC systems. Each type uses some type of air filter or screen to prevent larger airborne particles (up to 40 microns) from entering the system and clogging sensitive machinery. A system that has a dirty filter can suffer from pressure drop, which can lead to reduced air flow, or “blow-out,” resulting in no air infiltration at all. Any of these conditions can cause the system to work harder to keep the home warm or cool (depending on the season and the setting). And any mechanical component that has to work harder to run efficiently puts undue stress on the whole system, which can lead to premature failure, resulting in repair or replacement.

Also, a dirty filter that’s exposed to condensation can become damp, which can lead to mold growth that can be spread throughout the home by the HVAC system. This can lead to serious health consequences, not to mention a compromised unit that will likely require servicing and may require replacement, depending on the severity of the moisture problem.

Types of Filters

Most HVAC and furnace filters are disposable, made of biodegradable paper or similar media, and shaped in cells, screens or fins designed to trap as much airborne debris as possible. Filters can typically be purchased in economical multi-packs, and there are many types that will fit different models of furnace/HVAC units. It’s important to use the appropriate filter for your unit; using the wrong filter that doesn’t fit the unit properly can create the same types of problems as having a dirty filter. Your HVAC installer can show you where the filter goes and how to remove the old one and install a new one. Your unit may also have an affixed label with directions for easy filter replacement.

How Often?

Your HVAC or furnace technician should service your unit once a year. Because a furnace/HVAC unit contains moving parts, it’s important that belts are not cracked and dry, ventilation ductwork is not gapped, cracked or rusted, and components, such as coils and fans, are clog-free and adequately lubricated for unimpeded operation. This sort of evaluation is best left to the professional, unless the homeowner has had the appropriate training.

The filter of the unit, especially if it’s an HVAC unit that will tend to get nearly year-round use, should be changed by the homeowner at least every three months, but possibly more often.

Check your filter’s condition and change it once a month if:

• You run your unit six months a year to year-round.
• You have pets. Pet dander can become airborne and circulate through the home’s ventilation system just as typical household dust does.
• You have a large family. More activity means more household dust, dirt and debris.
• You smoke indoors.
• You or someone in your household suffers from allergies or a respiratory condition.
• You live in a particularly windy area or experience high winds for extended periods, especially if there are no nearby shrubs or trees to provide a natural windbreak.
• You live in an area prone to or having recently experienced any wildfires. Airborne ash outdoors will eventually find its way indoors
• You have a fireplace that you occasionally use.
• You live on a working farm or ranch. Dust and dirt that gets kicked up by outdoor work activity and/or large animals can be pulled into the home’s ventilation system, especially through open windows.
• You have a large garden. Depending on its size and how often you work it, tilling soil, planting, pulling weeds, using herbicides and pesticides, and even watering mean that dirt, chemicals and condensation can be pulled into your home’s ventilation system.
• There is construction taking place around or near the home. You may be installing a new roof or a pool, or perhaps a neighbor is building a home or addition. Even if the activity is only temporary, dust and debris from worksites adjacent to or near the home can be sucked into the home’s ventilation system, and this increased activity can tax your HVAC system.

Change the filter immediately if:

• The filter is damaged. Whether it happened inside the packaging or while being installed, a damaged filter that has bent fins, collapsed cells or holes will not work as well as an undamaged filter, especially if it allows system air to bypass the filter at any point. 
• The filter is damp. A filter affected by moisture intrusion, system condensation, or even high indoor humidity can quickly become moldy and spread airborne mold spores throughout the home via the ventilation system. 
• There is evidence of microbial growth or mold on the filter. Mold spores already infiltrating the home via the HVAC system are not only bad for the unit itself, but they can pose a health hazard for the family, ranging from an irritated respiratory system to a serious allergic reaction. The musty smell produced by a moldy HVAC filter is also unpleasant and may take a while to completely eradicate from inside the home. If you discover that you have moldy air filter, it’s important to have the cause investigated further. An InterNACHI inspector or HVAC technician can help determine the problem so that it doesn’t recur.

Tips on Changing the Filter

• Turn off the unit before replacing the filter.
• Use the right filter for your unit and make sure it’s not damaged out of the package.
• Follow the directions for your unit to make sure you’re installing the filter properly. For example, many filters use different colors for the front and back (or upstream and downstream flow) so that they’re not installed backwards.
• Make sure there aren’t any gaps around the filter frame. If this is the case, you may have the wrong size filter, or the filter itself may be defective or damaged.
• Use a rag to clean up any residual dust before and after you replace the filter.
• Securely replace any levers, gaskets and/or seals.
• Turn the unit on and observe it while it’s operating to make sure the filter stays in place.
• Note the date of filter replacement in a convenient location for the next time you inspect it. A filter that becomes dirty enough to change within a short period of time may indicate a problem with the unit or ventilation system, so monitoring how often the filter requires changing is important information for your technician to have.

Call a technician for servicing if:

• Your unit fails to turn back on.
• The fan is slow or makes excessive noise, or the fins are bent.
• The coils are excessively dusty or clogged.
• You notice moisture intrusion from an unknown source anywhere in the system.

Homeowners who take care of the easy task of changing their HVAC filter can help prevent system downtime and avoidable expenses, as well as keep their families living and breathing comfortably. Your InterNACHI home inspector can provide more useful tips and reminders during your annual home maintenance inspection.

From Homeowner Maintenance: Changing the HVAC Filter - InterNACHI http://www.nachi.org/change-hvac-filter.htm#ixzz2iCn45tY6

Aluminum Wiring

Between approximately 1965 and 1973, single-strand aluminum wiring was sometimes substituted for copper branch-circuit wiring in residential electrical systems due to the sudden escalating price of copper. After a decade of use by homeowners and electricians, inherent weaknesses were discovered in the metal that lead to its disuse as a branch wiring material. Although properly maintained aluminum wiring is acceptable, aluminum will generally become defective faster than copper due to certain qualities inherent in the metal. Neglected connections in outlets, switches and light fixtures containing aluminum wiring become increasingly dangerous over time. Poor connections cause wiring to overheat, creating a potential fire hazard. In addition, the presence of single-strand aluminum wiring may void a home’s insurance policies. Inspectors may instruct their clients to talk with their insurance agents about whether the presence of aluminum wiring in their home is a problem that requires changes to their policy language.

• On April, 28, 1974, two people were killed in a house fire in Hampton Bays, New York. Fire officials determined that the fire was caused by a faulty aluminum wire connection at an outlet.
• According to the Consumer Product Safety Commission (CPSC), "Homes wired with aluminum wire manufactured before 1972 ['old technology' aluminum wire] are 55 times more likely to have one or more connections reach "Fire Hazard Conditions" than is a home wired with copper."

Aluminum as a Metal

Aluminum possesses certain qualities that, compared with copper, make it an undesirable material as an electrical conductor. These qualities all lead to loose connections, where fire hazards become likely. These qualities are as follows:

• higher electrical resistance. Aluminum has a high resistance to electrical current flow, which means that, given the same amperage, aluminum conductors must be of a larger diameter than would be required by copper conductors.
• less ductile. Aluminum will fatigue and break down more readily when subjected to bending and other forms of abuse than copper, which is more ductile. Fatigue will cause the wire to break down internally and will increasingly resist electrical current, leading to a buildup of excessive heat.
• galvanic corrosion. In the presence of moisture, aluminum will undergo galvanic corrosion when it comes into contact with certain dissimilar metals.
• oxidation. Exposure to oxygen in the air causes deterioration to the outer surface of the wire. This process is called oxidation. Aluminum wire is more easily oxidized than copper wire, and the compound formed by this process – aluminum oxide – is less conductive than copper oxide. As time passes, oxidation can deteriorate connections and present a fire hazard. 
• greater malleability. Aluminum is soft and malleable, meaning it is highly sensitive to compression. After a screw has been over-tightened on aluminum wiring, for instance, the wire will continue to deform or “flow” even after the tightening has ceased. This deformation will create a loose connection and increase electrical resistance in that location.
• greater thermal expansion and contraction. Even more than copper, aluminum expands and contracts with changes in temperature. Over time, this process will cause connections between the wire and the device to degrade. For this reason, aluminum wires should never be inserted into the “stab,” “bayonet” or “push-in” type terminations found on the back of many light switches and outlets.
• excessive vibration. Electrical current vibrates as it passes through wiring. This vibration is more extreme in aluminum than it is in copper, and, as time passes, it can cause connections to loosen.

Identifying Aluminum Wiring

• Aluminum wires are the color of aluminum and are easily discernible from copper and other metals.
• Since the early 1970s, wiring-device binding terminals for use with aluminum wire have been marked CO/ALR, which stands for “copper/aluminum revised."
• Look for the word "aluminum" or the initials "AL" on the plastic wire jacket. Where wiring is visible, such as in the attic or electrical panel, inspectors can look for printed or embossed letters on the plastic wire jacket. Aluminum wire may have the word "aluminum," or a specific brand name, such as "Kaiser Aluminum," marked on the wire jacket. Where labels are hard to read, a light can be shined along the length of the wire.
• When was the house built? Homes built or expanded between 1965 and 1973 are more likely to have aluminum wiring than houses built before or after those years.

Options for Correction

Aluminum wiring should be evaluated by a qualified electrician who is experienced in evaluating and correcting aluminum wiring problems. Not all licensed electricians are properly trained to deal with defective aluminum wiring. The CPSC recommends the following two methods for correction for aluminum wiring:

• Rewire the home with copper wire. While this is the most effective method, rewiring is expensive and impractical, in most cases.
• Use copalum crimps. The crimp connector repair consists of attaching a piece of copper wire to the existing aluminum wire branch circuit with a specially designed metal sleeve and powered crimping tool. This special connector can be properly installed only with the matching AMP tool. An insulating sleeve is placed around the crimp connector to complete the repair. Although effective, they are expensive (typically around $50 per outlet, switch or light fixture).

Although not recommended by the CPSC as methods of permanent repair for defective aluminum wiring, the following methods may be considered:

• application of anti-oxidant paste. This method can be used for wires that are multi-stranded or wires that are too large to be effectively crimped.
• pigtailing. This method involves attaching a short piece of copper wire to the aluminum wire with a twist-on connector. the copper wire is connected to the switch, wall outlet or other termination device. This method is only effective if the connections between the aluminum wires and the copper pigtails are extremely reliable. Pigtailing with some types of connectors, even though Underwriters Laboratories might presently list them for the application, can lead to increasing the hazard. Also, beware that pigtailing will increase the number of connections, all of which must be maintained. Aluminum Wiring Repair (AWR), Inc., of Aurora, Colorado, advises that pigtailing can be useful as a temporary repair or in isolated applications, such as the installation of a ceiling fan.
• CO/ALR connections. According to the CPSC, these devices cannot be used for all parts of the wiring system, such as ceiling-mounted light fixtures or permanently wired appliances and, as such, CO/ALR connections cannot constitute a complete repair. Also, according to AWR, these connections often loosen over time.
• alumiconn. Although AWR believes this method may be an effective temporary fix, they are wary that it has little history, and that they are larger than copper crimps and are often incorrectly applied. 
• Replace certain failure-prone types of devices and connections with others that are more compatible with aluminum wire.
• Remove the ignitable materials from the vicinity of the connections.

Aluminum wiring should be identified and inspected. Having an home inspection is a great way to find out whether your house has aluminum wiring. For more information please contact us!