Furnace filter ratings are intended to provide a way to determine which filters are the best value. The problem is that you may need to know how well the furnace filter does with certain types of particles. This is especially true for people that have allergies or respiratory problems.

There is a simple concept with furnace filters that is directly related to the filter's performance. The tighter or denser media means smaller particles that are captured. Therefore, for people that need better air quality, you need a filter that will capture small particles.

Need to change your furnace filter? See the article 'Replacing a Furnace Filter', for more information.

Understanding Dust and Bacteria Particle Size

How big is big? Or better yet, how small is small? Particles are sized in microns. Furnace filter rating systems will be based on the size of particle (in microns) that can be captured.

A micron is 1/25,000th of an inch. So capturing a particle that is "1" micron in size is a pretty big deal. In fact, your best residential filters are designed to stop that size particle (see the rating information below).

Is one micron the smallest particle that you need to worry about. In a sense yes. There are smaller particles, but if you put a filter in that would stop them, your furnace would not run. It would not have the power required to pull the air through the filter. So the compromise is going after all the particles up to one micron in size.

If you get the one micron dust, you will also get all the dust and bacteria that are larger than that.

There are some rating systems for furnace filters. Not all rating systems are completely unbiased. In most cases they give you relative performance criteria.

Furnace Filter MERV Ratings

The MERV rating, (Minimum Efficiency Reporting Value) has a numbering range from 1 to 20. This rating system is sponsored by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and is intended for comparison use. This rating system has been in use since 1987. The generally accepted range for residential use would be between 5 and 12.

The MERV rating is based on tests that determine the filters ability to stop particles from .3 to 10 microns in size. This covers a wide range of mold, bacteria, pollen and dust. As a rule, the higher the number on the MERV rating, the better. You need to keep in mind that a filter that stops particles, also stops air flow. Filters with MERV ratings above 12 are generally for commercial environments where the hvac equipment can handle the resistance.

For a residence, the types of furnace filters you choose should have a MERV rating between 5 and 12. The likely case would be between 7 - 9, a filter in this range provides decent protection without unduly restricting air flow.

For a graphical chart of what types of particles are stopped by a particular MERV rated filter, you can see this 'Particle Size Chart'.

MPR Rating System

Another system that you may run across is the MPR Rating System (Micro Particle Performance Rating). This system is sponsored by 3M for their Filtrete filters. It is a similar system to the MERV rating. It focuses on smaller particles. The MPR system uses numbers up to 1500, with the higher numbers being better.

The range for the MPR system that most homeowners would want to be in would be 800 to 1,250. The filters that it applies to are pleated disposable filters.

Other Filter Terms

Cheaper types of furnace filters may try to deceive you with numbers that have little meaning, but sound good. 'Arrestance' is a term that has to with a filter's ability to remove larger dust particles. Even a cheap filter may claim an 'Arrestance' rating of 80 - 90%. This may sound good, but it tells you nothing of how well it removes other contaminants. It is possible for a filter to have an Arrestance rating of 80% and have a MERV rating below 4.

Another term you may run across is 'Dust Spot Efficiency'. This measures the filter's ability to remove particles that can stain. Although it will not be an exact alignment, a filter with a higher MERV rating will also have a higher 'Dust Spot Efficiency' rating.

Your furnace plays an important part and should always be kept clean to avoid wasting fuel. A dirty furnace results to more use of fuel which in turn lowers its effectiveness. It is essential that the furnace be well-maintained and this means regular cleaning of the furnace.

It is also possible for some parts and controls to be damaged by a dirt and dust. A clean furnace will reduce wear and tear on all of the parts. A professional furnace company will reccommend that you have the furnace checked and cleaned twice a year. You can do the cleaning yourself and save some money.

Cleaning a Furnace Filter

To know how to clean your furnace, you need to be aware of the parts that need to be cleaned in order for the furnace to function efficiently. The first part one should clean is the filter. To access the filter, you will need to unscrew the access panel so that you will be able to reach the filter. After removing the filter, check for dirt and use tap water to clean it. If the dirt is not removable by water only, you can use a clean rag to clean the filter. You can also use a toothbrush to scrub out the dirt. Some filters have replacements. If this is the case, then replace the old filter with the new one. If you don’t have one, you can acquire it from a hardware store. Ensure that it is the same make and size as the previous one.

Cleaning the Blower Fan

The next part of your cleaning is the blower. The first thing you should make sure you have done is shut off all the power that runs the blower to avoid getting hurt. After this is done, remove the fan. This will require you to cut off the wires that connect the fan to the power source. It is essential that you remember which wires go to which places because you will need this information when returning the fan after cleaning it. You can use a toothbrush to clean the edges of the fan. If you have any clean rags, make them slightly damp and use them to clean off the remaining dirt. The blower usually has a belt, which you will need to check to ensure that it is not worn out. If it is worn out, replace it with a new one.

Cleaning the Heat Exchanger

Next step will be to clean the heat exchanger. This is made up of chambers, so you will need to clean each chamber separately. The dirt comes off by vacuuming, but since it is a small space and cannot fit a vacuum cleaner, you can put a vacuum hose and reduce the power. This will ensure any dirt has come off. If your furnace uses gas, remember to turn off the gas before you start cleaning the heat exchanger.


General Furnace Clean Up

After cleaning these parts, take a towel and make it a little bit damp, then use it to clean the rest of the parts. After all this is done, return all the parts accordingly. The furnace also contains a blower motor which should be kept lubricated at all times. Before lubricating, you should clean the motor using a damp rag.
While cleaning, make sure that you have the manual to see how to clean your furnace without damaging any of the parts. If you feel that you cannot be able to do it by yourself, you can always call a handy man.

The air ducts for your heating and cooling system have a tough job, and they are going to eventually become contaminated with dirt, mold and/or debris over time. Experts in the field recommend air duct cleaning bi=yearly, or every two years. Dingy and dirty air ducts can cause health concerns in your home and also represent other underlying issues.

As people learn about how to clean air ducts and keep them in tip top shape, it's important they be informed about the benefits and the purpose. If you're considering cleaning the air ducts for your heating and air conditioning system, then it's important you take the right steps in the right order.

Check For Mold

Mold can be one of the biggest problems in a home, and your air ducts are one place where it can be present. Mold assessment is absolutely necessary, and it is typically found in areas without adequate ventilation and where there is moisture.

Whether or not you can visibly see mold is one thing, but to determine its presence in your air ducts, an air sample must be undergo a laboratory analysis. Furthermore, insulation that has accumulated any mold will likely need to be replaced.

Debris Clogs

Are you witnessing any particles flying out of your air ducts? Even if this isn't the case, there could still be debris buildup in your air ducts, possibly even from rodents. Naturally, the buildup increases without cleaning the air ducts, and mold can come into play here as well. Mold grows on the debris, and as the debris builds up, it does indeed make its way into a home.

Air Duct Cleaning Estimate

That's right, you're not going to clean the air ducts on your own. Instead, you have a professional air duct cleaning company to pay you a visit and assess the situation, providing you with a no obligation estimate. If there is a mention of mold, request the laboratory analysis discussed in the previous section. You want to be present during the process so you can ensure everything is thoroughly checked, even the areas that are difficult to access.   

Environmental Protection Agency

The EPA cautions you to realize that if there indeed is a debris issue, or especially mold, then a remediation team must address what first caused the mold. Obviously, you're going to be dealing with more mold if you don't address the root cause.


Hiring The Right Company

Air duct cleaning is a very professional business niche utilizing top-notch equipment and requiring much experience and expertise. You're going to want to check testimonials of customers who also learned how to clean air ducts, and you're also going to want that solid estimate.

After an estimate is agreed upon, there needs to be a services contract in place. This contract is for your protection, detailing what services are going to be provided and the associated costs, and it will also highlight service guarantees the company offers you. Check over the contract, and then you're ready to let them render services.

Home heating repair can involve both fixing your equipment and maintaining. Heating and cooling is a big industry and you no doubt have numerous companies in your area that perform this type of service.

As a rule, not many homeowners attempt to work on heating and cooling systems. There are a few reasons for this. The first is that repairs are often needed immediately. If you furnace quits in the middle of winter, you often don't have time to figure out the problem on your own.

The other main problem is that parts are not readily available. Most local heating and cooling suppliers will not sell parts to individuals. This helps to protect the service industry that works on heating and cooling system.

There is also the safety issue. Heating and cooling repairmen are trained to work on furnaces and cooling systems. Some of the operations, such as charging a cooling system require special licenses. Since furnaces and cooling condensers use combustible fuels and/or substantial amounts of electricity, they are considered dangerous to work on.

With that said, there are some things a homeowner can do. Troubleshooting the problem first will save you having a serviceman come out when it is a simple problem. Some maintenance operations are not dangerous and the supplies can be obtained.

Home Heating Repair - Finding Help

Below you will find some common problems. There is a brief description and a link that will lead you to additional information. Our evaluation sections of the pages will help you to decide if you want to make the repair. The "What Can You Save?" and "How Hard Could It Be?"sections give you a quick overview of the repair. This will help you decide if it is in your best interest to make the repair yourself.

The "Check the Simple Things First" section will clue you in to easy fixes to check for. Many times quick fix will eliminate a problem without the aggravation of an involved repair. In an effort to warn you about what you are in for, there is the "What Can Go Wrong" section. Forewarned is forearmed as they say. Knowing what to watch out for is always helpful.

Home Heating Repair Topics

Replacing Furnace Filters

This is a common maintenance task that a homeowner can perform. Most types of filters should be replaced at the beginning of each new season. Some types of filters can be cleaned out and put back in.

Types of Furnace Filters

There are are several types of furnace filters. The size and type of particles that are captured can be important. This is especially true if someone in the home has allergies.

There are ratings for furnace filters that help you to determine what filter to get. Understanding the rating system can be a little confusing. How to understand them is covered in this series of articles.

types-of-furnace-filters-pic1Selecting a furnace filter will mean that you have to choose the type that you want. There are different types and ratings as to quality.

Furnace filters are rated by how well they trap particles in the air. The smaller and greater quantity of particles trapped, the better the filter, more or less.

There are different types of filters that you can get. They range from a disposable fiberglass filter to an electronic air cleaner. HEPA filters, the kind used in hospitals are the best at removing allergens and dust. However, the down side is that they restrict the air flow. Most residential furnaces are not equipped for the added resistance.

The question becomes, how concerned with allergens are you? You have to weigh that against cost for your furnace filter replacement project. When allergies are a problem, the extra cost is worth it.

There are some rating systems for furnace filters. The MERV rating (1 to 11, the higher the number the better)is sponsored by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) and is intended for comparison use.

The MPR system uses numbers up to 1250, with the higher numbers being better. Obviously, the better quality filters cost more. For a discussion on all the types of furnace filters, go to 'Types of Furnace Filters'. Find out what you need to know to make a good decision.

Types of Filters

Understanding furnace filter types is important if you have members of your family with health issues. Allergies and respiratory problems are adversely affected by poor air quality. Getting the right type of filter can improve the purity of the air in your home.

There is no question, better filters will cost more. Compared with trips to the doctor the added cost may be insignificant. Add to that the breathing discomfort that you or someone else in your home may experience, and cost pales in importance.

Do you understand the rating systems for furnace filters? See the article 'Understanding Furnace Filter Ratings' for more information. Do you need to know how to replace your furnace filter? See the article 'Furnace Filter Installation' for instructions.

Below you will find listings for some common furnace filter types. Cost needs to be weighed against  a families health concerns when selecting a filter.

Disposable Fiberglass Filters

These types of furnace filters are the least expensive ones to buy. You can probably find one that fits your furnace for a couple of dollars. You can buy a package of 12 for around $20. That sounds great. Well it is if cost is your only concern.

Unfortunately, the lower cost also means lower performance. These types of furnace filters will have MERV ratings between 1 and 4. The do an adequate job of removing dust from the air. For other things like bacteria, mold, pollen and small dust particles, they do a poor job. For homes that have people with allergies, they are not suitable.

Washable Electrostatic Filters

Electrostatic types of furnace filters are generally permanent and can be washed. They work by generating a positive charge that causes the dust to stick to the media. They are more expensive than disposable filters. However, considering that they are permanent the cost savings over the long haul can be significant. This type of furnace filter can be washed out with a hose, allowed to dry an put back in the furnace. The price range for a filter of this kind is between $50 and $200.

Electrostatic furnace filters do not have MERV ratings, because they are not a dry filter media. You will have to rely on information from the manufacturer to determine the performance of the filter.

There are some pleated disposable filters that also generate an electrostatic charge. This is perhaps getting the best of both worlds. These filters boast electrostatic charges for dust particles and quality pleated filter

Pleated Allergy Filters

Pleated allergy types of furnace filters are as the name implies, pleated. The pleating allow for better air flow while still filtering out small particles. These types of filters are good at removing common allergens and fine dust from the air.

This increased performance does not come without cost. This type of filter runs between $5 and $20 each. Most of them are good for three months before they need replacing. For homes that have people with allergies, they are a must.

These types of furnace filters will usually have MERV ratings of between 7 - 9 and MPR ratings of 600 - 1500. They are suitable for residential heating systems.

Electronic Air Cleaners

Electronic air cleaners are another piece of equipment that attaches to your heating and air conditioning system. The are fairly expensive, upwards of $1,500 installed. In addition they require regular maintenance and filter replacement.

The advantages are that they eliminate a higher percentage of contaminants from the air. For those with allergies or other health problems, this peace of mind may be worth the added expense. You have to have an hvac contractor install the system for you, since it has to be integrated with your duct work. Once installed, you can maintain it a replace the filters yourself.

Activated Carbon Filters

The addition of activated carbon to a furnace filter will help with odor control. Cooking, pet or smoke odors can be removed with activated carbon. The activated carbon is added to a pleated filter media that eliminates the other types of particles. These types of furnace filters are a little more expensive than the pleated allergy filters. When odors are a problem, you may not mind the extra expense.

Activated carbon filters can have a MERV rating, similar to other style filters. A rating of 8 should be possible. This is a good rating for a residential heating system.

HEPA Filters

HEPA stands for 'High Efficiency Particulate Air'. These are the best filters you can get for removing small contaminants. The problem is that they seriously restrict the flow of air in your ventilating system. Commercial buildings such as hospitals use this type of filter. They design the hvac systems for the reduced air flow.

There are some pleated allergy filters that claim to be HEPA rated. They may carry a MERV rating of 12. A filter like this will likely be suitable for a residential furnace. When in doubt, check with the manufacturer of your furnace or your furnace maintenance contractor.


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