Question: Pardon my ignorance…Thank goodness for folks like you!! I just purchased a top-of-the-line Trane unit.  I did not realize there are so many different types of filters. In my old unit, I used cheap fibreglass filters - not knowing that was a mistake (however my old Trane ran for 17 years +, with less than $300 in repairs that entire time-period, and no annual maintenance.) With this new unit, what should I use, or let me ask like this… Is a Nordic Pure or 3M Filtrete Micro-Particle Reduction Filter 700 alright to use? Both filters are one inch thick but the Filtrete filter doesn’t have a MERV rating on it.

Let me start by saying that in my opinion Trane is one of the top residential air conditioner and heat pump manufacturers. Their equipment performs well and usually operates trouble free. Although, I would consider 17 years of trouble free service with less than $300 in repairs to be exceptional.

The only thing I consider to be more important than a quality product is the quality of the installation. This is far more important. The best equipment installed inadequately will not perform as well as equipment of lower quality that is installed properly.

What is the difference between fibreglass filters and Nordic Pure or Filtrete filters?

Fibreglass filters were originally designed to prevent things from getting into your furnace or air conditioning system and causing problems with fans, pulleys and other components. They were not designed to improve indoor air quality.

Nordic Pure and Filtrete filters do both. They improve indoor air quality by attracting and capturing allergy causing micro particles, and help keep your equipment clean. Air in your home is continually re-circulated through these filters, and is cleaned each it passes through the filter.

What does electrostatic mean?

These pleated electrostatic filters are made with positive and negative charged media fibres. Particles in the air passing through the filter will be either positively or negatively charged and result in the charged particles sticking to the filter.

Are Nordic Pure pleated air filters antimicrobial?

From their website:

How often do I need to change pleated air filters?

These filters should be changed every three months. However, the effectiveness and life of the filter will vary depending on the individual conditions in your home. A dirty duct system, construction, pets, smokers and running the fan continuously are some of the things that can shorten the life of your filter.

In these cases, the filter should be checked more frequently and changed if needed. For the untrained eye it can be difficult to determine if the filter is dirty enough to change or not, an air filter change indicator installed on your air handler can help with this.

Do I have to worry about restricted air flow with these filters?

These pleated air filters are designed to operate in most residential furnaces and air conditioning systems. If the filter remains in use longer than three months, it may begin to restrict airflow or cause operating problems.

The best furnace filters to use in your home are the ones that provide the results that you want. When trying to choose a filter to use it is important to consider what you objectives are. Just because a filter is the most efficient doesn’t make it the best furnace filter. It just makes it the best choice for a person who has allergies or other health concerns. There are many variables to consider when selecting a replacement air filter for your furnace or air conditioner. We have created a list of the most common types of filters used by home owners. These are not the only furnace filters available but they are among the most common types.

Pleated furnace filters

• Pleated air filters are the most common filters used in residential and commercial HVAC equipment. They are probably the easiest to find at your local hardware store although better pricing is available online.
• These filters are available in a wide range of efficiencies from about MERV 5 to MERV 12. The higher the MERV rating is the more efficient the filter is. This also means that it may need to be changed more often because the more dust it collects the faster it begins to have a negative impact on air flow.
• These filters are very easy to maintain. Simply change them every two to four months or when recommended by the manufacturer.
• One of the things that make them so common and popular is that they are available in custom sizes.

Electrostatic furnace filters

• Some electrostatic furnace filters are very high quality and will last for many years. Wash them once a month and they are as good as new.
• Electrostatic air filers cost more to purchase but they eliminate the monthly expense of buying disposable filters. Pay $50 to $100 up front for an electrostatic air filter or $5 to $10 or more each time you change your disposable air filter. This adds up to decent savings over a 10 year period. If you replace a $5 filter 4 times a year it adds up to $200 dollars in 10 years. A $10 disposable air filter will cost $400 in 10 years. It’s the little things that save you money.
• If you don’t like doing maintenance tasks then these filters are not for you. They must be maintained properly so they will remain effective.
• If Green living and the environment are important to you these filters are a good choice because they reduce landfill usage and they last for many years.

Media air filters (Pre-Cut Media Pads)

• Pre Cut media air filter pads are not used as often as the types listed above because they are not as popular with retail stores.
• If maintenance is not your thing and you sometimes forget to change your filters these may be for you. Media pads are much more forgiving. They have a much greater dust loading capacity than the other filters listed here. This means that when neglected it takes longer for it to negatively impact air flow and you can potentially avoid the decline in equipment operating efficiency that the other filters create when neglected.
• Carbon media pad inserts can be installed with these filters to help control odors.
• Pre cut pads are less expensive than most of the quality pleated air filters.

HEPA filters

• Hepa air filters are the most efficient air filters available.
• These filters utilize the pleated design of standard pleated air filters. The difference is in the number of pleats per inch of filter and the material used in the construction of the filters is much more efficient at stopping dust, pet dander, pollen and other airborne allergy causing contaminants that you may find in your house.
• Some brands, such as the Hepa-Pure, can be cleaned and used several times.
• True HEPA filters are 99.97% efficient and can remove particles as small a .3 microns in size.

Question: You made an excellent Web site.  It is very informative and easy to understand. It is loaded with good information and excellent charts.  I just wanted to let you know that you did a first rate job.

I was recently told by the company that installed the HVAC system in my now 3 year old home, that it would cost $1800 to change the filters in my four air handlers. There is one Lenox Pure Air, MERV 9, Media Filter, 17” X 26” X 4” (part # 75X74) in each unit.  The $1800 includes replacing the UV bulbs in each unit also, approximately 18, 10M13 UV lamps in total. Also there is a filter-size, corrugated screen cartridge, behind the lamp units that says “do not wash”. I don’t know what the replacement status of these are. The air handlers are Lennox CBX32MV(3)and CBX32M (1) units, a total of four.

I have three questions:

1. First, can I use a MERV 12 filter in the air handlers?
2. Second, do I really need to change the UV lamps?
3. Third does $1800 sound high for the job?

Without doing a lot of research, I would say $1800 is probably a fair price. You can get a box of 6 17 X 26 X 4 MERV 12 pleated air filters for about $151.00 at Nordic Pure.

I’m not sure about the cost of the new UV lamps but I would expect them to be fairly expensive. Add labour and mark-up of parts and it sounds about right. If price is important you may be able to do better with another contractor.

I think MERV 9 filters will do an adequate job especially when used with UV sterilizers. If you are finding there is too much dust then you could try MERV 12 filters. They should work OK but may need to be changed more often. Higher MERV filters have a greater impact on air flow and if duct systems are undersized could cause problems. Certainly worth a try though.

UV lamps do need to be changed. The light intensity of UV lamps declines over time and they don’t perform as well. You would have to check with the manufacturer for their recommendations but yearly replacements are typical.

Question: I have a Honeywell electronic furnace filter on my furnace. The power panel failed and the unit is very expensive to replace. However, I can install pleated air filters in place of the original electronic cells. The filter size is 20 X 25 X 4 inches thick. As a temporary measure, I have installed 3-1 inch thick MERV 8 air filters in parallel into the filter opening.  How does the MERV rating change when the filters are placed in parallel? Is what I have done a good solution? If not, what would you recommend that I do?

I would remove two of those 1 inch pleated air filters ASAP. Installing filters in this way has a very negative effect on air flow and reduces equipment efficiency greatly. Take a look at your air handler to see if there is a place to install a 1″ filter. Most air handlers come equipped with this filter rack.

Take a look at the pictures on this page “where is my furnace filter” if you are not sure where to look. If you can’t find a place to install a 1″ filter, you can get a 20 X25 X4 MERV 12 filter at NordicPure for a very reasonable price.

An air filter change indicator can potentially save you hundreds of dollars on replacement air filters and can even lead to reduced operating costs for your air conditioner, heat pump or furnace.

How is this possible?

• Change your furnace filter or air conditioner filter too often and it’s like throwing money away.
• Wait too long between filter changes and equipment operating efficiency begins to decline.

How often should an air filter be changed?

Manufacturers often differ in their recommended filter change frequency. Some say every month, some say every other month and others recommend every three months and that’s only for 1 and 2 inch filters. If you use 4, 5 or 6 inch pleated air filters, recommendations vary from 3 months to a year.

Filters are expensive, especially the efficient varieties and the 4, 5 and 6 inch types so you don’t want to be changing them more often than absolutely necessary. It’s very difficult to know when a filter has reached the point where it is better to change it than to leave it in the system.

Manufacturers can’t really tell you because they can’t possibly know the conditions in every home, not to mention every geographic area. There are just too many variables to consider. If you follow a set schedule for your filter changes you are probably not getting the best value from your filters.

Leaving an air filter in your heating or air conditioning system too long costs money

If you don’t replace you air filter often enough it begins to impact air flow and causes equipment operating efficiency to decline. A decrease in operating efficiency translates to higher operating costs. This means higher energy bills and nobody wants that either.

If left in a system long enough, a dirty filter will cause air flow restriction and can cause evaporator coils to ice up, heat exchangers to crack, longer run times and other equipment troubles that may require a service technician.

So what’s the solution?

Installing an air filter change indicator eliminates the guessing from filter change schedules. You won’t be throwing money away by changing filters too often and you won’t be wasting money and dealing with the potential problems associated with leaving an air filter in too long.

More about air filter change indicators.