Question: I have a Trion Air Bear media filter installed close to my furnace in my basement.  I also have two Newfoundland dogs who shed like fiends.

I have found the expensive Trion media filters clog quickly (well before a year, more like a month) with fur. I wonder if it would make sense to install return air grille filters with cheap fibreglass filters as a sort of pre-filter to extend the life of my Trion Air Bear media filters?  It seems like this could help prevent pet fur from building up in my ducts. Do you see any problems with this?

Your Trion Air Bear filter probably has a MERV 11 rating. Furnace filters and air conditioner filters with high MERV ratings already restrict air flow so adding another filter has an even greater impact.

I typically don’t recommend using fibreglass filters because they do such a poor job and I am always cautious about using two media air filters together.

However, every filter has its use and fibreglass panel filters are great for your problem. Be very careful not to let them get too dirty because having two filters in a system can cause a number of problems. I would recommend changing them monthly at least and maybe more.

I would also recommend that you check the MERV rating of your Trion Air Bear filter. The rating should be marked on it. If the MERV rating is higher than 8 I would recommend changing it to a filter with a MERV 8 rating. These have less impact on air flow than the higher MERV filters and will still do an adequate job.

Read the articles below for more information about some of the potential problems that can be created when restriction air flow.

When to change your air conditioner filter
How often do you need to change your air conditioner filter?

Question: I have a UV air cleaner in my home.  What MERV rating air filter do I need to use?  Would it be beneficial to use a MERV 11 filter or would a MERV 8 work?  I change my filter every month when it’s running but I will go for 3 months.  I have changed the filter at different times and it seemed (by the naked eye) clean.  Should I let it go longer or still go on the same maintenance cycles?

A UV air cleaner doesn’t eliminate the need for efficient air conditioner filters.  The UV air cleaner will help to kill mold spores, bacteria and viruses but they don’t actually filter the air, they only purify it.  You still require an efficient air filter to remove dust particles from the air.

A MERV 8 filter is adequate for most homes unless you want to maintain the best air quality possible.  A MERV 11 filter is very efficient and will do a good job.

How often should you change your filter

It is best to follow manufacturer recommendations for filter change frequency.  They know their products and can better guide you in this area.

Personally, I think changing furnace filters and air conditioner filters every month is more often than necessary.  I usually change filters every 3 months in commercial buildings.  If every 3 months is good enough for these applications, where there is more dust, then it should be fine for residential applications.

One thing to consider is that filters used in commercial applications usually aren’t as efficient as the ones used in residential applications so they don’t become dirty as quickly.

If you can tell by looking at your furnace filter or air conditioner filter that it is not getting dirty then it probably doesn’t need to be changed for a while.

Other articles about how often to change air filters

When To Change Your Air Conditioner Filter

Every house is different and there are many factors that determine how often your heating and air conditioning filters should be replaced. If you wait too long operating efficiency begins to decline, as efficiency drops operating costs increase. Changing your air filter more often than necessary is like throwing money away.

Question: With regard to pleated air conditioner filters do you think I can go with a MERV 6 filter or do you think I will be better served going with a MERV 8 filter?

A MERV 8 filter will perform better than a MERV 6 filter but the difference will be minimal. If you are not too concerned about dust a MERV 6 filter will do a good enough job. If you are looking for a big improvement in dust control you may want to try a MERV 11 or 12 pleated filter.

Pleated filters in the MERV 5 to 8 range will stop particles of 3 to 10 microns such as some mold spores, fibers, dust mites, some bacteria and fiberglass among other things.

MERV 9 to 12 filters stop particles of 1 to 3 microns such as smoke, bacteria, spray, fumes, coal dust and auto emissions and many other things.