Preventative Maintenance

I am sitting at the mechanics garage right now waiting for a transmission fluid change to be finished. This ‘once every 100,000 miles’ maintenance ticket is becoming less DIY friendly because of how infrequently it needs to be done. In fact, our car does not even have a transmission dipstick or drain plug!

There are other preventative maintenance jobs that are in reach of even the most novice DIYer, such as furnace filter changes.

Your homes furnace filter should be changed every 1-3 months.  Here you can see our 2 month old filter next to a brand new one.

I am replacing an expensive MERV 11 filter ($9.99) with a cheapo MERV 7 ($2.33).  The answer I cannot readily find is which filter is better for my HVAC equipment.

Your furnace and central AC is like a lung. It sucks air in and that air passes through a filter. It then blows air out to the rest of your house.  If the filter is too restrictive, the furnace has a hard time ‘breathing’ and the equipment has to work harder. If the filter is not restrictive enough, then dust and dirt can build up on the equipment and clog it up making it work harder. Somewhere there is a perfect balance, and it will be different for each setup.

The nice thing about the expensive filter, is that it lists the technical specs right on the filter. Details such as static pressure drop, initial resistance, and airflow are all printed right on the filter.

I could not find that information for the cheap filter anywhere.   The expensive filter has 17 pleats to the 12 of the cheap filter. In theory, more pleats in the same rectangle means a bigger surface area. A bigger surface area means more ways for air to pass through.  Without hard numbers however, it is impossible to draw any decisive conclusions.

Of course the decision on expensive or cheap filters might come down to health and comfort. The MERV 11 filters out mold spores and the MERV 7 does not.  Keeping your body healthy might be the most important preventative maintenance you do!

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