A Rather anal-retentive question re frequency of replacing furnace filters in CO condo

[Judy Mitchell]

Hello BP Community,

Here I am reaching out to you again.

As a native Coloradan residing in Bangkok for 11+ years I am afraid I am out of touch with how to maintain furnaces.  I believe I misinformed my tenants that 1x per year is adequate. I am now thinking 2x per cold season is actually the correct amount, based on my assumption that a person in the Denver-Metro area is likely only needing their furnace from Nov - May (unless they are super-wimpy like I now am, with tropical blood).  So in a 6-month period of usage 2 filters would be sufficient.  

What do you say, BPers?  I am refining my Lease Agreement requirement with my excellent tenants of my so far only rental unit, in anticipation of a pending 2nd purchase soon.  I just want to give them appropriate guidance.

Details, details - hope this is not too boring of a request...

[Tyson Luthy]

Some people will say "every month" but we will replace filters when we do quarterly inspections.

In my experience most tenants won't replace filters, even if it's in the lease. In that case you could serve a lease violation, but still risk damage to your furnace. With the furnace being such a costly item, and filters being so cheap we choose to do that ourselves.