Hi Susan,
One of my properties with a furnace is managed by a 3rd party property manager. Utilities are in the tenant's name.
In my initial welcome letter to my new tenant, I clearly encouraged the tenant to change the filters as often as every month by mentioning the following in my letter:
- Changing furnace filters helps reduce the tenant's utility costs.
- Tenant is welcome to change them as often as every month to keep utility costs low.
- I (landlord) will gladly replenish the filters when tenant runs out.
And I leave 12 filters beside the furnace before the tenant moves in.
So far, it has worked well, and my tenant has been changing filters monthly.
I've also started the procedure of performing my own maintenance inspection at my professionally managed properties at least once every year, so I can check that the filters are being replaced and also replenish the filters at that time.
FYI, I don't buy the really cheap filters, but I don't use the expensive 3M ones, either. I use a cheaper pleated filter from Home Depot or Canadian Tire (whichever place has a sale).
Remember: it's YOUR furnace, not the tenants. We all know how much a new furnace costs, so you want that furnace to last as long as possible, so it's in your best interest to ensure that it's cared for. Some homeowners don't even remember to change them, so you can't always rely on tenants to change them as often as you wish.
Good luck.
George