TL;DR
A furnace or air handler filter holds whatever was in the home's air for the last one to three months, and in a rental turnover it is one of the least likely items to have been changed. Swapping it costs a few dollars and about five minutes. There are usually five or six filters in a home worth handling on move in day, and together they change how the place feels within a week.
Why does a filter belong on a cleaning list?
Because a filter is a surface holding accumulated soil, exactly like a baseboard or a cabinet interior, except that the home's air passes through it continuously. Cleaning every surface in a house and leaving a loaded filter in place means recirculating the old home through the new one.
That is the whole argument. Filters are cleaning, not maintenance, at least on the day you move in.
The furnace or air handler filter comes first
This is the big one, and it is the one most commonly skipped at turnover.
Find it. It sits in one of three places: a slot on the return side of the furnace or air handler, behind a large return air grille on a wall or ceiling, or inside a dedicated filter cabinet.
Read the old filter. The size is printed on the cardboard frame in inches, as three numbers. Photograph it before you throw it away. If the printing is unreadable, measure the filter itself, not the opening.
Note the airflow arrow. Every filter has an arrow indicating direction of airflow, which points toward the furnace or air handler. Installing one backward reduces performance. Mark the direction on the duct so the next change is easier.
Change it, then write the date on the new filter. A marker on the cardboard edge is the simplest tracking system that exists.
On filter type, a mid range pleated filter is a reasonable default. Very restrictive filters can reduce airflow in some systems, so if the system documentation specifies a range, follow that. Source: HVAC equipment manufacturer maintenance documentation.
The range hood filter
The second filter that matters most, and one almost nobody thinks of as a filter.
Under most range hoods sits a removable metal mesh or baffle panel. In a home with unknown history, it is usually saturated with cooking grease. It affects both odor and how quickly grease redeposits on your new kitchen.
Pop it out, soak it in hot water with dish soap, scrub gently, rinse, and dry completely before reinstalling. If the hood is a recirculating type, it may also have a charcoal filter behind the mesh, which is replaced rather than washed.
This item is a large part of clearing previous owner smells, because a greasy hood filter keeps releasing odor every time the fan runs.
The rest of the filters in a typical home
- Dryer lint trap and its housing. Clean the screen, then vacuum the slot it sits in, which collects lint the screen misses. Check the exterior vent flap opens freely.
- Dishwasher filter. A removable cylinder or flat screen at the bottom of the tub. Rinse it under running water. This is a frequent source of a dishwasher smell.
- Washing machine. Front loaders often have a drain pump filter behind a small door at the bottom front. Put a towel down and expect water.
- Refrigerator water filter. If the unit dispenses water or makes ice, the filter has a service life and you do not know when it was last changed.
- Vacuum filters. Cleaning a vacuum filter covers the types.
- Bathroom exhaust fan. Not technically a filter, but the cover collects dust. Remove it, wash it, vacuum the housing, and confirm the fan moves air.
That is five or six items, none taking more than ten minutes. They belong on a move in cleaning checklist alongside the surfaces.
What a fresh filter does and does not do
Worth being straightforward about this.
A clean filter captures particles from air passing through the system, protects the equipment from dust, and helps the system run as designed. Combined with cleaning and ventilation, it contributes to a home that feels less like someone else's.
A filter does not remove odor from surfaces, does not solve a moisture problem, does not address mold, and does not treat, prevent, or cure any medical condition. If someone in the household has a specific respiratory concern, that is a question for their doctor, not for a filter aisle.
If the home has visible mold growth, persistent mustiness, or a known water intrusion history, remediation is a separate trade and should be handled by a remediation professional rather than by changing a filter and hoping.
What about duct cleaning?
A reasonable question in a home with unknown history, and the honest answer is that it depends on what you find.
Look at the return air grille and a couple of supply registers. Vacuum the covers and shine a light in. Heavy visible debris, evidence of pests, or construction dust justifies having a duct professional assess it. If they look normal, changing the filter and cleaning the registers is usually enough. Cleaning air ducts and vents covers where that line falls.
For renters, one extra step
Check the lease. Filter changes are commonly the tenant's responsibility, sometimes the landlord's, and occasionally the subject of a specific clause.
Either way, change it on day one. If it is your responsibility, you have started fresh with a known date. If it is not, note the condition in writing and ask when it was last changed, which is a fair question and a useful record.
A simple ongoing schedule
Once the move in swap is done, set the rhythm: the furnace filter every one to three months and sooner with pets, the range hood mesh monthly, the dryer lint screen every load with a quarterly housing vacuum, the dishwasher filter monthly, the refrigerator water filter per the manufacturer, and the bathroom fan cover quarterly.
Set a recurring reminder the same day. The whole point of doing this at move in, alongside what to clean first in a new home, is that you get a known starting date for everything at once.
FAQ
Should I change the furnace filter when I move in?
Yes, on day one. A filter holds the last one to three months of the home's air, and it is one of the least likely items to have been changed during a turnover. It costs a few dollars and takes about five minutes.
How do I know what size furnace filter I need?
The size is printed on the cardboard frame of the existing filter as three numbers in inches. Photograph it before discarding it. If the printing is unreadable, measure the old filter itself rather than the opening, since the slot is slightly larger.
Which way does the arrow on an air filter point?
Toward the furnace or air handler, in the direction air flows through the system. Installing a filter backward reduces its performance. Marking the correct direction on the duct with a pen makes future changes quicker.
What filters are in a house besides the furnace filter?
The range hood mesh, the dryer lint screen and its housing, the dishwasher filter, the refrigerator water filter, a front load washer drain pump filter, and any vacuum or air purifier media. The bathroom exhaust fan cover is worth cleaning at the same time.
Does changing filters help with a previous owner smell?
It helps, especially the furnace filter and the range hood mesh, since both hold odor and keep releasing it when air moves through them. It is one part of the job, alongside cleaning soft surfaces, refilling dry drain traps, and ventilating the home.
The whole-house equivalent of this routine is covered by house cleaning services.
Filters are the smallest job on any move in list and one of the few that keeps paying out every day afterward. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.