What can a whole-house air cleaner do, and what can't it?
EPA's advice on cleaner indoor air comes in an order: reduce or remove the sources, bring in clean outdoor air with ventilation, and use filtration as a supplement to those two. Filtration is the part that runs through your furnace, and it's worth doing well. It also has limits you should know before spending money:
- It only cleans air the blower moves. With the thermostat fan on Auto, that's only while the furnace or AC is running.
- Filters catch particles: dust, pollen, dander, mold spores and smoke. Gases and odors mostly pass through unless the filter carries activated carbon, which is what EPA points to for gases.
- Dust already settled into carpet and upholstery stays there until something kicks it up.
We won't promise health results. What we will do is match the equipment to the problem you describe, and make sure your system can still breathe once it's in.
Start with the filter: MERV ratings and media cabinets
MERV, the Minimum Efficiency Reporting Value, rates how well a filter catches particles between 0.3 and 10 microns in a standard lab test. EPA recommends at least MERV 13, or as high as your system will accommodate, and a MERV 13 filter has to remove at least half of the smallest particles in that test. EPA adds that most furnaces can take MERV 13 without equipment problems as long as the filter is changed often.
The catch in many Minnesota basements is the 1-inch slot the furnace came with. A thin MERV 13 crams dense media into a panel an inch deep, and on a system with a single small return, or returns made by nailing sheet metal across the floor joists, it can starve the blower. The furnace runs hot and trips its high-limit switch; the AC coil runs cold enough to ice on a humid July day. Move that rating into a 4- or 5-inch media cabinet mounted in the return and the pleats get deep enough to multiply the surface area, so air passes more easily and the filter lasts for months. For most houses, that cabinet is where we'd start.
Air that goes around a filter never gets cleaned. An open filter slot, an undersized filter or a leaky return duct pulling basement air into the blower can undo a good rating, and sealing the returns can matter as much as the filter. Our MERV guide shows what each rating catches, and Aprilaire 5000 vs 2000 compares two common cabinets.
Air cleaning options compared
| Option | What it does | What it doesn't do | Upkeep |
|---|---|---|---|
| 1-inch pleated filter | Protects the blower; higher ratings catch finer particles | Hold much before it starts restricting airflow | Check monthly in heavy use |
| Media cabinet, MERV 13 to 16 | Deep pleats catch fine particles with less restriction than a thin filter | Remove gases or odors, unless you choose a carbon version | New filter every several months to a year |
| Electronic, collector-cell type | Charges particles and collects them on metal plates | Keep up once the plates load; some models may emit ozone | Wash the cells on the maker's schedule |
| Polarized media | A powered field helps a disposable fiber pad hold fine particles | Do more than plain media if the power is off | New pad every few months |
| Ionizer or bipolar ionization | Releases charged ions into the air stream | Come with much research outside lab conditions, per EPA | Per the maker; look for UL 2998 |
| Coil UV lamp | Keeps mold and slime off the AC coil and drain pan | Catch any dust, pollen or dander | New lamp about once a year |
| UV plus catalyst (PCO) | Aimed at odors and chemical vapors, per its makers | Replace filtration; EPA says research hasn't shown PCO removes gases well in portable home units | Lamp, cartridge and filter on the maker's schedule |
Electronic, polarized and ionizing cleaners
All of these use electricity to make particles easier to catch, and they tend to be sold with big percentages. What each one is:
Collector-cell electronic air cleaners (electrostatic precipitators) charge passing particles in a high-voltage section and catch them on oppositely charged metal plates. There's no filter to buy, but the cells come out for washing on the maker's schedule, and a loaded cell catches less. Honeywell Home's F300 is one example.
Polarized-media cleaners run on a 24-volt connection that powers a charged field across a disposable fiber pad. Fine particles are drawn to the polarized fibers, and the pad gets replaced every few months. Think of it as a filter with help; without power, it's only a filter.
Ionizer-assisted media, such as the Aprilaire Model 5000, puts ionizer wires ahead of a deep filter to charge incoming particles, so the media grabs more of them. By Aprilaire's own numbers, its passive MERV 13 and MERV 16 cabinets now make similar claims without the wires.
Ionizers and bipolar ionization release ions into the air stream. EPA calls bipolar ionization an emerging technology with little research outside lab conditions, says it can generate ozone and other potentially harmful by-products unless specific precautions are taken, and recommends a device certified to UL 2998 if you use one.
Ask for the ozone documentation on anything that plugs in. We service all of these, including Honeywell Home and Aprilaire units, but for most houses we'd put the money into a deep media cabinet first.
UV lights: a coil cleaner, not an air cleaner
A UV-C lamp mounted through the plenum and aimed at the evaporator coil keeps mold and bacterial slime from establishing on the coil and drain pan, which stay wet through the cooling season. Growth there is what gives some houses a musty whiff each time the AC starts; see AC that smells like dirty socks. A lamp placed in the moving air stream is a weaker proposition, since each bit of air passes it in a moment.
Before adding a lamp, clear the condensate drain and clean the coil; the lamp keeps a clean coil clean. Choose a lamp sold as ozone-free, aim it at the coil rather than at wiring and plastic parts that UV-C degrades, and use a panel switch so it shuts off when someone opens the cabinet. Lamps lose strength before they burn out, so replace them on schedule. Our UV light post covers the trade-offs, and Lennox PureAir is an example of a UV-plus-catalyst system built for odors.
Minnesota air: smoke, sealed-up winters and old returns
- Wildfire smoke. Smoke from Canadian fires has drifted over Minnesota in recent summers. It's made of fine particles, so this is where a MERV 13 filter and a blower set to On pay off.
- Six sealed-up months. With the house closed from late fall to spring, household dust, dander and cooking particles have nowhere to go but the filter. More blower run time means more air through the filter, at the cost of some electricity.
- Black filters. On still winter nights, fireplace and wood stove smoke can work its way indoors, and a filter that turns black points to soot. Rule out the furnace, water heater and boiler first; see why a furnace filter turns black.
- Old returns. Many older houses were built with one central return, so they're short of return air before anyone adds a filter. Static pressure tells us whether a cabinet fits as-is or the return needs work first.
- Radiator houses. Boiler-heated homes in Minneapolis and Saint Paul have no ducted air to filter. A room-sized portable HEPA unit is the practical choice there; see boilers in Minneapolis for the heating side.
How does an air cleaner install work?
- Tell us the problem. Dust, allergies, smoke, odors or a musty AC each point to different equipment.
- We measure. Static pressure with your current filter, the size of the return and filter slot, and any gaps where air skips the filter.
- You get a written quote. Usually a media cabinet first, with powered options priced alongside if you want them.
- We install it. Cut the cabinet into the return beside the furnace and seal it, wire any powered equipment, and mount UV lamps with a panel switch.
- We test and label. We re-measure static pressure with the new filter installed, then write the filter size, rating and change date where you'll see it.
For equipment you already own, like an electronic cleaner with a dark power light or a burned-out UV lamp, a repair visit is a $79 trip charge, waived when you approve the repair.
How much does whole-house air cleaning cost?
Air cleaning equipment falls within our $350–$2,800 installed range, with a media cabinet or a UV lamp near the low end. You get a written flat-rate quote first, and installs carry our 2-year labor warranty on top of the manufacturer's parts warranty.
For national context, HomeGuide's whole-house air purifier guide gives these typical installed ranges: $400–$800 for a media cabinet ($100–$300 for the unit alone), $500–$2,000 for electronic air cleaners, $400–$800 for a UV light with $20–$70 bulbs replaced yearly, and $1,200–$3,000 for UV-plus-filter hybrid systems. Count filters, pads and lamps as part of the real cost.
If a new furnace is on the horizon, add the cabinet with it, since the return plenum gets rebuilt during a furnace replacement anyway; our furnace replacement cost guide covers that project. Every range we publish is listed on our pricing page, and the Minneapolis cost page covers heating and cooling equipment. Filters and UV lamps can be changed at a furnace or AC tune-up, from $129, and our indoor air quality page lists the other equipment we install.
What's included with air purification & filtration?
- Static pressure measured with your current filter, then again with the new one
- Return duct and filter slot checked for gaps that let air skip the filter
- Cabinet sized to the return opening and sealed into the duct
- Power wiring for electronic, polarized or UV equipment
- UV lamps aimed at the coil, shielded from wiring and plastic, with a panel safety switch
- Filter size, MERV rating and change schedule written on the cabinet
- 2-year labor warranty on installs, plus the manufacturer's parts warranty
Air Purification & Filtration questions
What MERV rating should my furnace filter be?
EPA recommends a filter rated at least MERV 13, or as high as your system will accommodate, and says most furnaces can take MERV 13 without equipment problems if the filter is replaced often. We still measure static pressure first on houses with one small return. The same MERV 13 rating in a 4- or 5-inch cabinet restricts less air than it does in a 1-inch filter.
Do electronic air cleaners make ozone?
Some can. EPA says air cleaners that use electrostatic precipitators, ionizers, UV lamps without adequate lamp coatings, or plasma may have the potential to emit ozone, a lung irritant. Ask for the manufacturer's ozone documentation before you buy, and for bipolar ionization, EPA recommends a device certified to UL 2998. Passive media cabinets aren't wired to anything, so they produce no ozone.
What's the difference between electronic and polarized-media air cleaners?
A collector-cell electronic air cleaner charges particles and catches them on metal plates you take out and wash. A polarized-media cleaner uses a small powered field to help a disposable fiber pad hold onto fine particles, and you replace the pad every few months. Both need power and more attention than a plain media cabinet, and both lose ground when their upkeep slips.
Will a UV light clean the air in my house?
Not much. A UV-C lamp shining on the wet AC coil and drain pan keeps mold and slime from getting established there, which is where it earns its keep. A lamp mounted in the moving air stream lights each bit of air for only a moment. UV catches no dust or pollen, so it's an add-on to a good filter, never a replacement for one.
Will a whole-house air cleaner help my allergies?
It can lower the pollen, dust mite debris and dander floating in the air that passes through it, which is the part a filter controls. It can't reach allergens settled in carpet and bedding, and it only cleans air while the blower runs. Running the fan continuously during pollen peaks sends more air through it. For the symptoms themselves, talk with your doctor; we can't promise medical results.
What should I do on wildfire smoke days?
Keep windows and doors shut, set the thermostat fan to On so air keeps passing through the filter, and check the filter after a smoky stretch, since smoke loads it quickly. Smoke is mostly fine particles, the hardest thing a furnace filter catches, and that's where MERV 13 earns its place: EPA notes it must remove at least half of the smallest particles in its test.
How often do filters, pads and lamps need changing?
Check a 1-inch pleated filter monthly while the furnace or AC runs a lot. Deep media filters last much longer; Aprilaire's MERV 13 cabinet filters carry a rating of up to 12 months. Polarized-media pads get replaced every few months, collector cells get washed on the maker's schedule, and most UV lamps are replaced about once a year, even while they still glow.
Sources
- HomeGuide cost guides (2026 editions) homeguide.com
- U.S. Environmental Protection Agency epa.gov