Cost
Furnace humidifier pad replacement
The water panel in a ducted humidifier does the same job as a portable wick and lasts an order of magnitude longer. The reason is drainage, and it is the strongest argument for the ducted design.
By Scooter M. · Published · Updated
We earn a commission if you buy through the links on this page, at no extra cost to you. It does not change what we recommend or the order the picks appear in. Full disclosure. Prices checked October 12, 2026.
| # | Product | Best for | Gal/day | Price |
|---|---|---|---|---|
| 1 |  Aprilaire Model 700Top pickEighteen gallons a day against a stated 5,300 sq ft, cited to AHRI Guideline F. It is ducted, it needs installing, and it is the only sizing claim here with a standard behind it. | An actual whole house, sized against a standard | 18.0published · 5,328 sq ft | |
| 2 |  Levoit Superior 6000SSix gallons, evaporative, and a Dry Mode that dries the wicks between runs. The 3,000 sq ft claim needs five times the output its own run time implies. | Mist-free humidification with a drying cycle | 2.0implied · 592 sq ft | |
| 3 |  AIRCARE MA0800 Mini-ConsoleA 2.5-gallon evaporative console with three fan speeds, an adjustable humidistat and a MAF2 SuperWick. Its 2,600 sq ft claim is far beyond what its own tank and run time imply, so size it as a large room rather than a floor. | A plug-in console with its own humidistat | 1.7implied · 493 sq ft | Check price#ad |
A furnace humidifier's consumable goes by several names - water panel, evaporator pad, humidifier pad, media - and they all describe the same thing: a treated, high-surface-area panel that water runs across while furnace air blows through it.
It is the same idea as the wick in a portable humidifier. The interval is not remotely the same, and the gap is the most interesting number in whole-house humidification.
We earn a commission if you buy through the links on this page, at no extra cost to you. It does not change what we recommend or the order the picks appear in. Full disclosure. Prices checked October 12, 2026.
| # | Product | Best for | Gal/day | Price |
|---|---|---|---|---|
| 1 | Aprilaire Model 700Top pickEighteen gallons a day against a stated 5,300 sq ft, cited to AHRI Guideline F. It is ducted, it needs installing, and it is the only sizing claim here with a standard behind it. | An actual whole house, sized against a standard | 18.0published · 5,328 sq ft | |
| 2 | Levoit Superior 6000SSix gallons, evaporative, and a Dry Mode that dries the wicks between runs. The 3,000 sq ft claim needs five times the output its own run time implies. | Mist-free humidification with a drying cycle | 2.0implied · 592 sq ft | |
| 3 | AIRCARE MA0800 Mini-ConsoleA 2.5-gallon evaporative console with three fan speeds, an adjustable humidistat and a MAF2 SuperWick. Its 2,600 sq ft claim is far beyond what its own tank and run time imply, so size it as a large room rather than a floor. | A plug-in console with its own humidistat | 1.7implied · 493 sq ft | Check price#ad |
The interval, and the gap
| Unit | Consumable | Interval published | Per 182-day season |
|---|---|---|---|
| Aprilaire 700 (ducted) | Model 35 Water Panel | Annually | 1 |
| Aprilaire 500 (ducted) | Model 10 Water Panel | Annually | 1 |
| Aprilaire 400 (ducted) | Model 45 Water Panel, two supplied | Twice per heating season | 2 |
| Canopy (portable) | Antimicrobial filter | Every 45 days | 4.0 |
| AIRCARE MA0800 (portable) | MAF2 SuperWick | Not published | unknown |
| Levoit Superior 6000S (portable) | Four wick filters | Not published | unknown |
One or two panels against four filters, for the only two units in that table whose makers publish an interval at all - and the portable one uses four of them, not one. Add that the Superior 6000S takes four wicks per change and the consumable count diverges further still.
Why the ducted panel lasts so much longer
It is not the material. It is drainage.
A portable wick sits in a tray of standing water. Water is drawn up it, evaporates, and every dissolved mineral that came with it stays behind in the medium. Nothing removes it. The wick fills with mineral until it can no longer take up water, and then you buy another.
A ducted water panel does not sit in standing water. Water is fed across it continuously and the excess goes down a drain, carrying dissolved mineral out of the building. Aprilaire describes exactly this: a built-in drain flushes mineral build-up so water does not accumulate inside the unit. The panel is an evaporation surface, not a mineral trap.
Which panel fits which model
Water panels are not interchangeable and the model number is the thing to buy on. From Aprilaire's own product pages:
| Humidifier | Capacity | Water Panel | Notes |
|---|---|---|---|
| Model 500 | 12 gal/day | Model 10 | Small bypass unit |
| Model 400 | 17 gal/day | Model 45, two included | Water-saving design, so it captures excess rather than draining it freely |
| Model 700 | 18 gal/day | Model 35 | Fan-powered |
Note the Model 400 row. Aprilaire states that it uses 100% of the water that goes into the system by capturing excess water in a reservoir rather than sending it to drain. That saves water and it means the unit retains more mineral internally, which is the trade the water-saving design makes. There is no free lunch in this mechanism - only a choice about where the mineral ends up.
What it costs to own
We do not print a panel price - our live price layer tracks the humidifiers we feature rather than their consumables, and we will not publish a remembered figure. The multiplier is the part worth having, and here it is unusually favorable.
When to change it
- At the start of every heating season, as a default. It is the one maintenance task on a ducted unit and it is easy to forget precisely because it happens so rarely.
- Mid-season too, on hard water. Aprilaire's guidance is once *or twice* per heating season, and hard water is what pushes it to twice.
- When it is crusted white and rigid. A spent panel is visibly caked and stiff rather than pliable.
- If humidity has fallen with the humidistat unchanged and the furnace running normally. A clogged panel evaporates less, and the symptom looks like a controls problem.
- If it smells musty when the furnace fan runs. That is not a scale problem and a new panel alone may not fix it - see mold in a furnace humidifier.
The console middle ground
If you cannot install a ducted unit - no forced-air ductwork, no water line, or you rent - a console is the fallback, and its consumable behaves like a portable's rather than a panel's. The AIRCARE MA0800 takes a MAF2 SuperWick and the Levoit Superior 6000S takes four wicks, and neither maker publishes an interval.
That is worth factoring in before treating a console as the cheap alternative. It costs less to buy and its consumable schedule is both more frequent and less knowable. The capacity side of the same decision is on whole house vs room, and the sizing chart is on whole house humidifier sizing.
The picks, in full
Top pick · An actual whole house, sized against a standard
Aprilaire Model 700
Eighteen gallons a day against a stated 5,300 sq ft, cited to AHRI Guideline F. It is ducted, it needs installing, and it is the only sizing claim here with a standard behind it.
This is the reference point for the whole site. Aprilaire is the only maker in our set that publishes a capacity in gallons per day and a coverage in square feet together, and cites the residential sizing standard as the basis for pairing them. Three of its models do it consistently: 12 gal/day to 3,600 sq ft, 17 to 5,000, and 18 to 5,300. Those three pairs are where our 296 square feet per gallon per day comes from.
Everything else follows from the fact that it drains. There is no reservoir, so there is no standing water, so the pink film and the mold that dominate portable-humidifier ownership simply do not arise. The Water Panel goes once or twice a heating season instead of a wick every 30 to 60 days, which changes the recurring cost by an order of magnitude.
The honest counterweight is that this is not a purchase, it is a project. It mounts in ductwork, it needs a water line and a drain, it needs a humidistat and an outdoor sensor, and unless you are comfortable cutting into a plenum it needs a contractor. Our whole-house cost page works through the break-even against running several portables.
What works
- The only sizing claim in this set with a published standard behind it
- No reservoir, so no standing water and none of the maintenance that follows from it
- Water Panel changed once or twice a season instead of a wick every month or two
What does not
- Requires ducted forced-air heating, a water supply, a drain and, realistically, an installer
- Installed cost is a different order of magnitude from any portable here
- Wastes water: the drain design that keeps it clean also sends water to waste
Skip this ifyou rent, or you heat with anything other than a ducted forced-air system. Neither is a fixable objection.
The arithmetic
- Published output (continuous)
- 18.0 gal/day
- Covers, at 296 sq ft per gal/day
- 5,328 sq ft
- Maker’s coverage claim
- 5,300 sq ft
- Output that claim would need
- 17.9 gal/day
Output as the manufacturer publishes it. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- not publishedThere is no tank. It is plumbed to the water supply and drains to waste.
- Output/day
- 18 gal/daySource
- Coverage
- Up to 5,300 sq ftAprilaire states this for tightly constructed homes and cites AHRI Guideline FSource
- Power
- 24 VAC via the supplied transformerSource
- Filter
- Model 35 Water PanelAprilaire's maintenance page puts this on an annual schedule, plus an annual distribution-tray inspection. Its product page says once or twice per heating season; the two documents differ and we take the more specific one. Either way it is by far the longest interval of any unit here.Source
- Cleaning
- Built-in drain flushes mineral build-upWater does not stand inside the unit, which removes the standing-water problem entirelySource
#ad · how this is funded · price as of October 12, 2026
Pick 2 · Mist-free humidification with a drying cycle
Levoit Superior 6000S
Six gallons, evaporative, and a Dry Mode that dries the wicks between runs. The 3,000 sq ft claim needs five times the output its own run time implies.
Six gallons over 72 hours is two gallons a day, which covers about 590 square feet. The box says 3,000. To actually hold humidity across 3,000 square feet this unit would need to move a little over ten gallons a day, and at that rate its six-gallon reservoir would run dry in about fourteen hours. Both numbers describe the machine; only one describes it at a time, and the maker publishes no figure that reconciles them.
Dry Mode is the genuinely good idea here and it deserves credit. A wet wick sitting in a warm room is the substrate for everything the EPA warns about, and a fan cycle that dries the wicks between runs attacks that problem directly rather than adding an antimicrobial coating and hoping. It also extends wick life, which is the recurring cost.
Thirty watts to move two gallons a day is efficient, and mist-free operation means the minerals stay in the wicks rather than settling on your furniture. If you can live with a coverage claim you should mentally divide by five, this is a well-made machine.
What works
- Dry Mode addresses the real failure mode of evaporative units instead of masking it
- Mist-free, so no white dust whatever your water is like
- 30 W for six gallons of capacity, with noise published at both ends of the range
What does not
- The 3,000 sq ft claim is about five times what the published tank and run time imply
- Four wicks to replace, on an interval Levoit does not publish
- 45 dB at the top of the fan range is audible in a quiet bedroom
Skip this ifyou bought it for the 3,000 sq ft number. Size it at around 600 square feet on the setting whose run time Levoit actually publishes.
The arithmetic
- Implied output (low fan speed)
- 2.0 gal/day
- Covers, at 296 sq ft per gal/day
- 592 sq ft
- Maker’s coverage claim
- 3,000 sq ft
- Output that claim would need
- 10.1 gal/day
Output derived as tank capacity divided by published run time, times 24. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 6 gal / 22.7 LSource
- Output/day
- not published
- Coverage
- 3,000 sq ft / 279 m23,000 sq ft needs about 10.1 gal/day at our derived rate. Its published tank and run time imply 2.0.Source
- Run time
- Up to 72 hOn the low fan speedSource
- Power
- 30 WSource
- Noise
- 28-45 dBSource
- Filter
- Four wick filters, pre-installedReplacements are sold by Levoit as a four-pack. No replacement interval is published.Source
- Cleaning
- Dry ModeLevoit's own wording: low and high fan speeds dry out the elevated wick filters, extending filter lifeSource
#ad · how this is funded · price as of October 12, 2026
Pick 3 · A plug-in console with its own humidistat
AIRCARE MA0800 Mini-Console
A 2.5-gallon evaporative console with three fan speeds, an adjustable humidistat and a MAF2 SuperWick. Its 2,600 sq ft claim is far beyond what its own tank and run time imply, so size it as a large room rather than a floor.
Two published figures that describe opposite ends of the machine, and none of the numbers that would join them up. A 2.5-gallon tank lasting 36 hours is about 1.67 gallons a day, or roughly 493 square feet at our derived rate. Covering the claimed 2,600 square feet would take about 8.8 gallons a day, at which rate the same tank empties in under seven hours.
Both can be true at once: 36 hours is AIRCARE's maximum run time, which will be the lowest of the three fan speeds, and 2,600 square feet will be the highest. It can certainly move more than 1.67 gallons a day on a higher speed. AIRCARE does not say how much more, so its own published data supports sizing it as a large room, not a whole floor.
What it has that most units in our set do not is an adjustable humidistat with digital controls, stated on AIRCARE's own page. On an evaporative machine, which already slows down as the air approaches saturation, that is a second brake against overshooting - and the MAF2 SuperWick keeps your tap water's minerals out of the air.
What works
- Adjustable humidistat and digital controls, per AIRCARE's own specification
- Evaporative SuperWick captures minerals, so no white dust
- Three fan speeds to trade output against noise
What does not
- No published output figure anywhere on the manufacturer page
- The 2,600 sq ft claim and the 36-hour run time cannot both describe the same setting
- No published noise figure, wattage or wick replacement interval
Skip this ifyou want to humidify a whole floor on the strength of the box. Its own tank and run time support a large room, not 2,600 square feet.
The arithmetic
- Implied output (maximum published run time)
- 1.7 gal/day
- Covers, at 296 sq ft per gal/day
- 493 sq ft
- Maker’s coverage claim
- 2,600 sq ft
- Output that claim would need
- 8.8 gal/day
Output derived as tank capacity divided by published run time, times 24. Coverage rate derived from Aprilaire’s own published capacity-and-coverage pairs.
Published specification
- Tank
- 2.5 galSource
- Output/day
- not publishedAIRCARE's page gives a tank capacity and a maximum run time, but no daily output.
- Coverage
- Up to 2,600 sq ft2,600 sq ft needs about 8.8 gal/day at our derived rate. AIRCARE publishes no output figure, so the claim cannot be checked against its own data.Source
- Run time
- Up to 36 hAIRCARE's maximum run time, which will describe the lowest of its three fan speedsSource
- Power
- not published
- Filter
- MAF2 SuperWickAIRCARE publishes no replacement intervalSource
- Cleaning
- Evaporative wick holds minerals back from the roomAdjustable humidistat and digital controls, per AIRCARESource
#ad · how this is funded · price as of October 12, 2026
Questions people actually ask
How often do you replace a furnace humidifier pad?
Aprilaire's maintenance page states annually for Models 300, 500, 600, 700 and 720, and twice per heating season for the water-saving Model 400, plus an annual inspection of the distribution tray. Note that its individual product pages say once or twice per heating season - the two documents differ and the maintenance page is the more specific one. Either way it is an order of magnitude less often than a portable humidifier wick, because a ducted unit drains rather than holding standing water.
Which water panel fits my Aprilaire humidifier?
From Aprilaire's own product pages: the Model 500 uses a Model 10 panel, the Model 400 uses Model 45 panels with two included, and the Model 700 uses a Model 35. They are not interchangeable, so buy on the model number rather than on appearance.
Why do furnace humidifier pads last longer than portable wicks?
Drainage. A ducted humidifier feeds water across the panel and sends the excess down a drain, carrying dissolved mineral out of the building. A portable wick sits in standing water and keeps every mineral that passes through it until it can no longer take up water.
What happens if you do not change the humidifier pad?
It clogs with mineral and evaporates progressively less, so indoor humidity falls even though the humidistat and the furnace are working normally. The symptom looks like a controls fault, which is why a stale panel often gets diagnosed as something more expensive.
Is a water-saving furnace humidifier better?
It uses less water, which is a genuine benefit, and it retains more mineral internally as a result. Aprilaire states its Model 400 uses 100% of the water supplied by capturing excess in a reservoir rather than draining it. That is a trade about where the mineral goes, not a free improvement.
Sources
Every figure on this page came from one of the documents below, read on the date shown. We do not cite other review sites, forum posts or video reviews as sources of fact.
- Aprilaire Model 700 - manufacturer spec page (retrieved September 1, 2026)
- Aprilaire Model 500 - manufacturer spec page (retrieved September 1, 2026)
- Aprilaire Model 400 - manufacturer spec page (retrieved September 1, 2026)
- Canopy Humidifier - manufacturer spec page (retrieved September 1, 2026)
- AIRCARE MA0800 Mini-Console - manufacturer spec page (retrieved September 17, 2026)
- Levoit Superior 6000S - manufacturer spec page (retrieved September 1, 2026)
- US Environmental Protection Agency - Use and Care of Home Humidifiers (relative humidity ceiling, three-day cleaning interval, low-mineral water, microorganism warning)
Read next
Consumables
Wick vs Water Panel
Why a ducted Water Panel lasts a heating season and a portable wick lasts weeks, and what that mechanism means for cost of ownership.
Top pick: Aprilaire Model 700 · 18.0 gal/day
#ad · how this is funded · price as of October 12, 2026
Whole house
Whole house cost, against the portables it replaces
The ownership case for a ducted humidifier against multiple portables, with the consumable arithmetic and an honest statement of what we cannot cost.
Top pick: Aprilaire Model 700 · 18.0 gal/day
#ad · how this is funded · price as of October 12, 2026
Whole house sizing
Whole house humidifier sizing chart
Whole-house sizing by square footage, built from published manufacturer capacity-and-coverage pairs rather than copied from another chart.
Top pick: Aprilaire Model 700 · 18.0 gal/day
#ad · how this is funded · price as of October 12, 2026
Found a number that is wrong? Tell us and we will fix it and say so. How we pick shows every formula used on this page.