Which models does the GermGuardian Filter B (FLT4825) fit?

It fits AC4825E, AC4825W, AC4870, AC4820, AC4880, AC4300BPTCA, AC4300WPT, AC4900CA, AC4850PT, CDAP4500BCA, CDAP4500WCA, PureGuardian AP2200CA, Black+Decker BXAP150 — yes, a different brand. GermGuardian lists it on its own compatibility list, which is unusual enough to be worth knowing if you own one.. It does not fit GermGuardian sells filters under other letters for its other ranges. A filter that is not marked B is not this filter, however similar the purifier looks., The carbon pre-filter FLT22CB4 and the UV-C bulb LB4000 are not substitutes for Filter B and Filter B is not a substitute for them. All three are separate consumables on the same machine..

GermGuardian Filter B (FLT4825)

Q: What is the part number for the GermGuardian Filter B (FLT4825)?

FLT4825, FLT4825SM, FLT4825VO, FLT4850PT, FLT22CB4, LB4000.

By the NestyFinds editorial team · Researched from manufacturer documentation, manuals and the AHAM Verifide directory · Reviewed: September 2026

The part you need

FLT4825 · FLT4825SM · FLT4825VO · FLT4850PT · FLT22CB4 · LB4000

Filter B is GermGuardian's combined particle filter for its 22-inch tower purifiers, sold under several part numbers that differ only in the media formulation.

GermGuardian says: ⚠️ GERMGUARDIAN DOES NOT STATE AN INTERVAL FOR FILTER B ON THE PRODUCT PAGE ITSELF.

Check current price

Price, seller and package contents change. Check the variant on Amazon before you buy.

Does it fit your unit?

Fits these models

AC4825E
AC4825W
AC4870
AC4820
AC4880
AC4300BPTCA
AC4300WPT
AC4900CA
AC4850PT
CDAP4500BCA
CDAP4500WCA
PureGuardian AP2200CA
Black+Decker BXAP150 — yes, a different brand. GermGuardian lists it on its own compatibility list, which is unusual enough to be worth knowing if you own one.

Does NOT fit — commonly confused

GermGuardian sells filters under other letters for its other ranges. A filter that is not marked B is not this filter, however similar the purifier looks.
The carbon pre-filter FLT22CB4 and the UV-C bulb LB4000 are not substitutes for Filter B and Filter B is not a substitute for them. All three are separate consumables on the same machine.

Variants GermGuardian sells

FLT4825 (HEPA PURE) — the standard version.
FLT4825SM (SMOKE CLEAR) — media formulated for smoke.
FLT4825VO (TOXIN CLEAR) — media formulated for gases and VOCs.
FLT4850PT (PET PURE) — media formulated for pet odours.
All four are Filter B and fit the same units. GermGuardian publishes no comparative measurements between them, so there is no data on which to rank them — only the use each one names.

Units we have researched that take this filter: GermGuardian AC4825 .

What each part number is

FLT4825: "GermGuardian FLT4825 HEPA PURE Air Purifier Filter B". This is the standard version.
FLT4825SM: the same Filter B in the SMOKE CLEAR media.
FLT4825VO: the same Filter B in the TOXIN CLEAR media.
FLT4850PT: the same Filter B in the PET PURE media.
FLT22CB4: a SEPARATE activated carbon pre-filter, replaced every 2 to 3 months. Not part of Filter B.
LB4000: the replacement UV-C bulb. Also separate, and also a consumable.

What the manufacturer documents

What is in the set

Filter B is GermGuardian's combined particle filter for its 22-inch tower purifiers, sold under several part numbers that differ only in the media formulation.

The thing worth knowing before buying one is that Filter B is NOT the whole running cost of these units. The AC4825 and its relatives take three consumables on three different clocks: Filter B itself, a separate activated carbon pre-filter (FLT22CB4, every 2 to 3 months), and a UV-C bulb (LB4000). Most comparisons of this purifier against others count only the first of the three.

GermGuardian's own marketing copy for these filters makes claims about what the media captures that go well beyond dust and pollen. We do not reproduce them here: they describe the media on a test rig, not the air in a room, and they are the manufacturer's own statements rather than anything independently verified.

How often to change it

⚠️ GERMGUARDIAN DOES NOT STATE AN INTERVAL FOR FILTER B ON THE PRODUCT PAGE ITSELF. Checked 14-sep-2026: the page lists what the filter fits and states it is not washable, and gives no replacement period.

What the manufacturer does document on the same product page is the interval for the OTHER consumable: the activated carbon pre-filter FLT22CB4 is "replaceable every 2-3 months".

So on this unit the figure you can rely on is for the part that is not the main filter. Treat visible loading and airflow as the signal for Filter B rather than a date, and budget for the pre-filter four to six times a year regardless.

GermGuardian’s page for this filter

Genuine vs third-party filters

GermGuardian publishes no position on third-party filters that we could locate, so none is summarised.

What the manufacturer does state plainly is that Filter B is NOT washable. That matters more on this machine than on most, because the three-consumable design tempts people into cleaning the expensive part to save money — and washing a particle filter damages it invisibly, leaving a filter that fits and runs exactly as before.

That is GermGuardian’s stated position, reported as theirs. We have not tested third-party filters and make no claim about how well they work.

When something goes wrong

Symptom	Why it happens	What to do
The running cost turns out higher than expected.	Filter B is one of three consumables. The carbon pre-filter FLT22CB4 goes every 2 to 3 months and the UV-C bulb LB4000 is replaceable too.	Budget all three before comparing this purifier with one that has a single yearly filter. It is the honest comparison and it is rarely the one presented.
Unsure which Filter B version to order.	FLT4825, FLT4825SM, FLT4825VO and FLT4850PT all fit the same units and differ only in media formulation.	Any of them will fit. Choose on the use each one names, and be aware that GermGuardian publishes no comparative figures between them, so there is no measured basis for preferring one.
Owning a Black+Decker purifier and not knowing what filter it takes.	The Black+Decker BXAP150 appears on GermGuardian's own compatibility list for Filter B.	Check the model plate. If it reads BXAP150, Filter B is the part, even though the brand on the machine is different.
Washing or vacuuming Filter B to make it last.	It looks robust and the damage from washing does not show.	GermGuardian states it is not washable. On this design the part meant to be replaced often is the carbon pre-filter, which is cheaper by design.