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GermGuardian AC4825 Owner’s Honest Review – A Good Buy?

After having to deal with dust and other air quality issues, I picked up a GermGuardian AC4825 of my own. It wasn’t hard to find – after all, it’s one of the most popular purifiers sold today. Just like I first did, you may be wondering exactly how good it is, you want to know the pros & cons, and also whether or not it’s worth your money.

In my GermGuardian AC4825 review I’ll help you decide if it’s a good buy or not. I’ll also share with you the good and bad to be aware of.

I’d love to help you make the best buying decision for your money and experience better air at home just like I have. Believe me when I say a good air purifier is definitely a great purchase – but you’ve got to shop wisely!

Read on to learn more. You can also click here to jump to the review score and pros & cons.


My AC4825 video review

The GermGuardian AC4825 – Unpacking & first impressions


I’m no stranger to air purifiers and home air quality products, so I didn’t think I would get excited about another air purifier. It turned out I was wrong.

For some reason, it was still fun to pick up my AC4825 from the UPS Store for the first time and unbox it. What is it really like, I wondered? How well does it work?

GermGuardian AC4825 review package image

My AC4825 arrived quickly and after removing it from the FedEx box, inside was a great-looking package. The box is well-designed and highlights the many great features and health benefits of the product. Overall, it’s a great looking package. Not at all cheap-looking or “skimpy” like some of the competitors! Also, it clearly states the replacement filter required. That’s a nice touch. We’re off to a great start!

Build quality

GermGuardian AC4825 review front view image 1
After opening and unpacking it (which consisted of removing the corrugated cardboard inserts – styrofoam isn’t used with this one) I finally to check it out and turn it on!

The AC4825 is built with a solid, good-feeling ABS plastic body and has a nice low-gloss black finish. The top features a matte silver finish with a satin black top section surrounding the controls.

I didn’t get any kind of impressions of it having any poor-quality construction or any similar flaws. It looks good, and honestly I’m happy with it. Personally, I’ve never been a big fan of extremely glossy finishes on anything, so it doesn’t stand out in any rooms I’ve used it in. While being modern and contemporary in style, it still remains somewhat subdued and respectable in appearance.

The purifier is put together well. Parts are aligned well, are tightly assembled, and there aren’t noticeable gaps or quality control issues to speak of. Overall, it looks well made. If there’s one thing I’ve learned over the years, it’s that gaps and misaligned parts are a sign of build issues.

I’m happy to report that isn’t the case here.

The controls – how good are they?

Operating the AC4825 is extremely easy. In the picture above, you can see 1) the 3-speed fan control, and 2) the ultraviolet-light (UV-C) germ killing feature button switch.

The fan control feels great, and the switching is somewhere between a “soft” feel and a firm feel. It’s not too light, and yet not too hard to turn. I’m pretty happy with it, because it doesn’t feel like you’re going to miss position #2 and skip over to #3, for example. The fan switch is actually fairly quiet in operation and smooth to use.

The ultraviolet light (UV-C) germ killing feature

The AC4825, like several other GermGuardian air purifier models, features a bulb and titanium-oxide germ killing feature which irradiates germs passing through it and renders them inactive by affecting their molecular and protein structures. However, you’ll have to manually turn on this option.

In order to do so, the purifier must be at least in position #1 (low speed) before touching the pushbutton. The function is indicated as being turned on by the glowing blue trim around the body, seen here.

GermGuardian AC4825 side view UV-C feature glowing

When activated, you’ll see the small, thin trim on the base of the silver decorative top glow blue from the UV bulb inside. Don’t worry – you’re not in any danger from exposure to ultraviolet light. It’s safely contained inside.

I like how this feature was turned into a decorative accent when active.

One complaint I have, however, is that once it’s in use, switching the purifier off then on again won’t re-activate the feature. You’ll have to do so manually, as there’s no memory feature to turn it on automatically.

This means that if you use an automatic outlet timer as I do to turn the purifier on and off every day you won’t be able to use this option as well.

While not a “deal breaker”, it’s something to be aware of.


GermGuardian AC4825 Specifications
  • Room size rating: 155 sq. ft (medium room)
  • UV-C germ killing light
  • Titanium Oxide odor molecule remover
  • 3-speed fan control
  • True HEPA filter w/ activated carbon filter
  • CADR Rated 101+ (Clean Air Delivery Rate)
  • Low-noise fan setting
  • Replaceable UV bulb
  • Dual-section blower fans
  • Simple rotary control
  • Pushbutton on/off UV switch
  • Filter replacement reminder
  • UV bulb replacement indicator
  • 3-year limited warranty
  • Replacement filter: FILTER B (FLT4825)
  • Carrying handle
  • Weight: 8.65 lbs
  • Cord length: 6 ft.
  • Control location: top
  • Size: 6.75 x 10.25 x 21.5″

Size and thoughts on using a “tower” purifier

AC4825 purifier measuring height

At nearly 22″ in height, it’s definitely not a small device. “Tower” air purifiers are simply those that are taller and don’t have a low-profile design and stand tall on the floor. They normally are taller due to having additional fans in order to provide more air flow.

It’s important to make sure you have sufficient room before buying. A great location is near the door and not placing it backed into a corner in the room. Be sure to give it lots of room as it needs space both the front and the rear to move air.

Carrying the purifier

GermGuardian AC4825 being carried by handle

One thing I really like is being able to carry it easily from place to place at home using the built-in carrying handle area. At the rear of the top, there’s a recessed area where your fingers have plenty of room to pick it up securely.

It’s a nice touch I didn’t notice at first bout after moving it around to find the optimal place in my home, I found it handy.

Air cleaning ability & performance

As it’s rated for up to 155 square feet by the manufacturer, it’s well suited for medium sized rooms, although there’s absolutely no reason you can’t use it in small bedrooms. You can also use it in rooms somewhat above the specified 155 sq. feet – that’s an estimate.

I’ve let it run all day while at work so I could come home to fresh, clean air, and it works well. The thing to remember is that air purifiers work by cycling air in a room and it takes time to cycle & filter the entire room’s air.

GermGuardian AC4825 square feet coverage and room size

This model is recommended for room sizes that are approximately medium in size. That being said, there’s absolutely no reason why it can’t be used in a small room! In fact, you’ll find that it cleans the air even faster in that case.

It’s sized for rooms about 155 square feet in size which is roughly a 10 x 15.5 ft room. Bear in mind that this is an approximate size used – it doesn’t have to be used in a room exactly that size.

When used in larger rooms the amount of time required to fully cycle and clean the air increases accordingly.

Filter ability

AC4825 FLT4825 HEPA filter up close

The AC4825’s HEPA filter (seen here) section is made up of a folded, dense fiber material. It’s capable of excellent filtering ability and works well. The filter can capture almost 100% of all particulates in its airflow down to 0.3 microns in size!

The high efficiency particulate air (HEPA) filter is fantastic for removing the most common air quality issues (especially those that cause allergies!).

Here’s the basic list of air contaminants the AC4825 can remove:

  • Pet dander
  • Pet hair (thanks to the pre-filter)
  • Dust mite allergens
  • Pollen
  • Dust
  • Home construction particles
  • Smoke residue
  • Smoke odors
  • Chemical and organic odors
  • Chemical vapors

Essentially, this is a 3-in-1 air cleaning system as the filter assembly is made of 2 main parts: the pre-filter/activated carbon filter and an additional 2nd section, the HEPA filter for a total of 3 filters.

The pre-filter section is a less dense & thin section covering the active carbon filter. It’s job it so first capture larger items in the air like pet hair, dust, and so on. The active carbon filter traps odors and other chemical substances in the air.

Finally, the HEPA filter captures an amazing 99.97% of particles passing through it down to 0.3 microns in size. That’s less that 1/1,000,000 of a meter! That means it’s capable of capturing elements that are microscopic in size.

It’s a great filter and works well. I noticed fresher air soon after using it for the first time, and a I’m pleased with it.

The UV-C germ killing feature explained


By touching the UV button on top, you switch on the germ killing which is a great addition not found in many competing products. It’s perfectly silent and doesn’t cause any noise or produce any side effects.

The blue trim on the base of the silver top section glows blue to indicate when it is in use.

The technology is based on the ability of ultraviolet light (UV) to affect microbes in the air. As stated in the owner’s manual:

UV-C light technology works with filters to enhance the elimination of airborne germs. Titanium Dioxide is activated by the UV-C light to decompose remaining odor molecules
caused by smoking, cooking and pets.

- AC4825 owner's manual

Essentially, air passing through has the UV light irradiating into it and microbes in the air are destroyed. It can help prevent sickness and other respiratory problems caused by germs.

Does the AC4825 produce ozone?

Some people wonder if air purifiers can cause headaches. As I explain more in this post, an air purifier based on filtering the air doesn’t produce any emissions. Therefore the GermGuardian AC4825 cannot cause headaches.

The UV-C option is completely enclosed and you’re in no danger of skin UV exposure. The purifier itself is 100% safe and there’s nothing to be concerned about. It doesn’t produce any ozone.

Filter & UV bulb replacement indicators & cost

Replacement indicator lights

The purifier features a helpful way of indicating when it’s time to check and possibly replace the filters. After about 6 months of use, the green LED near the fan switch will blink red to indicate this (see the chart below).

If your filter has had very light use and isn’t heavily used, you can reset the indicator by holding the UV-C button for 5 seconds.

In the case of replacement for the UV-C feature’s bulb, the blue light will blink.

Blinking Light TypeMeaning
Blinking blue light(UV-C glow trim blinking) UV bulb needs replacement
Red blinking lightFilter needs check/replacement

Filter life and costs

GermGuardian FLT4825 replacement filter
The FLT4825 is the genuine replacement filter from GermGuardian. It includes both the HEPA filter and an active carbon filter section, too. While the genuine replacement filter is only around $30+, you can save money by buying 3rd party replacement filters.

Expect to replace a filter after about 6-8 months; however, this depends greatly on use. For example, if you’re a smoker or have indoor pets you can definitely expect to replace the filter when reminded. For lighter use the life will be extended even further.

Replacement filters cost around $30 (or a bit over that) for the genuine GermGuardian brand. However, 3rd party budget models are available which contain 1 less expensive filter or 2 filters in the box. If you’re concerned about maintenance costs that’s a great option.

How hard is it to replace the filter?

GermGuardian AC4825 filter removal image
Filter replacement is easy and only takes a few seconds. I was pleasantly surprised with how easy it is.

Basically, it’s just a few simple steps:

  1. Press down on the release tab on the rear cover
  2. Pull the cover down and out (there a 2 tabs on the bottom which sit in tab slots)
  3. Using your fingers, pull the filter out and down to remove it
  4. Replace filter using the opposite motion
  5. Insert the cover’s tabs in the base
  6. Swing the cover up and snap the release tab back in place

…and you’re done! I’ve demonstrated this in my video review as well, so be sure to watch that if you’re interested.

UV-C bulb replacement & pricing

LB4000 UV replacement bulb

The GermGuardian replacement bulb #LB4000. Expect to pay around $25 or so for one when replacing it.

Replacement bulbs cost about $25. In order to replace the bulb, you’ll need a Phillips head screwdriver to remove the rear metal bulb cover. It’s accessible once you’ve removed the filter after opening the cover.

Once the metal cover is removed you simply slide out the old bulb and replace it with a new one. Overall, it’s easy to do.

The bulb is rated at 10-12 months life expectancy, although a few owners have reported that their bulbs died after only a few months.

The owner’s manual

Germguardian AC4825 manual image closedGermguardian AC4825 manual image open

I was pleasantly surprised to find that the purifier included a solid, well-made owner’s manual with clear instructions and helpful information. Basic information like replacing the filter,UV bulb replacement, and user operation is clearly explained. Also, it the printing is great and I have no complaints! It’s provided with French and Spanish sections as well.

After unboxing my new purifier I reviewed the instructions and found the owner’s manual to be very clear and helpful. It is provided in English, French, and Spanish. At only 20 pages long, it’s fairly concise, but it’s good. The manual tells you the basics you need:

  • How to operate your purifiers
  • The indicator lights (power, air filter replacement reminder, and UV light bulb replacement)
  • Replacement filter model specifications
  • Power consumption
  • Specifications: size, weight, and square feet coverage

The English section is very clear and helpful. It contain 12 pages of information you’ll want to review before operating it, but honestly? This model is so easy and hassle-free to use you won’t need instructions, ha ha.

Don’t worry, I won’t leave any of the specifications off – I’ll provide them below.

(If you like, you can download the GermGuardian AC4825 manual here for your convenience)

Noise levels during use

The company claims that the unit has low noise during use, and in my experience it’s true.

Setting #3 (high) is a moderate level of noise but can be masked by the sound of your TV or radio, for example, but it’s still noticeable. Ordinarily you won’t likely need to use the high setting except for immediate and the maximum possible cleaning of air for odors, smoke, etc.

Medium (setting #2) is actually not very loud. When in use while I’m listening to YouTube videos or playing music, it’s very easy to forget it’s even on. Low speed is indeed fairly quiet, and suitable for sleeping if you’re not a light sleeper like me (I have problems with any sounds during sleep as I’m a light sleeper).

When on low, most people will be fine to sleep as it’s very quiet. While not quite as quiet during low-speed as products like the Levoit LV-H132, for example, I’m happy with it. The main reason that the AC4825 is a few decibels louder is because it contains not one but 2 fan sections and naturally produces a bit more sound.

That’s a trade-off when using a more powerful purifier like this.

Volume measurements

I measured volume levels using a nice digital decibel sound level meter at 1 meter (3.28 ft) from the purifier.

Measurement/SpeedVolume (dB)
Off (room noise)39.3

A note about the sound while running

I do have one minor gripe: while in operation, and although it’s fairly quiet, there’s a characteristic sound these devices produce.

Because of the dual-fan section design as well as both the motor and its electrical drive, the combination of these factors causes it to produces a “whirring” noise while in use. The noise isn’t annoying or bothersome in my opinion, but it’s something to be aware of beforehand.

Night brightness

Image of GermGuardian AC4825 in dark

The top-facing power-on LED is a green soft-glow type of indicator. It’s not too bright in nature, but still slightly noticeable in the dark. The blue glow being produced when the UV-C feature is in used isn’t very bright, but the human eye is more sensitive to blue light.

For that reason, my opinion is that for many people it will be fine, but if you’re especially sensitive to light when concentrating on a task on sleeping it could be an issue. In that case I recommend leaving the UV turned off during those times or alternately relocate it or place it out of the way.

Not to worry though: the light brightness isn’t enough to “light up a room” or something unacceptable like that. They have more like a soft glow.

The AC4825 vs AC4900CA – A cool looking twin worth checking out

AC4900CA side view in home

The AC4825’s counterpart is the AC4900CA. It’s identical in features and performance. Interestingly enough, sometimes it can be found for a few dollars less!

You might not know this, but the AC4825 actually has a sibling called the AC4900CA, which is identical in performance, features, and specifications. It’s simply styled differently and doesn’t have the blue glowing ring for the UV-C like its counterpart.

I’ve thoroughly compared the two here: GermGuardian AC4825 vs AC4900CA.

I’ve seen it sold for a few dollars less (for example here at Amazon) and I personally think the styling is nice. It’s definitely worth considering, as while not as popular as its counterpart it has the same great quality and is otherwise identical.

AC4825 vs AC5000 comparison

GermGuardian AC4825 vs ac5000 comparison photo

The “big brother” to the AC4825, the AC5000E is nearly identical except for room size coverage and the UV-C bulb. It’s a great addition to your home as well. Be sure to check out my detailed comparison if you’re interested in the AC4825 but have a large room!

In case you’re not familiar with it, the AC5000 is almost identical except for its size (near 28″ tall) and room size coverage. It too is an excellent large-room air purifier and is recommended for rooms up to 193 square feet in size.

Just like the AC4825, it features a UV-C germ killing feature although the bulb design is different. I’ve enjoyed owning one so much that I wrote a detailed comparison of the AC4825 vs AC5000 here.

GermGuardian AC4825 vs the Honeywell HPA100

Honeywell HPA100 air purifier image

The closest rival to the AC4825 in my opinion is the Honeywell HPA100. It offers some features the GermGuardian doesn’t, although it’s lacking in a few areas. It’s also available in a white version. Room size coverage is also 155 sq. ft.

In my opinion the AC4825 is a solid, well-built, and easy to use purifier. However, there’s definitely no shortage of competition. Although it can’t come close to the popularity of the AC4825, the Honeywell HPA100 is a solid contender with identical room size coverage.

As I’ve reviewed several other Honeywell models like the HPA160 you see here, I cant verify their quality and they’re pleasant to use.

Some of the features the HPA100 offers that the AC4825 doesn’t are:

  • Electronic touch controls
  • A Turbo high-speed setting
  • Auto-off timer

However, there’s no germ killing feature offered. That’s absent in the Honeywell HPA series of purifiers, and it’s a shame. You’ll also pay a few dollars less for the GermGuardian model as well.

Additionally, the pre-filter in the HPA series is a little bit more thin than the GermGuardian family uses. The touch controls of the HPA100 are nice to have but to be honest, I’ve haven’t missed them at all.

I still use my AC4825 regularly and find it so simple and easy to use…it’s still one of my favorites! However, if having an auto-off timer is an important feature for you, it’s worth your while to check out the good reviews and current price for the HPA100 at Amazon today.

How to add an automatic timer

The AC4825 doesn’t include an auto-timer feature, sadly. My work-around is to use to automatically turn the purifier on and off during the day and to clean the air unattended.

Unfortunately, unlike the Honewell HPA100 purifier I mentioned above, the Ac4825 doesn’t have an auto-off timer built in so you can let it run and turn itself off. However, there is a work-around.

I really wanted this feature, and the lack of it is one complaint I have. Using an electrical outlet timer I bought for below $10 online, I can power my air purifier and have it run all day while I’m not home and arrive home to lovely, fresh air!

One complaint I have is that the UV-C feature doesn’t turn back on if it was in use before you switched off the purifiers using the fan control. There’s no memory feature, so you’ll have to turn it back on manually every time you’d like to use it.

Review summary

I’ve enjoyed every minute I’ve owned it. Overall it’s a great purifier you’ll be happy to own just like I have!

It’s at many stores like Walmart, Target, Lowes, and Best Buy, but you’re far more likely to pay more at those in my experience.

I highly recommend you check it out at Amazon where it’s cheaper. You be blown away by the amazing number of great reviews there and how many happy owners swear by it.

Do you like the AC4825 but not how it looks?  Be sure to check out the AC4900CA, its twin with a different style but identical performance.

8.8 Total Score
A well-performing air purifier that you'll be glad to own. No frills, but solid performance, low noise, and easy use make it one of the most popular models today.

The GermGuardian AC4825 is a no-frills tower air purifier with simple operation and good air cleaning ability. It lacks in features compared some other products, but it's a better value for its price range. Room coverage (med. rooms) is better than many similarly priced competitors. The quality and fit & finsish are nice. Maintenance is easy to perform. Operation on low speed is quiet enough for most. One of the best-selling air purifiers available today, it's a great choice and works well for dealing with allergies, smoke, pet dander, and many more air quality issues. You won't go wrong with this one!

Ease of use
Air cleaning ability
Noise levels
  • Great air coverage for its price range
  • Very easy to operate
  • UV-C feature kills germs - not found in many comptetitors
  • Carry handle built-in
  • Dual-fan design
  • Filter replacement reminder
  • UV bulb replacement reminder
  • 3-year warranty
  • 3-in-1 air cleaning system
  • Maintenance is easy to perform
  • Low operational noise
  • Reliable
  • Highly effective & true HEPA level filtering
  • Well-built
  • Available in functionally identical AC4900CA model
  • Prefilter/carbon filter section can be replaced separately from HEPA section
  • Nice design & weight won't tip over easily
  • UV-C feature must be turned on manually after power off then on
  • No auto mode or auto-off timer feature
  • Blue glowing trim could be noticeable to some with high sensitivity
  • Tall height may not be suitable for all users
  • Rotary manual control fan speed switch
  • No other color options available (aside from AC4900CA)
  • You'll need to buy 3rd party filters to save money as originals are more expensive
  1. Would I get good results using the AC4825 in a 600sq ft living room and change locations frequently

    • Hi there Jo! You could do that…but it greatly depends on what type of air quality problem you’re dealing with.

      But honestly, that’s right at 4 times the size of rooms it’s recommended for. That means it would take 4 times as long to cycle and clean the air in that room. I can’t really recommend it in that case.

      I would honestly at least recommend getting two of the AC5000 (193 sq. ft) models. 600 square feet is quite a bit.

      You could also check out the Honeywell HPA300 (465 sq. ft) which is a nice model here: and a good value for the room size coverage. It has some extra features, too.

      I’d like you to spend your money on what’s most beneficial to you, so have a look at that one. It’s nice and very powerful. I enjoyed using it.


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