GermGuardian AC4825 Air Purifier – Review


GermGuardian AC4825 is a simple air purifier that is extremely easy to use. There are no advanced features on the control panel, and because of that, this air purifier is ideal for people that love fresh air but don’t want to be bothered with too many options. AC4825 only has three speeds, but it is a 4 in 1 air purifier. 4 in 1 means that it uses four different cleaning air methods.

GermGuardian AC4825 Air Purifier Review - Featured Image

We must say that even though it doesn’t have advanced features, this air purifier is one of the most popular air purifiers on the market. Without a doubt, this air purifier is one of the best sellers from the Guardian Technologies company. 

GermGuardian AC4825 is built for a 167 sq. ft. room and uses UV-C light to kill germs and mold spores.

GermGuardian AC4825 Air Purifier Placed On Desk

UV-C light is proven to be extremely effective at killing germs, mold spores, and even some viruses. This advanced technology is part of the air purifier and can be turned on or off at any time.

UV-C light is not the only technology that cleans the air in the GermGuardian air purifier; this popular air purifier also uses a pre-filter, HEPA filter, and activated carbon filter.

GermGuardian AC4825 removes pollution from the air, but this simple air purifier also has the power to eliminate germs, mold spores, and some viruses.
View On Amazon

GermGuardian AC4825 Specifications

Below is a complete list of important specifications and features included on the GermGuardian AC4825 Air Purifier:

Manufacturer Guardian Technologies
Model AC4825
Dimensions 9 x 5.5 x 22 inches
Filters Pre/Charcoal Filter and True HEPA Filter
Filter Longevity up to 6 months
Coverage 167 sq. ft.
Power Consumption 55W
Warranty 3-year limited
User manual PDF


By the looks, we can say that AC4825 uses tower shape design. This tower-like design is proven to be useful because it can be placed in tight spots. Many other brands use tower shape for their devices, and we can even say that this tower-like design can be put in the special category when talking about air purifiers.

GermGuardian AC4825 Air Purifier Design

The black color is the brand of this model, and almost the whole device is in black. Only the top is in silver color with a blue line that emits light. On top is the control panel. However, there are not many options to use, the UV-C light button and fan speed knob. By turning the power knob, you also control speed and turn the air purifier on or off. UV-C light button is also a filter replacement button that is used to reset the filter replacement period. 

On the back is an air inlet and on the front is an air outlet, so keep that in mind when you want fresh air delivered directly into your face. On the back of the air purifier is also a hole that is used for transport. You can transport it with one hand. The overall design is nothing special.

Control Panel

As already mentioned, the device is turned on with a power knob. By moving the knob in the clockwise direction, you can also control fan speed. The device has three speeds; low, medium, and high

GermGuardian AC4825 - Controls

A button with UV letters is used to turn the UV-C bulb on. This button is also used to reset filters and UV-C light. We will talk more about the reset function later in the review.

In the end, when the air purifier is done with the job, you can turn it off by moving the power knob back into a default position.

Size and Dimensions

GermGuardian AC4825 is tall (9 x 5.5 x 22 inches) but small with only 8.55lb in weight. It also has a handle on the back for easier transport. You won’t have any problems moving it from one location to another.

The back handle that is used for easy transportation between rooms is slippery, so be careful when moving it.

Accessories and Parts

When you buy GermGuardian AC4825 in the package, you will get one air purifier, one true HEPA filter, one pre-filter combination with charcoal filter, a UV-C bulb, and a user manual.

GermGuardian AC4825 Video Review

Check out the video and see GermGuardian AC4825 in action. All our tests are documented in detail. Also, we recorded additional tests that are not mentioned in the review.


Certified Device

GermGuardian AC4825 is a certified device that guarantees quality. It has EPA, CARB, Energy Star, and AHAM certificates. In other words, you can’t go wrong with this device if you only look at the certificates.

No Ozone

GermGuardian AC4825 is free from ozone, and that is true. Proof of that is the CARB certificate. Some air purifiers produce ozone but not AC4825.

Silent at Work

Silence is essential for the bedroom because loud noise can bother your sleep. Put the air purifier on the first speed, and you can sleep like a baby.

Room Coverage

This device is built for up to 167 sq. ft. rooms. In the recommended room size, this device will provide the best performance. However, if you need a stronger device, you can take a look at the Levoit Core 300 model.

The UV-C bulb is turned off by default, if you are suspicious about UV-C light function, you never have to turn it on.


A three-year warranty is more than generous from Germ Guardian. However, you will need to register your device on the Germ Guardian website to use the full three-year warranty.

It Can be used in combination with a smart plug. But you will need to turn on the UV-C light manually, as the AC4825 does not remember if the UV-C light was on after the device was turned off.

CADR Ratings

CADR ratings are the way we can see the difference between the filtration power among air purifiers. Each rating is important, and you can pick an air purifier that best fits your needs.

For example, if you have smoke or odor trouble at home, then look at CADR for a smoke. Check out the table below with all the CADR ratings of GermGuardian AC4825.

Smoke 108
Dust 118
Pollen 125


The filter is the most important part of every air purifier. All airborne pollution, dust, pollen, pet dander, hair, and even mold spores are removed with a filter.

GermGuardian AC4825 - Filters
All in one filter is simple to replace and, at the same time, a perfect solution to remove airborne particles from the air.
View On Amazon

The filter is delicate and needs to stay dry for maximum performance. Because of that, never use an air purifier in areas with high moisture. The filter is not reusable, which means you should never wash it or clean it. These actions may damage the filter, and you can have even more pollution at home than before.

Essential oils on the filter are big no. Oils can destroy filters and even damage the air purifier. If used properly, the filter needs to be replaced every six months.

True HEPA Filter

True HEPA filter destroys up to 99.97% of harmful germs, dust, pollen, pet dander, mold spores, and other allergens as small as 0.3 microns from the air.

GermGuardian AC4825 - True HEPA Filter

We keep the True HEPA filter at top performance by using pre-filter and regular filter replacements.

Pre-filter + Charcoal

A combination of pre-filter and charcoal is not the happiest combination because this means that there is not much carbon to remove all the bad smells in the room. However, charcoal pre-filter will still be useful at removing odors at a decent time. It would be much better if instead of a charcoal filter, a carbon pellet is used. 

GermGuardian AC4825 - Pre-filter and Charcoal Filter Combination

Nevertheless, pre-filter will remove larger particles, dust, and some allergens. The charcoal filter prevents excessive accumulation of odor but also reduces the growth of bacteria, germs, and mold.

How to replace GermGuardian AC4825 filter?

Step 1

Turn off the air purifier, make sure the power cable is also unplug. After that, open the rear cover by pressing the lock and release button.

GermGuardian AC4825 Replacing-Filter - Step 1

Step 2

Remove the old filter from the air purifier.

GermGuardian AC4825 Replacing-Filter - Step 2

Step 3

Put the new filter into the unit. Check the arrow on the filter to place it correctly inside.

GermGuardian AC4825 Replacing-Filter - Step 3

Step 4

Put the cover back and seal it.

GermGuardian AC4825 Replacing-Filter - Step 4

Step 5

Lastly, press and hold the UV Control Button for 5 seconds to reset the Filter Change Indicator.

GermGuardian AC4825 Replacing-Filter - Step 5
The device will not start if the back cover is not closed correctly. This security feature is great and will prevent UV-C light exposure.

UV-C Bulb

UV-C light is one of the best ways to kill dangerous microorganisms. Many manufacturers started to use UV-C light in their air purifiers to provide even greater performance.

GermGuardian AC4825 - UV-C Light Bulb

UV-C light is safe to use in certified air purifiers.

View On Amazon

The GermGuardian AC4825 UV-C bulb position is not the best. It would be much better if it is placed somewhere in the middle of the device and not on the top. UV-C light technology works with Titanium Dioxide. Titanium Dioxide is activated by UV-C light and, in combination, kills germs but also removes odor molecules, smoke, cooking odor, and even pet odors.

When UV-C light is on, you will see the blue light on the front panel. UV-C light is safely contained inside the air purifier, and using it is perfectly safe.

UV-C bulbs need to be replaced every 10 to 12 months.

How to replace UV-C bulbs?

Step 1

Again remove the back cover, but also make sure the device is unplugged. Immediately after, remove the filter from the air purifier.

GermGuardian AC4825 Replacing UV-C Bulb - Step 1

Step 2

Remove UV-C metal shield with Phillips screwdriver.

GermGuardian AC4825 Replacing UV-C Bulb - Step 2

Step 3

Use the clean cloth on the UV-C bulb and remove it out from the unit.

GermGuardian AC4825 Replacing UV-C Bulb - Step 3

Step 4

The UV-C Bulb is reinstalled by pushing it horizontally back into the holes at the unit’s top.

GermGuardian AC4825 Replacing UV-C Bulb - Step 4

Step 5

Press and hold the UV Control Button for 5 seconds to reset the UV Bulb Change Indicator.

GermGuardian AC4825 Replacing UV-C Bulb - Step 5


We have tested this device in various situations and different fan speeds. What I like about AC4825 is the difference in noise at a different speed. Some models have third speed extremely loud, but not GermGuardian. Still, in general, noise could be a little bit lower. 

On the first speed device makes 46.7 dBA, on second speed, 50.5 dBA, and on third speed, this air purifier makes only 54.2 dBA. It is clear that this device needs sleep mode, which could reduce noise at a lower speed even more. As always, we used a measuring tool that uses the dBa scale, and our results may be different from the official ones. Check out the table below for more details about the noise.

Speed Value (dBA)
Speed 1 46.7 dBA
Speed 2 50.5 dBA
Speed 3 54.2 dBA

Performance Tests

We tested this air purifier in different rooms. Only the most significant tests will be included in this review. Overall, this device did a good job. We tested it with UV-C light and without it.

GermGuardian AC4825 - Performance Test

Our pollution measuring tool did not find a significant difference in these tests. We must say that our tests are done in real-life situations, and we did not do any tests in the laboratory.

320 sq. ft. Room

In this large room that is almost two times larger than the recommended one, our test device did a good job with excellent results. In only one hour of work, AQI dropped from 80 to 8 and improved air quality by 90%.

# Starting Baseline After 60min
PM 2.5 59.4 6.1
PM 10 83.2 8.6
Particles 86210 8972
AQI 80 8

320 sq. ft. Room With UV-C Turned On

In the same room size, but now with UV-C light on, results were not significantly different. AQI drops from 85 to 8, which is 91%. We can say that UV-C light gives an additional 1% boost, which is not that much after all.

# Starting Baseline After 60min
PM 2.5 63.4 6.1
PM 10 88.8 8.5
Particles 92029 8889
AQI 85 8

194 sq. ft. Room

This room is almost the perfect size but still a little bit larger than the recommended one. Again there is not much difference between the tests. In 60 minutes, AC4825 managed to drop AQI from 85 to 7, which is 92%. Again an excellent job.

# Starting Baseline After 60min
PM 2.5 63.6 5.4
PM 10 89.1 7.5
Particles 92363 7837
AQI 85 7

However, if you need a much stronger device that is meant for larger rooms, check out Winix C535 or Oransi OV200. These two devices have almost two times more power than AC4825.

Operating Costs

AC4825 is powered by a 50W engine that pulls 55W when at full speed and with the UV-C light turned on. These numbers are not high, and you won’t see any significant charges on your electricity bill. In whole month work, 24h every day, this device will cost you only 3.8$ if we consider that the US’s electricity price is 0.12$ per kWh.

GermGuardian AC4825 - Motor Performance

When on standby, the device will not use any power. With UV-C light energy consumption is higher but not significant. A much higher operating cost is filter replacement, which needs to be replaced every six months. GermGuardian is an energy star certified device but if 55W is too much for you, then take a look at Blueair 411, which uses only 10W of power.

Speed Power Usage (W)
Speed 1 30.8W – 35.1W*
Speed 2 34.8W – 38.6W*
Speed 3 39.0W – 43.1W*
Stand-by 0W

* This was power usage with UV-C bulb turned on.

Pros and Cons

To revise, here are advantages and disadvantages of AC4825:


  • AHAM Verified
  • Energy Star Certified
  • Popular Device
  • True HEPA Filter
  • UV-C Light Kill Germs
  • 3 Year Warranty
  • Filter and UV-C Replacement Indicators
  • Good Value For Money
  • Great Performance


  • Bad UV-C Position
  • No Sleep Mode
  • Charcoal Filter Could Be Better
  • Too Expensive Original Filters

Final Thoughts

GermGuardian AC4825 is an old-style air purifier with great popularity on the market and excellent performance. It is unbelievable that this device comes with a True HEPA filter for such a low price.

GermGuardian AC4825 has proven itself in our test, and there is a real reason why this device is so popular on the market. And in the end, all we can say is buy it; you won’t regret it.



Review Breakdown





Operating cost


Value for money


Ease of use


Update Log

December 3, 2020 – I embedded a video review of the GermGuardian AC4825 from Air Purifier First YouTube channel. Also, I added a rating of the AC4825 air purifier to the review.

October 8, 2020 – We have completely updated the GermGuardian AC4825 review with all new important things: noise tests, filter tests, performance tests, operating costs, filter replacement guide etc.

Subscribe To Our FREE Air Purifier First Newsletter

By entering your email address you agree to get a weekly email newsletter from Air Purifier First. We'll respect your privacy and unsubscribe at any time.

Leave a Reply