How Large An Air Purifier Do I Need?

Can an air purifier be too big for a room?

Will it do a great job of cleaning the air than a purifier with the right space rating?

That’s what we are going to find out in this short post.

In another article, we saw the meaning of air changes per hour (ACH). We also said this is downright one of the top considerations when you are buying an air purifier. Space rating and ACH!

So, can an air purifier be too large for a room? No and yes. An air purifier with a bigger space rating than the size of your room will make more noise. On the other hand, it will do a faster job, cleaning the air with a few air changes per hour only.

If you are going out to buy an air purifier, do not buy an oversized one. Okay, you can get one that is just slightly larger for your space.

For instance, if you are purifying the air in a 250 sq. ft room, it is alright to get one that has a space rating of 300 sq. ft.

What to do if your air purifier is too big

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It is quite possible to have a bigger air purifier than you need. This does not have to be a whole house air purifier. Some portable units are really large.

If you have a small apartment and you have a large unit such as the Honeywell HPA300 Air Purifier, don’t worry. You can still use it in a small room.

Set a lower working speed – lower air change per hour rate

If you already have an air purifier and it is too big for one room, use it. However, you might want to lower the speed of air change, meaning you have to set a lower number of air changes per hour.

Air change per hour is the rate at which the air purifier changes the air in the room. Some can do 4.8 times an hour, some higher and some lower than that.

Having a bigger air-purifying unit is not necessarily a bad thing. It just means it will work faster and do a great job. This can be a good idea when you have a room full of people or when your air is too polluted.

Another reason to run a big air purifier at a lower speed is to keep the noise level low. Large appliances make more noise.

Open the doors to purify more air

Another thing you can do when you have a large air purifier is to open all the doors to different rooms. That way, the unit can purify most if not all of the indoor air, despite it not being a whole house unit.

To do this, keep the ACH or speed at the highest. Remember, we said if you are using a large purifier unit in a small room, keep the ACH low.

If you need the same unit to purify the air in more than one room, keep the speed high. You should also place the unit in the room with the most polluted air.

If you can, place it as close to the door as possible so that it can access air from most of the rest of the rooms.

Run it for a short time

If it is large, it will do a faster job because it can draw a large volume of air. If you don’t believe this, you can calculate the volume of air in your room.

It is measured in cubic feet. The air exchange rate is measured in cubic feet per minute (CFM). This means the air volume that your appliance can move in one minute.

If your room is 10 feet high, 20 feet wide and 20 feet long, multiply these three measurements to find the total volume, which is 10 x 20 x 20. The answer is 4000 cubic feet.

A 1000 CFM system would take 4 minutes to cleanse all the air, or to exchange all the air in the room.

Usually, the recommended type of air purifier for your home air exchange needs would have a capacity of 200-500 CFM.

Modern air purifiers can show you when the air is polluted and it needs purifying. You can also get a smart unit with an air quality indicator so that you can know when the job is done.

Also, smart air purifiers can switch off and restart automatically depending on the quality of your indoor air.

Cons of an air purifier that’s too big for a room

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If you have an air purifier that is too big, there can be some disadvantages. Here are some of them:

High noise level

We have mentioned this issue a couple of times. Large electronic appliances make bigger noise. Thus, if you have a small baby, you might want to keep this appliance away from their room since they won’t be able to sleep.

If you are already thinking that your room is too small for your air purifier unit, well, it is. That’s why you will experience a higher noise level.

It will consume more electricity

Bigger electrical appliances consume more electricity, not always, but mostly true. You can read an article we published in the past on how much electricity an air purifier uses. While it is not much, it can hike up some more if you have to use a big unit.

Can an air purifier be too small for a room?

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Indeed an air purifier can be too small for a room. Hand in hand with this question, you might also ask: does air purifier size matter?

It matters a lot too. If possible, always buy a portable air purifier, humidifier or dehumidifier that has the correct space rating.

And it is not just about saving money on electricity, although it also counts. Rather, many factors come into play here. Noise level is one of them as well as efficiency.

Downright, we can tell you that it’s better to buy an air purifier with a larger space rating than with a small one.

If you have a small unit and you are using it in a large room, you will be overworking it. This can cause the unit to stop working, to overheat and to shorten its lifespan.

One thing we advise our readers is that when buying appliances, they should consider the features over the price.

In the case of an air purifier, ensure that you read its space rating in square feet, as well as the ACH. The Honeywell air purifier that we reviewed earlier has a space rating of 465 square feet and an ACH rate of 4.6 times in an hour.

Small air purifiers have small filters

At the end of the day, the size of air purifier HEPA filters matters. It is not possible to fit a big filter on a small appliance. Therefore, a small air purifier will have a small air filter.

Units that use HEPA filters are most appropriate in spaces they are rated for. If a manufacturer has rated their unit for 600 square feet, the filter fitted in the unit can handle that much air.

How many air purifiers do I need?

If you have a big house, you might wonder how many air purifiers you will need to clean all the air.

Unless you have a whole house air purifier, you might wonder how many portable units you need to clean the air in your entire home.

You can have small desktop units for small rooms or a couple of portable units that you can move from one room to another when need be.

If you live in an area with high air pollution, it is recommended you have an air purifier in the rooms where you spend most of your time. This is the living room, the bedroom and kitchen.

It is best to buy at least three portable air purifier units.

One large air purifier or two smaller ones?

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This goes hand in hand with the question of how many air purifiers you need. You might also wonder whether you should buy a big one that’s probably too big for many of your rooms or a few/many small ones.

Well, this is really not too hard!

If you can have a whole house air purifier, get it. It has a high initial cost of buying and installation. However, it is hard to integrate in old HVAC systems. Thus, most old homes might lack this one.

If this is the case, do not buy one large air purifier. Rather, get a few of them, say, at least three of them to run in the rooms where you spend most of your time.

To answer the questions of one large air purifier or two smaller ones … get the two smaller ones, or three, or even four.

Final thoughts on can an air purifier be too big for a room

An air purifier can be too big for a room, but it is not something you should sweat about. In any case, it is better to have a bigger unit than a smaller one.

If you can though, please get one that has the correct space rating! It is better that way because of the noise level and electricity consumption.

If you have an air purifier for 1600 square feet and your room is only 500 square feet, well, it is definitely too big. If you run it, it will still purify the air. However, it is unnecessary since a unit rated for 500 square feet can work well.

In addition to size, check what types of impurities an air purifier can remove, such as dust, mold, pet dander, dust mites and others.

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