Buying an Air Purifier for the Home
If you’re looking to address air quality in your home you first need to decide if you’re looking to improve air quality in
- your whole house or
- a single room
Improving air quality in a whole house
Houses, even small apartments contain a lot of air. A 1,000 sq. ft. apartment with 8 ft. ceilings contains 8,000 cubic ft. of air. A 3,000 sq. ft. home with 10 ft. ceilings contains 30,000 cubic ft. of air. That’s a lot of air!
So, if your goal is to purify all the air in your home we recommend the following strategy:
1. Get good quality reasonably high MERV filters for your HVAC system.
We recommend going all the way up to MERV 13 if you can. This will go a long way in lowering the overall particle concentration of the air in your home.
2. Put air purifiers only in the rooms where they will be most beneficial.
Most HVAC systems cannot accept an air filter better than MERV 13. HEPA is the equivalent of MERV 17. There are many other limitations to how well an HVAC system (even equipped with a high MERV filter) can purify the air in your home. We won’t get into them here but suffice it to say that an air purifier provides an entirely different level of air purification as compared to an HVAC system.
The problem is that air purifiers can be expensive – not only to purchase initially but also to maintain (primarily because of the cost of replacement filters).
So, if cost is a concern for you we recommend prioritizing rooms where an air purifier is going to be most beneficial. This includes rooms:
where you spend the most time
e.g. living room, bedroom
that generate a lot of particles and/or odors
e.g. kitchen, laundry room
Note that you also have the option of moving a single air purifier between different parts of your home. For example, you may want to operate a single unit in your living room during the day and in your bedroom at night.
In this case, you may feel like portability should be a concern for you as you make a purchase decision. The good news here is that this really doesn’t need to be a concern for you. Almost all air purifiers on the market are light enough and easy to carry.
3. Put individual air purifiers in all rooms
If cost is not a concern for you we recommend placing air purifiers in all of the rooms in your house. We still recommend installing a high MERV air filter in your HVAC system as it will essentially act as a pre-filter for the air purifiers’ HEPA filters – keeping them from “saturating” as fast and thus reducing filter replacement costs.
4. Install a whole house air purifier
As a last resort you can consider installing a whole house air purifier.
We generally do not recommend these units as
there are few options available
this forces you to choose the best of what’s available instead of the best air filtration possible. This also drives up the price of the units that are available. Because this is such a niche product manufacturers know this and therefore price units and replacement filters accordingly.
not as good filtration
many whole house units do not offer the same level of filtration as stand-alone portable units. Even the cheapest stand-alone unit can offer HEPA level filtration, which is to say, the ability to filter 99.97% of particles that travel through the filter. Most whole house units do not offer this same level of filtration.
most whole house units are extremely expensive to buy, to install, and to maintain. Again, this is a niche product and manufactures know this. These units are expensive. Installing them is expensive. Maintaining them – purchasing replacement filters for those units that have them – is expensive.
stand-alone units give you the freedom to choose where you put them and how you use them in different areas of the home. Maybe you spend the majority of your day (and/or night) in a particular room. You can pay to only purify the air in that room – by buying a single affordable air purifier for that room - and to the extent that you choose – by running it some of the time and/or on certain fan settings (to extend or decrease the life of the filter).
A whole house unit cleans the air in the whole house. You’re paying to filter the air (air purifier running costs and filter replacement costs) in all rooms – even if you may not need (or rarely need) to filter the air in certain rooms.
Improving air quality in an individual room
Improving the air quality in a single room is a much easier task than doing so for a whole house.
To start, first determine if the room can be sealed (can you close all doors and windows). If it can be sealed you’re in great shape. A sealed room is going to be able to get to much lower particle concentration than a non-sealed room.
The reason is simple: An air purifier processes a set amount of air. Sealing the room allows it to re-process the same air over and over again. As it does so, particle concentration will eventually reach 0 in a sealed room. In a non-sealed room new particles are constantly entering the room. The air purifier will never be able to achieve super low particle concentration in such an environment.
The bottom line:
In a sealed room - you’ll be able to achieve super low particle concentration which is the goal of running an air purifier in the first place. So prioritize sealing the room – leaving windows/doors closed as much as possible.
In a non-sealed room - do not expect this to ever be the case (achieving super low particle concentration), even if you’re constantly running even the highest CFM (output) air purifier in the room.
Second, determine the size of the room. A bit of good news here: We recommend the same “size” air purifier no matter the size of the room. So, the size won’t determine which air purifier you buy – just how you’re going to operate it.
No matter what the size of the room we recommend a top rated 250 CFM unit. These units provide the best combination of value, energy efficiency, and low noise output.
In a small room (up to 150 sq. ft.) – you can run a top rated 250 CFM unit on the 2nd highest speed. This equates to about 100 CFM of output which is sufficient for such a size room. On this setting these units will offer peak energy efficiency and will be very quiet as well.
In a larger room (up to 300 sq. ft.) - you will need to run a 250 CFM unit on its highest setting to get to super low particle concentration in the room and then you can set it to its 2nd highest setting to maintain that low concentration. Do note though that particle concentration in the room will slowly creep up if you leave the unit on the 2nd highest setting for too long. So we recommend that you run it on its highest setting as much as possible.
In an extra large room (well over 300 sq. ft.) – we recommend you run multiple 250 CFM units. Doing so will provide superior coverage in the room at a lower price than buying a single higher CFM unit.
3 types of contaminants you may need to remove from the air in your home
Off gassing VOCs
New construction houses, certain flooring, and certain furniture can off gas (release) VOCs. If your home is new construction or if you have off gassing flooring or furniture in your home prioritize an air purifier with a good carbon filter. The best affordable option currently on the market is the Winix 5500-2.
Any other VOC source
If there are other sources of VOCs in your home - eg. cigarette or wildfire smoke– we also recommend a unit with good gas filtration. Again, the Winix 5500-2 is our recommendation. If the problem is especially egregious we recommend the Austin Health Mate. It’s quite a bit more expensive than the Winix but will provide the best gas filtration possible in an air purifier.
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