CO2 Click Model F Review – Portable CO2 Monitor

Over the past two years, I’ve reviewed three CO2 Click sensors, and today, I will add the fourth to that list. The CO2 Click Model F is a lower-cost, portable CO2 monitor that sits below the connected and more expensive Model C (and Model D) in this company’s monitor lineup. It achieves its lower price by dropping some features, such as the web dashboard, and by changing the sensor from the dual-beam NDIR SCD30 to the photoacoustic SCD41.

Despite the lack of connectivity that makes other CO2 Click monitors, such as the Model C, Model G, and Model X, among my favourites, the Model F shares the other key strengths that make me particularly appreciate CO2 Click monitors. Namely, although cheaper, it doesn’t drop the quality of the sensors and still uses a fantastic and well-trusted sensor from Sensirion. While it isn’t the dual beam NDIR sensor from other CO2 Click monitors, it is still a very high-quality and reliable sensor.

This use of high-quality components alongside the fantastic dashboard (which doesn’t apply in this case) is what has kept me coming back to CO2 Click monitors, and I’m curious to see if the standalone Model F can still be a great monitor, even with one of these strengths lacking. Of course, it does make up for it by being a significantly cheaper device than the other monitors in the range.

That leads me to the key question I want to answer in this review: Does the lower price of this carbon dioxide monitor justify the removal of web dashboard connectivity, or is the remaining strength of high-quality components not enough? Furthermore, how does this CO2 monitor stack up compared to other affordable carbon dioxide monitors? Enough said, let’s dive in!

This post contains affiliate links. For more information, please refer to my affiliate disclaimer. I was sent a product for review, but the article is not sponsored. All opinions expressed in this post are my honest thoughts. I only recommend products that I genuinely believe in.

Information on this blog is for informational purposes only. Readers are encouraged to confirm the information herein with other sources. Furthermore, this information is not intended to replace medical advice from professionals. This website assumes no responsibility for the accuracy of the information, and information is subject to change without notice. Devices mentioned on this website are not medical devices and do not guarantee protection.

Accuracy & Sensor

Despite being a lower-cost CO2 sensor than its more feature-full siblings, the Model D and Model C, the Model F does not cut corners regarding accuracy. Inside this monitor, you will find one of the most trusted consumer-grade CO2 sensors on the market – the photoacoustic NDIR SCD41 from Sensirion. This is the same sensor in monitors from the incredibly tiny AirValent CO2 monitor to the Qingping/SmartAir CO2 monitor. As an integrated sensor, the SCD41 monitors:

• Carbon dioxide
• Temperature
• Relative Humidity

These are the standard parameters we expect within most carbon dioxide sensors (unless the monitor uses a second sensor for environmental metrics), and the only notable omission is an atmospheric pressure sensor. While this sensor is also lacking in most other sensors in this price range (minus the brand-new SenseAir S88), it’s worth mentioning because it does play an important role. Anyway, more on that soon.

The SCD41 is currently a very popular sensor due to its compact size. While it’s still an NDIR sensor (the gold standard for CO2 monitors), it isn’t a traditional transmissive NDIR sensor like the ones you will find inside the Aranet4 Home and even the other CO2 Click monitors. Instead, it’s referred to as a photoacoustic NDIR sensor, which has a few key advantages and disadvantages. Primarily, these sensors are tiny as they don’t rely on lasers that must be placed a minimum distance apart. This allows the SCD41 to be much smaller and allows for the miniaturisation of CO2 monitors.

However, there are some disadvantages, too. For example, while similarly accurate to transmissive NDIR sensors, photoacoustic NDIR sensors have some caveats when calibrating them, and they should be calibrated in a sheltered area with minimal airflow. On top of that, they seem to have issues regarding cooler (or hotter) temperatures. While it’s far from conclusive (and I thought it was due to the monitor I was testing at the time rather than the sensor itself), I’ve found that photoacoustic sensors appear to be more influenced by temperature than their transmissive counterparts. However, this likely won’t have much impact on real-world usage.

Anyway, I will discuss these caveats further later in this section. The most important takeaway is that the SCD41 and, by extension, the CO2 Click Model F provide similar performance to the best consumer-grade carbon dioxide monitors, such as the Aranet4 Home and even its bigger sibling, the Model C (which uses a much more expensive sensor). After using this sensor extensively and after comparing Model F to both the Aranet4 and Model C, I conclude that it is accurate when calibrated in the same conditions. However, it’s important to keep in mind that there is a 400 ppm baseline on the Model F. In contrast, on the Aranet4 and some other devices, the baseline is a more accurate 420 ppm, meaning you should remember there is about a 20 ppm offset on this device compared to those devices and likely a 20 – 30 ppm offset compared to the actual CO2 concentration which you can check here.

Both the SCD41 and Model F perform well when it comes to accuracy, and they can be trusted. However, as I mentioned earlier, there are a couple of caveats that I want to mention. Firstly, I recently discovered how much of an impact altitude (atmospheric pressure) can have on carbon dioxide monitor and their readings. This shouldn’t impact most people, but if you live at a higher altitude, the readings from non-corrected sensors quickly become inaccurate. For example, below is a graph comparing my Model F (uncorrected) to the Aranet4 Home (corrected) at 1500 metres altitude.

As you can see, the two monitors provide very different readings even when calibrated under the same conditions. This is because the SCD41 (and most CO2 sensors) don’t have built-in air pressure sensors to account for differences. On the other hand, the Sunrise sensor in the Aranet4 Home does, and it will automatically account for these differences. Is this a big deal? For most people, no. However, it’s something to consider if you live significantly above sea level. The above graph shows an extreme difference, and most of the population won’t be impacted as they live below 1000 metres.

It’s also important to note that outside of a few higher-end CO2 monitors, no consumer-grade monitors automatically account for air pressure. Furthermore, it’s only something I recently became aware of, so I need to go back and update prior reviews accordingly, as this applies to nearly every monitor I’ve reviewed on this website. All of this is to say that this isn’t an issue with the Model F exclusively, but with most CO2 monitors and it’s something you should be aware of.

Another consideration I alluded to is that the SCD41 also seems to have some fluctuations due to extreme (or not so extreme, depending on where you live) temperature. Above is a graph which shows the Aranet4 Home and the Model F recorded concentrations when they were in an airtight container in the fridge. We expect a consistent drop in CO2 concentration similar to what the Aranet shows. However, instead, we see increasing and decreasing recordings when the temperature rises and falls. I’ve also seen similar behaviour with this sensor at high temperatures (35 degrees Celsius and above).

So, what does all of this mean? Should you avoid the SCD41 and the Model F? No, I don’t think so. It’s a fantastic sensor and a great monitor. However, the shrinking of the sensor size did bring about some caveats, and it’s important to be aware of these so you can get the best experience from your carbon dioxide monitor. The one exception I would put forward is that if you do live at a high altitude (over 1000 metres), you will either want to look into adding the altitude value to the sensor manually (there is open-source firmware available, so this is possible) or look at getting a monitor with an altitude sensor built-in like the Aranet4 Home.

Regarding temperature, the variations are small enough that you shouldn’t notice much difference – especially when it comes to the actions you should take (as 1000 ppm and 1100 ppm typically require the same actions to be taken, as do 3000 ppm and 3200 ppm). It’s also worth mentioning that these issues are only experienced under quite harsh temperatures, which shouldn’t be found in many indoor locations where you will usually use the monitor. As such, I don’t think this is an issue either – just something to be aware of.

Regarding accuracy under most conditions, the Model F and SCD41 are great performers and provide accuracy similar to that of the best monitors and sensors on the market because they are one themselves. Also, in this price bracket of carbon dioxide monitors, you’ll be hard-pressed to find anything better as most monitors use the same sensor or the SenseAir S8 (which also doesn’t have an air pressure sensor built-in).

Design

The Model F, even on the official website, is compared to a stick of bubblegum, and there is no better comparison regarding the shape and size of this device. Compared to other, typically square monitors, the Model F has quite a unique form factor that easily stands out. Overall, I prefer it too, as this long shape makes it very pocketable, and it feels a lot less cumbersome to carry because of this.

When the device is face-up, you will be presented with one button next to a small screen. This button is essentially the ‘home’ button, and it’s how you will turn the screen on to see the current CO2 concentration. After you press the button, the screen will stay on for long enough to check any information you need before it turns off again to conserve battery life. I would have preferred a small e-ink screen that could convey the carbon dioxide values while preserving battery life, but I understand these are more pricey and are challenging to find in such small sizes.

Since the device isn’t symmetrical and the screen only has one upright orientation, you will need to use the device with the button and screen on the left. This is far from a big deal, but it did mean that I would often need to turn the device around after pulling it out of my pocket (I am right-handed, and the device feels more natural to hold in my left hand).

Opposite the screen, you will find vents on all sides but the bottom of the device. These allow air to flow through to the sensor and ensure the device can provide accurate readings. As with all CO2 monitors (and air quality monitors in general), the device isn’t waterproof, and you will want to keep it safe from water. Again, this is consistent across all CO2 monitors and isn’t an issue that is isolated to the Model F. However, it is important to keep in mind.

Interestingly, you can see the sensor through the vents, and it’s truly amazing how small it is (please see the picture in the accuracy section for a size comparison!). In fact, when you see how small the sensor is, it’s apparent how much this photoacoustic sensor has changed the game through miniaturising NDIR sensors. That said, we now need to wait for other technology, such as batteries, to catch up to get even smaller monitors (and, hopefully, one day, the ability to integrate these sensors into other devices like watches).

Anyway, I digress. Talking about the battery, it’s worth mentioning that the battery life is around 15 hours. While this means it won’t last a full day, it is more than enough to get through a day of work or school, and I appreciate having this decent battery life. It’s significantly better than devices like the Vitalight Mini CO2 Detector, but it also falls short of other devices that rely on double A batteries.

On the sides of the monitor, you will find two buttons – one enabling the WiFi hotspot (it will not turn on unless you press this button) and another that doesn’t seem to have a function. I can only assume this second button is firmware-related, but it’s hard to know for sure. Either way, the buttons you will find yourself regularly using are the ‘home’ button and the WiFi button.

The only other feature of note on this device is the USB Type-C port found on the end of the device near the main button. While it should be expected at this point, I’m glad to see Type-C used, and a surprising amount of monitors still (disappointingly) use the older micro or even mini USB standard, which is very outdated. I wish I wouldn’t be used anymore… Looking at you, Amazon and PurpleAir!

Now that we’ve looked at the design, I want to take a step back and discuss the build quality. You’re likely already aware, but if not, the CO2 Click devices are built by hand using 3D-printed parts. Therefore, while their build quality is generally good, and I don’t have anything to complain about except minor things, you will likely notice some imperfections with the construction of the device. For example, my device’s top piece and bottom plate don’t quite line up when I look closely.

Is this a deal-breaker? Far from it. I would happily take these minor imperfections that don’t impact my day-to-day usage of the device if it means supporting a smaller air-quality monitor maker, which, in this case, it does. However, it is important to remember this when you purchase a monitor from CO2 Click. I’ve also been using CO2 Click monitors for a couple of years, and I’ve never had anything more than minor issues with the build quality.

Connectivity

When it comes to Model F, connectivity is an interesting topic of discussion. Firstly, it’s important to note that this monitor is clearly designed to be standalone. While it offers some connectivity, the monitor is primarily a device intended to be used by itself rather than with a smartphone accompanying it. This can be a big boon, depending on how you want to use the monitor.

So, why do I say this is primarily a standalone monitor? Well, while the monitor does have WiFi, you will need first to enable the hotspot on the device (by pressing the side button) and then connect to it either by scanning the QR code on the device’s screen (which I’ve found only gets picked up by my phone sometimes) or by connecting manually to the hotspot as you would usually connect to a WiFi network with your phone or computer. Once connected, you must navigate to 192.168.4.1 to access the device’s settings.

This process takes less than 30 seconds, but it means that you’re not always connected to the device; therefore, there is no web dashboard or app to accompany this device. However, you can do a few more advanced functions by connecting to the device’s hotspot. From here, you can export data, calibrate the device, and more. While simple, this interface houses all the settings essential for a carbon dioxide monitor like this.

The monitor will retain 96 hours (four days) worth of data, which is stored in one-minute intervals on the spreadsheets. Conveniently, this data is super easy to download, and I haven’t had any issues exporting the data to either my computer or phone for graphing and other manipulation. It’s important to note, however, that once 96 hours have elapsed, you will lose any data that you haven’t already saved.

I’m okay with this compromise as this is an ‘affordable’ monitor with limited internal memory. I’m glad to see that data can still be exported, and I don’t think that losing more than four days old is a big issue. Perhaps the period could have been extended to one week (I would be okay with dropping the intervals to five minutes instead of one to accomplish this), but four days seems acceptable to me.

On top of this, you can also change the date and time on this site. This is one big issue I have with the Model F – when the battery dies, all time settings are lost. Many computers get around this by having a replaceable battery on the motherboard, and I wish the Model F also had some tiny battery in it to retain time and date information even through power loss. Unfortunately, this isn’t currently possible on the Model F, though.

This means that you will likely find yourself updating these date and time settings quite frequently unless you are very good at ensuring the device never runs out of battery. This won’t be an issue if you’re regularly using the device and charging it every night. However, I do wish the time and date data were kept even through the times that I forget to charge the device or am travelling and don’t have time to ensure it remains powered.

Finally, through this web page, you can also calibrate the device. This is as simple as pressing the button, placing the monitor outside, and leaving it for three minutes. Overall, the calibration process is exceptionally straightforward, and I have never encountered any issues here. That said, as discussed in the accuracy section, there are some things to keep in mind when calibrating the SCD41 photoacoustic sensor (place the monitor outside, but not in the way of strong airflow). Still, these don’t relate to the software experience.

It’s also worth noting that you can update the Model F firmware by downloading the file from the product page and then selecting it through the web page. I haven’t yet needed to do this as there haven’t been any firmware updates since I’ve had the device, but it’s nice to see the option to update the monitor is there – even if it is a manual process due to the lack of connectivity for OTA updates.

As you can tell, the connected side of this monitor is quite bare, and it’s clear that the Model F is intended to be used on its own. Luckily, it is quite strong in this regard, and I rarely want or need to connect the monitor. When I do connect it, it’s usually either to calibrate the device or export data, which, outside of this review, I wouldn’t be doing too often anyway!

If you are looking for a monitor that allows you to check concentrations via an app or dashboard, you will be better suited with something like the Model C or the SmartAir/Qingping CO2 monitor. If, however, you are looking for the opposite and want a device that doesn’t need to rely on a smartphone or other form of connection, the Model F is a fantastic monitor, and it may well be one of my favourite ‘dumb’ monitors.

Pricing & Competition

The CO2 Click Model F sells on the CO2 Click website for 129 CAD, which, at the time of writing, is around 95 USD. At this price, it’s not cheap, but it is among the more ‘affordable’ carbon dioxide monitors in the $50 – $100 range, which includes options such as the SmartAir/Qingping CO2 monitor and the Qingping Air Monitor Lite. In this price range, it’s significantly cheaper than the ‘premium’ options such as the Aranet4 Home, INKBIRD IAM-T1 and even the Model F’s bigger sibling, the Model C, but more expensive than devices like the Vitalight Mini CO2 Detector.

I’ve already posted on the best affordable CO2 monitors, and I recommend checking that out if you want to learn more. However, in my mind, it comes down to this: Within this price range, the CO2 Click Model F is the best standalone portable CO2 monitor. If you don’t want a monitor that must always be tethered to your phone or a portable battery, the Model F is a fantastic choice due to its good sensor and pocketable form.

However, suppose you need a connected monitor that allows you to see the current carbon dioxide concentration on your smartphone or laptop. In that case, you will want to look at another monitor, such as the SmartAir device (although that’s also not perfect when it comes to connectivity due to its reliance on WiFi as opposed to Bluetooth). Alternatively, if you don’t mind something that is less portable due to size and battery life but measures more pollutants, the Qingping Air Monitor Lite is worth looking into.

At less than $100, this device is significantly cheaper than the ‘premium’ monitors mentioned above, and I see no need to upgrade to those monitors unless you really value connectivity. I do see advantages to having connectivity, and I personally appreciate this aspect of my other CO2 Click devices, but I also appreciate not needing yet another app on my phone and the simplicity of a standalone monitor.

Of course, since the Model F firmware is open source, it also has one unique advantage that none of the other monitors I’ve mentioned have: the ability to make the changes you want to the firmware – assuming you have the knowledge. This is potentially very powerful, allowing you to edit the Model F however you want. In the right hands, this is a massive advantage of this monitor!

Conclusion

The Model F is a carbon dioxide monitor that departs from CO2 Click’s normal strength of fantastic WiFi connectivity but keeps my other favourite trait of always using high-quality sensors. In departing from using a dashboard, the monitor has gone completely in the opposite direction and has become a great standalone monitor that doesn’t require any connectivity at all.

This bold choice has turned out well, and I like how this monitor functions as a device that doesn’t require me to bookmark another website or add another app to my home screen. At the same time, the device doesn’t drop functions that are more easily done through an app or webpage, as it still has its own local portal. While it is simple, the required features are here, and I appreciate the fact that data can still be exported.

However, the lack of connectivity will be the biggest downfall for some people. At the end of the day, it really comes down to whether or not you want a device that works well by itself or a device that provides more detailed data, analytics, and settings but that requires either a WiFi or Bluetooth connection. I think there are strong cases for both kinds of devices, and there is no right or wrong answer – it just depends on your use case.

When it comes to accuracy and performance, the Model F does a great job, and this monitor uses well-trusted sensors from a brand with a good reputation. It’s also a sensor that has now been on the market long enough to have research and studies behind it showing its accuracy. Therefore, if you want an accurate, portable and standalone monitor, the CO2 Click Model F is definitely worth looking into!

CO2 Click Model F FAQ

CO2 Click Model F Review - Portable CO2 Monitor

The Model F from CO2 Click is a carbon dioxide monitor that functions best as a standalone, untethered monitor. It uses an accurate SCD41 sensor and is extremely portable and compact.

Product Brand: CO2 Click

Editor's Rating:
4

Pros

• Accurate SCD41 sensor
• Portable size & shape
• Very easy to use
• Allows for data exporting
• Manual recalibration (and no automatic calibration)

Cons

• No connectivity
• Relatively expensive
• Short battery life