Too Lazy; Didn’t Read Version :
While neither one of these two were perfect by any stretch of the imagination, just don’t buy the S2 even if it is discounted and you have to pay full price for the Creality Space PI. The difference in performance vs value is huge.
Disclaimer: Both of these devices dried filament.
What follows is my opinion based on measurements and a table of what I found to be important to me personally. YMMV
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Background: make versus buy and out of box impressions
Background
I wasn’t a big fan to start with of the idea of having yet another bulky item on my desk. Plus, one can build a very effective dryer just using the box the filament came in and the heatbed, as noted in this recent post. However, I got tired of tying up my printer bed and wanted more convenience where I could set it and forget it. Last but not least, if I am going to buy something purpose-built, it had better be better performing and cheaper than what I can build myself. What was disappointing is that nobody bothered to measure actual temperatures of these filament dryers. 
The high cost of many dryers in 2023, exceeding $100, deterred me from purchasing one. That’s more than the cost of 6 spools of PLA and 1/6th the cost of my P1P. Additionally, it wasn’t until recent experiments that I became convinced that I had a personal use-case justifying the investment in a dedicated dryer. PC filament changed my mind as I showed side by side results in this post.
When researching dryers, I encountered a plethora of truly awful advice on YouTube—misleading gimmicks and a lack of scientific rigor. So, as usual, I had to verify things for myself.
My philosophy on most electronic appliance purchases is simple: function over form. I’m not swayed by aesthetics; I want practicality. In fact, gimmicks are a turn-off for me; they feel patronizing and insulting to my intelligence. That’s why I was initially drawn to the original Sunlu S1 design. It had a straightforward button interface, a clear lid, and a simple rectangular shape. If only Sunlu had updated that design with improved temperature control, better air circulation, and a clearer display, they would have had a winner in my eyes. But no! They had to prioritize aesthetics over functionality.
On March 1st, when comparing prices on Amazon, there was a $16 or 25% price difference between the new Creality Space PI and the Sunlu S2. So, I opted for the S2. Despite its slightly lower(-5c) maximum temperature, I couldn’t justify the higher cost of the Creality model even though my principle justification was for filaments such as PC and ABS drying where the higher operating temp would have been an advantage.
Upon setting up the S2, I immediately noticed issues. Firstly, it was very unstable, with a high center of gravity that worsened with a full spool inside. Finding multiple stand solutions on printables.com confirmed that I wasn’t alone in recognizing this design flaw. It also tipped over when my printer was shaking my already unstable table, not a good start.
On-screen Temp reporting
TEMPERATURE REPORTING
As I set up the device and attached thermocouples to a sample spool, things quickly went downhill. Temperatures fluctuated wildly, varying by as much as 15°C throughout the chamber. However, the final blow came when none of the temperature readings came close to the advertised 65°C or what was displayed on-screen, not even with my sensors placed next to the chamber’s sensor input. I gave the dryer every advantage but I could not measure a single spot that hit the advertised or displayed temps. This discrepancy led me to believe that Sunlu falsifies their specs and temperature readings, as there’s no other explanation for such a drastic difference. Despite using six different thermometers and repositioning the sensors over two weeks of testing, the measurements remained consistently off.
Feeling thoroughly cheated, I attempted to contact Sunlu tech support about a possible defective unit, but received no response.
By this point, my buyer’s remorse was simply too deep and unrecoverable and I had already resolved to return the S2 through Amazon. However, just before doing so, I stumbled upon a deal that significantly reduced the price of the Creality PI, narrowing the cost difference to less than 10%. This made the Creality PI seem more worthwhile, but I remained skeptical given Sunlu’s misrepresentation and the common practice among Chinese manufacturers of misleading consumers. In short, would Creality be any better?
Product Review Using Personal Preferences
Before I shipped the S2 back and uncertain whether my emotions were clouding my judgment, I compiled a list of criteria important to me and scored each category from -2 to +2. For a +2 rating, the product had to exceed my expectations, while a -2 rating indicated misrepresentation or truly poor performance. I then did a thorough bake-off based on my personal preferences.
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| Score | Personal Subjective Meaning |
|---|---|
| 2 | Exceeded expectations |
| 1 | Met expectations |
| 0 | Neither good or bad |
| -1 | Disappointing |
| -2 | Awful |
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| Category | Sunlu S2 | S2 Comments | Creality Space PI | Creality Comments |
|---|---|---|---|---|
| Max Temp Advertised | 65c | 70c | ||
| Max Temp Reached | 60c | 70c | ||
| Price Advertised on Amazon | $70 | $86 | ||
| Price Paid on Amazon | $60 | $66 | ||
| Display | -2 | Very hard to see, backlight does not stay on | 1 | Great contrast and color, would be better if it had antiglare surface |
| Controls | -1 | Not responsive touch screen must hit multiple times | -1 | Not responsive touch screen must hit multiple times |
| What’s wrong with just simple buttons | ||||
| Clear View of Spool? | -2 | Blocked in top-down view, Unnecessary Smoked glass | -1 | Unnecessary smoked glass |
| Temp reached advertised levels? | -2 | Really far off and uneven | 1 | Performed as advertised |
| Temp Accuracy | -2 | Totally inaccurate | 2 | Very Accurate |
| Evenness of Drying/Heating | 0 | Very Uneven ±15c throughout the chamber | 2 | No significant or measure hot spots |
| Humidity Sensor Accuracy | -1 | Off by 15% | -1 | Off by 10% |
| Internal Humidity Regulation | -2 | Must lift cover periodically to release moisture | 2 | Even temps throughout cycle |
| Lid Spool Accessibility | 1 | Good access | -1 | What were they thinking? |
| Power Supply | -2 | Wall-wart, horrible waste of space and dangly cord | 2 | Integrated- 2 wire power cord- excellent. |
| Drying | 0 | Must lift cover periodically to release moisture | 1 | Does the job well |
| Spool Path | 1 | 2 Paths top only | 0 | 1 path top only |
| Overall Size on Table | 1 | Just the right size | -2 | Hinged lid makes it unwieldy |
| Stability on Table | -2 | Tips over during heavy printer vibration | 0 | Stable |
| =========== | ==== | ==== | ||
| Total Score | -13 | 5 |
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Power Cords and Power Supply
Sunlu, Wall-Wart??? Really? in 2024? This also limits where one can place the device since the power plug is inconveniently placed on the side.
Creality, internal power supply with power switch(NICE!!!) 
The Lids? WTF??? Creality Space PI means it takes up more space!!!
The Creality lid is awful, 
there is no justification for this swinging back so far increasing the overall depth to 23". It forces one to reach 2 feet back to grab the lid and takes up unnecessary space. They almost had it right if they had just made a lid stop, a real missed opportunity.
While the S2 Lid completely was obscured by the second heating element and the filament spool was blocked so you wouldn’t know what was in there without opening it up. As if the smoked glass wasn’t enough.
Why can’t these companies just use clear acrylic?
Display quality
Display
Creality emerges as the clear winner when it comes to the display. Adding to that, Sunlu’s failure to allow the backlight to remain on creates a frustrating experience, requiring users to manually activate the panel to view the display again. In contrast, Creality keeps the display illuminated after the cycle ends. Additionally, the S2 features a seemingly pointless LED ring, which, in my opinion, is merely a gimmick and an annoyance I quickly disabled. It would be more valuable if it, for example, changed color or pattern to indicate certain statuses, but it’s evident that it serves no practical purpose and is simply a light show.
Actual temps versus what was on the display
Air Circulation and recorded temps using a calibrated thermometer
Both of these were taken at the same time and only provide a visual representation of where the heat was distributed. Both had empty cardboard spools inside and both were allowed to reach temps after 20 minutes. The only conclusion one might draw is that perhaps the smoked glass on both minimizes the escape of radiant heat. That is the only justification I could find for using smoked glass.
S2
Creality
Both Side by Side
The S2 says it now has air circulation and you can indeed hear “a fan” working, but however they implemented it, it simply does not even out the temp circulation which is a concern given that a low temp filament or spool could be easily warped or the filament fused if unevenly baked.
The Creality on the other hand was the clear winner in this category. It has a well placed circulating fan and their ads make a big deal about this. I will say that the Creality feature lives up to the hype. For me, this was the clincher because after all, if a dryer can’t meet the temps, what’s the whole point?
Here they are side by side using a Type K plug thermistor thermometer. The thermistor probe was placed inside the filament hole near the spool hub. Both had cardboard spools and were allowed to reach temp
As a final sanity check I used a food thermometer. Why? Because this thermometer can be trusted for two reasons, it can be calibrated and it can be verified by simply measuring boiling water and/or melting ice.
Sunlu
Creality
Relative Humidity measurements a wasted effort
Relative Humidity measurements a wasted effort
As with many experiments, I delved into a rabbit hole trying to ascertain how to accurately measure temperature and RH. I gained valuable insights, and since this post is already lengthy, I’ll mention that there are only two designs for RH sensors, both of which are inherently inaccurate without calibration. Moreover, both sensors eventually oxidize and degrade over time, explaining why most of my hygrometers fail after only 6-18 months of use.
However, I also learned how to calibrate humidity and utilized the Salt Brine method to demonstrate the inaccuracy of all my hygrometers, as well as to measure the discrepancy in reporting relative humidity (RH) between both dryers. Yet, ultimately, I realized that without the ability to control RH, as would have been beneficial in the S2, there’s little point in displaying it if it cannot be calibrated either. In my opinion, this renders it a mere waste of display and components. Furthermore, it became evident that both dryers were based on the exact same design and likely shared components, given the similarities in display and controls. They either mimicked each other or another source.
Conclusion - Either one will dry your filament
Conclusion
While both companies get failing grades for putting form over function with respect to case designs(smoked glass that obscure viewing what filament is inside as well as foolish stylish shapes), both will dry filament. So if you already have an S2, the Creality is not worth upgrading to. Creality does get bonus points for “truth in advertising”
However, Sunlu gets real negative marks in my view, they had an opportunity to address my concerns when I emailed them two weeks ago but they made a choice not to respond. They also made a choice when they posted false information on their site and product literature. So on those two items alone, I have some real bias against buying anything they make that is hardware related. If you lied to me once, how can I possibly trust anything you say?
If you didn’t figure it out yet, the S2 was shipped back to Amazon for full credit.
