photograph of the Sunlu Filadryer S1 used for drying 3D printer filament

Sunlu Filadryer S1 Review

Sunlu Filadryer S1 a filament heated enclosure, to maintain the quality of 3D filament. But let’s see how it performs with 60% humidity in this review.

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Dimensions:Width 100mm, Depth 271mm, Heigh 237mm.
Maximum Spool Size:Diameter 210mm, Width 85mm.
Suitable Filament Diameters:Up to 3mm.
Working Environment:20˚C-35˚C, 90% Relative Humidity. (So don’t use in a heat wave)
Adjustable Temperature Range:35˚C-55˚C.
Power Adapter:Input: 110-240V 50/60Hz. Output:24V 2A (±1.2V).
Standby Power Consumption:0.05W, 0.0021A.
Maximum Working Power Consumption:48W, 1.8A.
LCD:2″ (50.8mm) Backlight LCD.

First Impressions

closer view of the Sunlu Filadryer S1

Without a doubt the Sunlu Filadryer S1 is a reasonably smart looking tool to dry and reduce the humidity in a roll of 3D printer filament. However cosmetically I dislike the transparent surround of the LCD and would have liked an option to have purchased a black or grey version. Nonetheless the filament dryer from Sunlu is well moulded and opens and closes smoothly.

photograph inside the Sunlu Filadryer S1 with foam sides and filament rollers on bearings

Furthermore inside the Sunlu Filadryer S1 is a form of foam insulation on the side walls. Similar to that used to insulate the underside of a 3D printers heated bed. But without the silver foil. While the roll of filament sit on two roller bars that have bearings. However because the filament rods are wider than the inner diameter of the bearings and run the entire length. They bind slightly on the plastic housing. Consequentially it could cause issues with the stretching of TPU filaments. Naturally we will find out soon enough, as we will test printing TPU while housed in the Sunlu filament dryer.

Interestingly two 500g spools can fit inside the Sunlu filament dryer at the same time. Which is useful for the more expansive and moisture retentive filaments.

photograph of the top filament feeding hole on the Sunlu Filadryer S1

Additionally there is two holes to feed the filament through, one is on the top which is more suitable for directly feeding to the 3D printer on a worktop. While the second is more central and may be better for multi-filament uses such as the Prusa Multi Material 2 (MMU2s).

photograph of the bottom filament feeding hole with the rubber plug on the Sunlu Filadryer S1


photograph of the LCD on Sunlu Filadryer showing the current temperature

Finally the backlit LCD is large and fairly easy to read. Importantly the large buttons and easy settings makes the Sunlu Filadryer S1 easy to use. Additionally the filament dryer has an adjustable temperature range of 35-55˚C and a maximum drying time of 24 hours. Furthermore on first powering the Sunlu Filadryer S1, it starts with the default settings of a 6 hour dry time at 50˚C.

However the display is rather annoying to leave in the default display of the current temperature. Moreover it constantly flicks between the set temperature and the set temperature +1 ˚C at an interval of roughly half a second. Nonetheless if you long press the left button it will display the remaining drying time and is less bothersome.

LCD Menu

photograph of the LCD on Sunlu Filadryer showing the dry time

In order to change to length of time, press and hold the left button. Once inside the time (PV Time) menu, press the left or right button to increase or decrease the drying time. Finally to exit, hold down the left button until it returns back to the current temperature display (PV ˚C).

photograph of the LCD on Sunlu Filadryer showing the set temperature

Additionally to change the drying temperature of the filament, press either the left or right button. Furthermore within the set temperature menu (SV ˚C), the left and right buttons will adjust the temperature from 35-55˚C. Finally to exit simply leave the buttons alone for 3 seconds and it will return back to the current temperature display (PV ˚C).

Power Supply

photograph of the Power Adapter for the Sunlu Filadryer S1

Supplied with a convenient 24V 2A wall power supply, the cable takes up little space. However measuring at roughly a meter, the cable length isn’t very long or practical for many uses. Moreover it is a shame that Sunlu didn’t supply a DC extension cable with the dryer. Nonetheless a DC extension cable can be purchased and works well for getting that extra reach. Importantly on the Sunlu Filadryer S1 that I purchased, the external diameter for the DC plug is 5.5mm with an inner diameter of 2.1mm.

Affilate links below:DC Jack 5.5×2.1mm Extension
affiliate link: available at aliexpress
Available from AliExpress $0.77-$6.62
affiliate link: available at amazon
Available from Amazon UK £4.49
affiliate link: available at amazon
Available from Amazon USA $6.99


Recently I received a few rolls of PLA filament that have been completely saturated with moisture. Moreover what better way to test the Sunlu Filadryer S1 then with a filament that is showing a 60% relative humidity with a Hygrometer.

Drying filament

photograph of Hygrometer inside the SunluFiladryer S1 for testing Humidity

However I didn’t want to keep testing the filament until it was printable. Instead I wanted to see how well the filament dryer from Sunlu could reduce the relative humidity of the filament. A point of note, this isn’t a particularly scientific method. But it is a method that I use for my own DIY filament dryer and works well for me.

Furthermore below is a break down of time and measurements recorded, whilst using the recommended temperature by Sunlu for PLA. Importantly my simple hygrometer and temperature gauge was sat on top of the filament. Additionally the average ambient humidity was 40%.

chart showing the recorded measurements temperatures and humidity when drying 3D printer filament

There are a few things to take into consideration when viewing the above graph. Firstly the humidity (Blue Line) within the Sunlu Filadryer S1, as expected rose when powered down over night as it is not a sealed unit.

Secondly with a completely saturated roll of filament, it is best to set the temperature to the maximum. Moreover in this instance set at 50˚C (Green Line) the Sunlu filament dryer struggled in reducing the humidity below that of the room the filament dryer was placed in. Importantly the extra 5˚C introduced at the 64 hour mark, gave the filament dryer a little boost. But not much.

Introducing silica gel

Finally the key to drying out the filament came when a single 5g pouch of silica gel was placed inside the filament spool. Fundamentally it was this, that really got the moisture down to below 30%. Especially as it draws the moisture away from the warm damp air surrounding the roll of filament. Naturally you can add more silica gel sachets to speed up the further aid this process.

Affilate links below:Reusable Silica Gel Sachets Pouches
affiliate link: available at amazon
Available from Amazon UK £9.99 60 x 5 Gramm pouches
affiliate link: available at amazon
Available from Amazon USA $9.99 60 x 5 Gramm pouches

Before and After

photograph showing the effects of 3D filament that has absorbed to much moisture.

Sadly the picture I had taken just before placing into the Sunlu Filadryer has disappeared. However the above picture is the original I sent to the supplier of the filament, detailing the issue with this PLA. Importantly on the left was the previous roll of filament that was excellent. While on the right was the problem rolls with the 60% humidity issue.

photograph of 60% relative humidity filament dried for 90 hours in the Sunlu Filadryer S1

Furthermore the above picture is of a flow calibration after 90 hours in the Sunlu Filadryer S1. Clearly there is much improvement. But the roll still isn’t ready. Moreover the walls are not adhering to each other and require an additional 10˚C above normal todo so. While the small whips of filament are a little more frequent for this particular filament.


Without a doubt the lack of any connections for Bowden pneumatic couplers is disappointing. Furthermore with only one silicone seal supplied, it would have been nice if Sunlu supplied a spare.

Another disappoint of the Sunlu Filadryer S1 is the lack of a Hygrometer, to measure the amount of humidity. Especially as they are fairly cheap to implement and for me at least, a critical step in monitoring the drying out of saturated filament.

Finally the biggest disappointment is the amount of ambient humidity that enters back into the dryer. Especially when it stops heating. Personally I would have liked to have seen a silicone seal, with a fan to circulate the air. While featuring a solenoid controlled valve to vent the humidity once in a while.


Fundamentally the Sunlu Filadryer S1 on its own is not great at reducing high amounts of humidity from a spool of filament. Especially if the ambient humidity is also fairly high. While the Sunlu filament dryer may eventually get there, it is slow, and time consuming.

However for getting spools ready that are just showing signs of moisture retention, then the Sunlu Filadryer S1 is good. Simply set it for 6-8 hours and you are likely to be good to go.

Importantly despite the slight binding of the filament spool rollers, there has not been any noticeable issues effecting the flow of filament. Furthermore TPU again prints happily with no issues. However the rollers do appear to struggle a bit with a full roll of 1Kg filament, and this can be felt by hand when the filament is pulled. But it is not enough to have an discernible effect on the filament flow rate.

Affilate links below:Sunlu Filadryer S1
affiliate link: available at aliexpress
Available from AliExpress $69.99
affiliate link: available at amazon
Available from Amazon UK £69.99
affiliate link: available at amazon
Available from Amazon USA $79.98
Available from Sunlu $69.99 + Extra Automatic 10% Discount (at checkout)

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