SUNLU FilaDryer S4 Review

The SUNLU FilaDryer S4 scores 7.0 out of 10 here: it is a roomy four-spool dryer at $116.99 on the SUNLU store (price read Oct 23, 2026), held back by uneven heat and a lid that does not seal. Buy it if you print PLA, PETG and TPU on one or two printers and want to dry several spools at once. Skip it if you dry nylon or need a sealed box that doubles as storage.

This review is researched, not tested in our own lab. It rests on the brand’s published specs, the federal recall database and named third-party reviewers, as explained on How we score. For other models, see our best filament dryers list.

Verdict: is the SUNLU FilaDryer S4 worth it?

Yes for capacity and price, with one honest warning about heat. The brand lists 70 C maximum, a chamber balanced within plus or minus 3 C, and room for four 1 kg spools. Reviewers confirm the capacity. The evenness claim is where the evidence turns against the brand.

• Price: $116.99 for the black US-plug unit with no bundle. The store strikes through a $139.99 list price. Bundles with one to three random PLA spools cost $126.99 to $140.99.
• Heat: Makers101 reports a thermal-camera test with about a 10 C gap between the hottest and coolest parts of the chamber.
• Humidity mode: The Gadgeteer saw the unit start at 30% humidity and stop at 25%, matching the brand. That reviewer had no external humidity sensor, so this only shows the dryer’s own display agreeing with the brand.
• Recalls: A CPSC SaferProducts search for “filament dryer” and for “SUNLU” returned no recall on Oct 23, 2026.

Design and setup: what do you get in the box?

Picks here come from published specs, certification databases and named third-party measurements, not from our own lab, and the setup notes below come from the SUNLU product page and named reviewers, not from a unit we handled (method). The page lists a drying box, one power adapter, one user manual, two 100 cm PTFE tubes and four 8 cm PTFE tubes. The interior is 450 x 210 x 211 mm, and the outer size is 516 x 278 x 350 mm in the packaging.

1. Set the box on a flat surface with clearance on the sides, since two fans sit on the left and right walls and a third sits at the bottom, per the brand page.
2. Load up to four 1 kg spools. Creality Experts reports that two 1 kg spools fit per side and a 3 kg bulk spool does not.
3. Run a PTFE tube from one of the eight filament holes to your printer if you want to print while drying. 3DWithUs says a sharp bend at the printer can snap brittle filament such as wood PLA.
4. Pick a preset. The brand page says it ships with PLA, ABS, PETG, TPU, PA and PC presets.

3DWithUs also reports one top lid arrived loose and needed a manual fix, and that desiccant for storage use is not included. That is one reviewer’s unit, so treat it as a possibility, not a pattern.

How does the SUNLU FilaDryer S4 score?

It scores 7.0 out of 10 using the weights below, and every subscore is explained after the table.

• Heat (6.0): 70 C is enough for PLA, PETG and TPU but short for nylon. A Reddit owner who has two S4 units and a Creality Space Pi X4 notes the Creality reaches 85 C. Creality Experts also found its outside sensor read 49.5 C when the dryer was set to 55 C. That gap may come from sensor placement, as the reviewers suggest.
• Capacity (8.5): Four spools and eight feed holes. The loss is for bulk spools.
• Feed and display (7.5): Humidity control works as described. The display ran conservative, showing 18% to 19% when Creality Experts’ sensor read as low as 14.3%.
• Build (6.5): The brand cites triple protection and a UL Solutions file number (KSOT.E537567). We did not verify that file. No lid gasket, per Makers101, and one owner thread reports an Er3 fan-error shutdown.
• Cost (7.0): See the math below.

The Practical Math: what does it cost over three years?

The S4 costs about $176.56 to own for three years, and electricity is a third of that.

One hour per day of full-rated power equals roughly one six-hour drying cycle every six days. Gambody measured about 400 W while heating and about 80 W while holding temperature, so a run that mostly holds will cost less. Desiccant for storage use is optional and left out of the total. Makers101 showed an Amazon listing at $99.44 on Oct 16, 2026, so check retail prices before you buy.

Alternatives: what else should you compare?

Two models come up repeatedly in owner threads. Neither was priced or scored for this article, so check current prices and the best filament dryers list.

• Creality Space Pi X4: Reddit owners describe two separately controlled chambers and an 85 C ceiling. One poster said it cost $159 in Dec 2025, which is the poster’s figure, not a current price.
• Sovol SH03: A commenter in an r/3Dprinting thread says it has an automatic dehumidification system, and the original poster called it lower in price than the Creality. We have not read its specs.

Who should skip the SUNLU FilaDryer S4?

Skip it if you dry nylon, PC or other filaments that need more than 70 C. Skip it if you want airtight storage, because Makers101 reports the lid has no gasket and an owner on r/ElegooCentauriCarbon posted a self-designed printable gasket for the same reason. Skip it if you work in a quiet room: The Gadgeteer measured about 62 dB in a 38 dB office, and Makers101 cites a 45 dB reading from a different tester at half a meter. The two figures use different methods, so read them as “audible,” not as a comparison.

FAQ

What temperature should I use for PLA and PETG?

Makers101 reports that Aurora Tech soaked PLA, PETG and TPU at 85% humidity for a week, and that print quality improved sharply after six hours at 50 C. That is one tester’s run, relayed by Makers101. The same article warns that the PETG preset fused four rolls into a block for another tester, and advises setting the temperature 5 to 10 C below any preset.

Can I print directly from the S4?

Yes. The brand page lists eight filament holes and supports feeding up to four printers. Mind the tube bend at the printer, as 3DWithUs warns.

Does the S4 keep filament dry as storage?

Not well. With no gasket, the lid does not seal when the power is off, per Makers101. 3DWithUs says storage use needs desiccant and plugs for the feed holes.

Is the S4 safe to leave running?

The brand lists three protection layers and a UL Solutions file number, which we did not verify. The CPSC database showed no recall on Oct 23, 2026. Do not leave any heater unattended on a flammable surface.