SUNLU FilaDryer S4 White

SUNLU FilaDryer S4 White

By SUNLU · Filament Dryers · 3D Printing · More from SUNLU

  • Capacity: 4 spools of 1 kg
  • Internal size 450 x 210 x 211 mm
  • Heater: 300 W PTC, rated power 320 W
  • Maximum temperature: 70 C
  • Chamber temperature balance within 3 C (manufacturer)

Lowest price seen
~$116.99 (approx.)
from $116.99 at Amazon

Prices are snapshots. Check the current price with the store.

Summary

A 4-spool filament dryer for multi-material or multi-printer workshops, with humidity-based auto start/stop and feed-through to up to four printers. Check the noise before you buy: a Reddit thread measures 53–62 dB and calls it “VERY LOUD”, contradicting SUNLU’s “whisper-quiet” marketing.

Strengths

  • Holds four 1 kg spools and feeds up to 8 printers through PTFE tubes, so one unit covers a multi-printer workshop.
  • Humidity setpoint with auto start/stop means you can leave it unattended without over-drying.
  • Built-in presets for PLA, ABS, PETG, TPU, PA and PC remove guesswork.
  • GearDiary went from a failed wet-PETG benchy to a successful print after overnight drying.
  • Clever Creations recommends it for consistent drying results, build quality and ease of use.
  • 3DWithUs measured humidity dropping from 45 % to 26 % in about 4 hours.

Weaknesses

  • Fan noise is the main caution: a Reddit PSA thread measures 53 dB closed, 59 dB open and 62 dB while drying, louder than a Prusa XL printer.
  • The ER3 error (slow temperature cooldown) is a known issue; the community fix is 5 mm standoffs under the bottom panel.
  • No rubber feet — metal bar legs transfer vibration to the surface below.
  • Stiff roller bearings have caused TPU feeding failures, though SUNLU sent replacements to at least one user.
  • PCL and other low-temperature filaments can melt: FirstQuadcopter observed dripping after 20 minutes.
  • Heater wattage is listed inconsistently across sources (300 / 320 / 330 / 350 W) with no explanation.

Verified specifications

ModelS4-FD, White variant (also available in Black and Grey).
Internal capacity450 × 210 × 211 mm per the product page; 450 × 175 × 207 mm per the manual.
External dimensions458 × 218 × 312 mm (product page); 460 × 220 × 310 mm (manual).
Weight4.8 kg net (product page), 4 kg net (manual); 5.5 kg gross.
HeaterPTC element; wattage listed as 300 W (official page, wiki, manual), 320 W (store), 330 W (FirstQuadcopter, Conrad, Manuals+), or 350 W (SUNLU blog).
Maximum temperature70 °C; setting range 35–70 °C.
Chamber uniformity±3 °C claimed by SUNLU, not independently measured.
Humidity controlsetpoint 30–50 % RH; drying stops at 25 % RH.
Filament diameters1.75 mm, 2.85 mm, 3.0 mm.
Filament outlets8, with PTFE tube connectors.
PresetsPLA, ABS, PETG, TPU, PA, PC.
Displaytouchscreen with 1-second response (per Filament2Print).
Capacityup to four 1 kg spools.
Operating modesMO1 (time control) and MO2 (humidity control).
PowerAC 110–240 V, 50/60 Hz; standby 0.25 W; max current 3.1 A.
Drying timeup to 99 hours; 3–6 hours recommended for most materials.
SafetyPTC thermistor, mechanical temperature switch, software monitoring with real-time alerts.
In the boxdryer, power adapter, manual, 2× 100 cm PTFE tubes, 4× 8 cm PTFE tubes, 8 rubber plugs, 8 metal clasps.
Full research notes and sources

Noise and vibration

The S4’s fan system is its most contested feature. SUNLU’s blog claims “whisper-quiet operation” and cites user feedback about office suitability, but a Reddit PSA thread tells a different story: 53 dB with the lid closed, 59 dB open and 62 dB during active drying, which the author calls “VERY LOUD” and louder than a Prusa XL printer. The discrepancy may depend on fan speed setting and measurement distance, but the gap between marketing and owner measurement is large enough to check before buying if noise matters in your space. Creative fixes include replacing the 20 mm-thick fans with thinner Noctua models.

Vibration transfer is a related complaint. The unit has no rubber feet and rests on stainless steel leg bars, which carry fan vibrations into the surface below. Clever Creations recommended SUNLU address this. A Prusa forum user also noted the box is “completely closed” with no active moisture removal path other than the filament holes.

Drying performance and controls

The S4 heats from 25 °C to 70 °C in about 50 minutes with the 330 W PTC heater (FirstQuadcopter). 3DWithUs measured humidity falling from 45 % to 26 % in roughly 4 hours and noted a loose top-lid hinge that needed a manual push. A Reddit user reports humidity dropping to 14 % during TPU drying. The touchscreen responds in about 1 second and displays temperature, time, humidity, material type and countdown (Filament2Print).

The humidity setpoint (30–50 % RH) and stop threshold (25 %) are manufacturer values, not independently measured. SUNLU claims ±3 °C chamber uniformity, but no independent instrumented test was found and a Prusa forum user noted the “hot spot” problem common to consumer dryers.

ER3 error and repairs

The ER3 error appears when temperature cooldown is too slow and is interpreted as a fan failure. The community fix is to lift the bottom panel with 5 mm standoffs to allow passive airflow; this is published as a model on MakerWorld. The trade-off is that the modification reduces the dryer’s ability to hold humidity when powered off.

The manual lists three error codes: ER1 (abnormal temperature detection — check sensor connection), ER2 (abnormal PTC heating fan — check if fan is stuck) and ER3 (abnormal air supply fan — check if fan is stuck). SUNLU has a troubleshooting page for these codes.

Stiff roller bearings have been reported on the Bambu Lab forum as a cause of TPU feeding failures. Rollers can be swapped between positions, and SUNLU sent replacements to at least one user. No comprehensive parts catalog (heater, fans, control board) is listed on the public product page. Warranty is 1 year per the store listing, with exclusions for non-original power supplies or improper use.

Running costs and value

Electricity is the main recurring cost: 300–350 W during operation and 0.25 W standby. Replacement PTFE tubes and desiccant for the desiccant tank are the only other consumables. The manual recommends using desiccant to prevent re-wetting.

3DWithUs listed the S4 at $129.99 in September 2023. The SUNLU store lists it at $116.99 (regular $139.99 crossed out) on the Spanish storefront, and the US store shows the same pricing structure. A reseller snapshot from sunluessentials.shop also showed $116.99. The S4 Pro (dual-chamber, 85 °C) is $139.99 at the SUNLU store. At ≤ $130 the S4 is a strong choice for multi-spool drying with humidity control and feed-through; above $160, dual-chamber dryers may offer more versatility unless the 4-spool workflow is essential.

Which model this is

This page covers the SUNLU FilaDryer S4 in White, model S4-FD. The White variant uses the same chassis, heater, controls and capacity as Black and Grey; only the exterior color differs. Do not merge it with the S4 Pro (dual-chamber, 380 W, 45–85 °C) or the smaller S2 (single-spool). The Amazon listing for the White variant is ASIN B0CTH28YMH.

Sources

Manufacturer:

Independent reviews:

Owner reports:

Manuals:

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