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SUNLU S4 3D Printer Filament Dryer

SUNLU S4 3D Printer Filament Dryer

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

  • 4 spool capacity, 450×210×211mm internal chamber
  • 350W PTC heater, 70°C max temperature
  • 3 circulation fans, ±3°C uniformity
  • 458×218×312mm, 4.8kg, fits 1.75/2.85/3.0mm

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Summary

A four-spool active filament dryer with a 350W-class PTC heater, 70°C ceiling, auto humidity mode and eight PTFE filament outlets aimed at multi-printer and multi-color workflows. It dries fast and feeds up to four printers, but the preset temperatures can overheat filament, so set them manually.

Strengths

  • Auto humidity storage mode, and the chamber feeds up to four printers via PTFE outlets.
  • 12-month warranty with 7-day returns and 15-day exchanges from SUNLU direct.
  • Presets for PLA, ABS, PETG, TPU, PA and PC plus manual temperature and time controls.

Weaknesses

  • Rated power is inconsistent (300W to 350W across official documents) and unresolved.
  • The lid has no gasket, so it cannot double as a passive dry box when powered off.
  • A thermal camera measured about a 10°C spread across the chamber versus the claimed ±3°C.
  • The PETG preset fused four brand-new rolls into a single brick in one test.
  • No mainstream independent instrumented test exists; evidence is specialist sites plus manufacturer docs.
  • No user-serviceable parts catalog; the only documented failure path is an Er3 fan error.

Verified specifications

ModelSUNLU FilaDryer S4 (store code S4-FD).
Capacityup to 4 × 1 kg spools; internal chamber 450 × 210 × 211 mm.
HeaterPTC; official marketing says 350W, the spec sheet says 300W, SUNLU’s store and one retailer say 330W and a manual reprint says 350W.
Max temperature70°C.
Fans3 (dual side circulation fans plus bottom heating fan); claimed chamber uniformity ±3°C.
Heating speed25→50°C in ~30 minutes, 25→70°C in ~50 minutes.
Humidity controlauto start at 30–50% RH, stop below 25% RH.
Filament diameters1.75, 2.85 and 3.0 mm; 8 outlets (2 per side, 4 on top) with PTFE connectors.
Feedsup to 4 printers.
Controlstouchscreen with presets for PLA, ABS, PETG, TPU, PA, PC plus manual temperature and time modes.
Safetytriple protection (PTC thermistor, mechanical temperature switch, software monitoring).
Power inputAC 110–240V, 50/60 Hz.
Warranty12 months, listed in SUNLU’s warranty table, with 7-day return and 15-day exchange windows.
Dimensions458 × 218 × 312 mm; carton 516 × 278 × 350 mm; net 4.8 kg, gross 5.5 kg.
Materialspolycarbonate and ABS enclosure with a glass-fiber-reinforced polypropylene base.
Includeddrying box, power adapter, user manual, 2 × 100 cm PTFE tubes and 4 × 8 cm PTFE tubes.
Desiccantnot included; storage mode requires added desiccant and the outlets covered.
Full research notes and sources

Drying performance and measured results

The strongest hands-on evidence is specialist testing rather than a mainstream lab. A sponge test dried 2 ml of water bone-dry in 30 minutes and cut weight from 2.676g to 0.635g after an hour. A soaked-filament test showed PLA, PETG and TPU soaked to 85% RH printed poorly and improved sharply after 6 hours at 50°C, while nylon needed roughly 6 hours more at full heat to print nearly flawlessly. No Reddit threads specific to the S4 were located.

Noise and preset handling

Noise is not specified by the manufacturer, but it was measured at about 45 dB at half a meter and described as the second-loudest dryer in one roundup. The material presets are the real hazard: the PETG preset fused four new rolls in one test, and the repeated guidance is to set temperature manually, 5–10°C below the preset. Because the humidity trigger thresholds (start 30–50%, stop 25%) are fixed and not adjustable, owners in dry climates may rarely see the auto mode fire. A loose lid hinge on one early unit and tight stock PTFE tubes are the common QC complaints.

Running costs and upkeep

The recurring cost is electricity, with no consumable lock-in; desiccant for storage mode is a small recurring cost if you use it. SUNLU’s warranty policy explicitly lists S4 dryers at 12 months, with 7-calendar-day returns, 15-calendar-day exchanges and SUNLU paying shipping for confirmed quality issues; out-of-warranty customers can buy parts for self-repair or pay for service. The manual documents an “Er3” error meaning abnormal air-supply fan.

Is it worth it?

Makers101 priced it around $100 in July 2026 with a list price closer to $140, and SUNLU’s own store lists a $116.99 sale price against a $139.99 reference. At $100 it is strong value for multi-printer users, with noise and preset risk as the tradeoffs; $101–120 is good value; $121–140 is fair, where you compare modular PolyDryer units and gasket-equipped EIBOS models; above $140 it is weak, when a smaller quieter sub-50W S2 suits single-printer buyers and engineering-material users may outgrow the 70°C ceiling for the 85°C S4 Pro. The core value driver is 4-spool capacity plus 70°C at a low price, not the ±3°C uniformity claim, which one test contradicts.

Which model this is

This page covers the SUNLU FilaDryer S4, ASIN B0CQJMV71Z, a four-spool, white/black/grey dryer. It is the four-spool, 70°C, single-chamber model; do not merge it with the newer dual-chamber FilaDryer S4 Pro (45–85°C per zone, 380W, black only) or the older S1/S2/E2 dryers.

Sources

Manufacturer:

Independent reviews:

Owner reports:

Parts and stores:

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