Moisture in 3D printer filament is a common problem that can seriously impact print quality, causing issues like stringing, poor layer adhesion, and inconsistent extrusion. The Sunlu Filadryer S4 addresses these challenges head-on with its advanced fast-heating system, smart humidity control, and large capacity to dry up to four spools simultaneously.
Designed for both hobbyists and professionals, this filament dryer combines efficiency, safety, and versatility in one compact box. In this review, we’ll dive deep into its features, heating performance, and why it’s becoming a favorite among 3D printing enthusiasts looking for reliable, multi-spool drying solutions.
4 Spools, 1 Box – True Large-Capacity Drying in the Sunlu S4
One of the most remarkable features mentioned in every Sunlu Filadryer S4 review is its unprecedented drying capacity.
The Sunlu S4 filament dryer is designed to hold and dry up to four spools simultaneously, offering a compact yet high-capacity solution for multi-material or high-volume users.
Capacity Breakdown of the Sunlu S4 :
Feature | Specification |
Total Spool Capacity | 4 standard 1kg filament spools |
Internal Space | Expanded drying chamber for large reels |
Compatible Spool Sizes | 1kg (standard), mini rolls, multiple diameters |
Simultaneous Drying | Yes – all four spools dry evenly |
Usability | Ideal for farms, professionals, or multi-material prints |
Key Benefits of the 4 Spool Filament Dryer Design :
- Time-Saving: Dry four different filaments at once, reducing prep time between prints.
- Material Flexibility: Load PLA, ABS, PETG, and TPU together without the need to rotate them manually.
- Compact Solution: Instead of using multiple small dryers, the S4 offers central storage and drying in one tidy unit.
- Print Farm Friendly: Perfect for small production teams or print farms running multiple machines.
- Organized Workflow: Minimizes clutter and filament swaps by combining storage and drying in one box.
This Sunlu S4 review wouldn’t be complete without highlighting the breakthrough capacity. It’s not just a filament dryer — it’s a professional-grade 4 spool filament dryer built for scale, speed, and organization.
Before and After Drying with the Sunlu Filadryer S4: A Clear Difference
One of the key benefits highlighted in every Sunlu S4 review is how effectively it transforms wet filament into perfectly dry material ready for printing. Before drying, wet filament often causes multiple printing issues like poor layer adhesion and stringing. However, after using the S4 filament dryer, the filament dries thoroughly, resulting in a flawless printing surface and consistent print quality.
Wet Filament vs. Dried Filament with the 4 Spool Filament Dryer
Condition | Printing Outcome |
Wet Filament | Multiple printing problems |
Dried Filament | Smooth surface, perfect prints |
This dramatic improvement in filament quality is why the Sunlu Filadryer S4 consistently praises its drying performance, making it an essential tool for any serious 3D printing enthusiast or professional.
Heating Efficiency Breakdown – Sunlu Filadryer S4 Review
A major improvement highlighted in this Sunlu Filadryer S4 review is the advanced fast-heating system.
Compared to the earlier S2 model, the Sunlu S4 filament dryer significantly reduces the time needed to reach optimal drying temperatures, which is especially important for users handling moisture-sensitive filaments.
Heating Time Comparison - S4 Vs S2
| Model | Starting Temperature | Time to Reach 70°C | Heating Performance |
|---|---|---|---|
| Sunlu S4 | 25°C | ~55 minutes | Fast and efficient |
| Sunlu S2 | 25°C | ~80 minutes | Slower, less optimized |
Key Advantages of the S4's Heating System:
- Quick warm-up time helps reduce preparation delays.
- Stable and controlled internal temperatures for consistent drying.
- Even heat distribution across all spools, reducing the risk of uneven moisture removal.
- Increased efficiency in drying filaments like TPU, PETG, ABS, and Nylon.
- Designed for simultaneous multi-spool use, making it a practical 4 spool filament dryer for professionals and hobbyists.
The faster heat-up time and more effective thermal control clearly place the Sunlu S4 ahead of its predecessor. These enhancements make it a standout product in any detailed Sunlu S4 review, especially for users who value speed, reliability, and multi-spool drying capacity.
Smart Drying with Auto Humidity Control – Sunlu S4 Review
One standout feature in this Sunlu Filadryer S4 review is its intelligent auto humidity control system.
Designed to streamline the filament drying process, the Sunlu S4 filament dryer automatically starts or stops drying based on real-time humidity levels.
This feature ensures optimal drying without the need for constant monitoring, making it especially valuable for users handling multiple spools in the 4 spool filament dryer.
Auto Humidity Operation Table
Condition | Action Taken | Description |
RH ≥ 30%–50% | Auto Start Drying | Activates drying to prevent filament moisture. |
RH ≤ 25% | Auto Stop Drying | Halts drying to conserve energy and avoid overdrying. |
Key Benefits of the Auto Humidity Feature:
- Monitors and reacts to Relative Humidity (RH) levels in real-time.
- Reduces the risk of filament overdrying or cracking.
- Helps maintain filament quality during long printing sessions.
- Especially useful for moisture-sensitive materials like PETG, Nylon, and TPU.
- Fully integrated into Mode 2 for hands-free operation.
This smart drying capability places the Sunlu S4 ahead in terms of automation and efficiency. Whether you’re running batch prints or storing multiple filaments, the S4 filament dryer adapts dynamically.
Advanced Safety Features – Sunlu S4 Filament Dryer Review
A crucial highlight in any Sunlu Filadryer S4 review is the machine’s triple-layer safety system, ensuring secure and stable operation even during long drying cycles.
The S4 filament dryer isn’t just built for performance—it’s engineered with safety in mind, making it a reliable choice for professional and hobbyist 3D printing setups alike.
Triple Security System Overview
Security Level | Feature Name | Functionality Description |
Level 1 | Smart PTC | Provides stable heating while avoiding overheating risks. |
Level 2 | Temperature Switch | Automatically interrupts power if unsafe temperatures arise. |
Level 3 | Software Protection | Built-in system monitoring with alert mechanisms. |
Why Safety Matters in a 4 Spool Filament Dryer
- Continuous Monitoring: Real-time temperature tracking ensures filaments are not exposed to excessive heat.
- Unattended Operation: Safe for overnight or extended use without supervision.
- Hardware & Software Sync: Physical temperature control is supported by internal software protection, minimizing hardware failure risks.
- Multi-Spool Safety: Even with four spools running, each is equally protected by the integrated system.
This triple protection setup enhances the overall trustworthiness of the Sunlu S4, making it a standout model in any Sunlu S4 review. Whether you’re drying basic PLA or sensitive nylons, the machine offers a worry-free experience that’s rare in competing products.
Efficient Interior Design Boosts Performance in the Sunlu Filadryer S4
A core advantage often highlighted in every Sunlu S4 review is its intelligently engineered interior structure.
This design focuses on maximizing space while improving thermal efficiency for better drying results.
Feature | Benefit |
Maximized Interior Space | Allows for more filament capacity |
Minimized Heat Dissipation | Retains heat for consistent drying |
Elevated Electric-to-Thermal Conversion | Faster and energy-efficient filament drying |
Thanks to this optimized design, the S4 filament dryer delivers reliable performance, making it a leading choice in the category of 4 spool filament dryers.
360° Surround Heating and Powerful Airflow in the Sunlu Filadryer S4
One of the standout features praised in every Sunlu S4 review is its advanced heating and airflow system, designed to deliver uniform drying across all filaments. The S4 filament dryer uses a 330W PTC heater paired with three built-in circulation fans to maintain consistent temperature and ensure thorough drying.
| Feature | Specification | Benefit |
|---|---|---|
| Heating System | 330W PTC Heater | Efficient and stable heat generation |
| Airflow | 3 Circulation Fans | Balanced temperature distribution |
| Temperature Control | ±3℃ variance inside drying chamber | Ensures filament dries evenly from all sides |
Why Triple Fans Matter for the 4 Spool Filament Dryer:
- Provide 360° surround heating for consistent filament drying
- Maintain uniform temperature to prevent hotspots or under-dried spots
- Enhance electric-to-thermal conversion efficiency by maximizing heat retention
This thoughtful design makes the Sunlu Filadryer S4 a reliable and energy-efficient choice among 4 spool filament dryers.
Universal Compatibility Makes the Sunlu Filadryer S4 a Versatile Choice
Supporting up to 4 printers to dry or print simultaneously, the S4 filament dryer works flawlessly with nearly all filaments on the market.
Compatibility Feature | Details |
Number of Printers Supported | Up to 4 printers can dry or print at once |
Filament Compatibility | Compatible with 99.99% of 3D printer filaments |
Supported Filament Types:
- PLA / PLA+
- Silk
- PETG
- TPU
- Wood-filled
- PA (Nylon)
- ABS
- ASA
Supported Filament Diameters:
- 1.75mm
- 2.85mm
- 3.0mm
This wide-ranging support is a key reason why the Sunlu Filadryer S4 is highly regarded among users seeking a versatile and efficient 4 spool filament dryer.
Key Specifications :
Specification | Details |
Model | Sunlu Filadryer S4 |
Capacity | Up to 4 standard 1kg filament spools |
Heater Power | 350W PTC Heater |
Max Temperature | 70°C |
Temperature Range | 35°C – 70°C |
Timer Range | 0 – 99 hours |
Filament Diameter Support | 1.75mm, 2.85mm, 3.0mm |
Supported Filaments | PLA, PLA+, PLA Meta, PETG, ABS, TPU, PA, PC, Nylon, ASA, Wood-filled |
Fans | 3 Circulation Fans for 360° airflow |
Dimensions (External) | 460 x 220 x 310 mm (18.11″ x 8.66″ x 12.21″) |
Internal Dimensions | 450 x 175 x 207 mm |
Weight | 4 kg (8.8 lbs) |
Material | ABS + PC |
Color | Black |
Filament Exit Holes | 8 |
Pros and Cons of the Sunlu S4 :
Pros
Cons
- High Capacity: Dries up to four 1kg filament spools simultaneously, saving time and improving workflow.
- Fast Heating: Advanced 350W PTC heater reaches 70°C in about 55 minutes, 50% faster than earlier models.
- Smart Humidity Control: Automatically starts or stops drying based on real-time humidity levels to prevent overdrying.
- 360° Surround Heating: Three circulation fans ensure even temperature distribution and consistent drying.
- Wide Compatibility: Supports almost all filament types and diameters (1.75mm, 2.85mm, 3.0mm).
- Safety Features: Triple-layer safety system includes smart PTC heating, temperature switches, and software protection.
- Large Internal Space: Can accommodate large spools and various sizes, ideal for professional or multi-material setups.
- User-Friendly Controls: Adjustable temperature and timer settings for custom drying profiles.
- Compact Design: Consolidates drying and storage in one tidy box with eight filament exit holes for easy filament feeding.
- Size: Larger footprint may require more space on the workbench compared to single-spool dryers.
- Error Codes: Some users have reported occasional error codes (e.g., ER3) which may require support.
- Price: Slightly higher cost compared to simpler single-spool dryers, reflecting its advanced features and capacity.
- Weight: At 4 kg, it is heavier than smaller filament dryers, reducing portability.
Frequently Bought Together (Related Products) :
Conclusion :
The Sunlu Filadryer S4 stands out as a highly efficient and reliable filament dryer designed to meet the needs of both professional and hobbyist 3D printing users. With its rapid heating system, smart auto humidity control, and triple-layer safety features, the S4 ensures your filaments stay perfectly dry, preserving print quality and minimizing common issues caused by moisture.
Its large 4-spool capacity, combined with uniform 360° heating and powerful airflow, makes it an ideal choice for anyone managing multiple filaments or running a print farm.
While it offers advanced features and solid build quality, occasional users should be aware of minor reported issues like error codes, but overall customer feedback remains very positive. If you’re looking to improve your 3D printing results with consistent, professional-grade filament drying, the Sunlu Filadryer S4 is a compelling and worthwhile investment.
Looking for the best filament dryers of 2025? Check out our top picks here.
FAQ :
How loud is the Sunlu Filadryer S4?
Approximately 52 dB (measured from 1 foot away).
The Sunlu S4 features high-performance fans that ensure efficient airflow, but they produce a noticeable noise level of around 52 decibels. While not overly disruptive, it’s louder than most desktop devices and may not be ideal for noise-sensitive environments.
Is Sunlu filament good quality?
Yes, Sunlu filament is known for its consistent performance and excellent print results.
Here’s why users trust Sunlu filament:
Reliable Consistency: Precise diameter tolerances for smooth extrusion and high accuracy.
Excellent Print Quality: Minimal stringing, strong layer adhesion, and smooth surface finishes.
Wide Compatibility: Works well with various 3D printers and supports diverse materials like PLA, ABS, PETG, TPU, and wood filament.
Good Value for Money: Affordable pricing with performance comparable to premium brands.
Specialty Filaments: Options like PLA Meta (for low-temp printing) and high-speed filaments enhance usability.
While occasional reports of stringing or clogging exist, they’re typically resolved with proper tuning. Overall, Sunlu offers high-quality, cost-effective filaments for hobbyists and professionals.
Is Sunlu a Chinese company?
Yes, SUNLU is a China-based manufacturer.
Sunlu specializes in 3D printing products including:
3D filaments (PLA, PETG, TPU, etc.)
Filament dryers like the Sunlu S4
3D pens and accessories
The company is well-known internationally and serves the global 3D printing community.
What is the drying temperature range of the Sunlu Filadryer S4?
Adjustable from 35°C to 70°C
The Sunlu S4 allows you to fine-tune the drying temperature based on filament type via a front-facing touchscreen. Supported temperature range:
Minimum: 35°C
Maximum: 70°C
This range covers most standard and advanced filaments, including PLA, PETG, ABS, TPU, and Nylon.
What makes the Sunlu Filadryer S4 worth buying?
Professional-grade performance with smart automation and large capacity.
Key reasons why the S4 stands out:
4-Spool Drying Capacity: Simultaneously dries up to four 1kg filament spools—ideal for print farms or multi-material use.
Fast Heating System: Reaches 70°C in about 55 minutes, significantly faster than older models like the S2.
Smart Auto-Humidity Control: Automatically activates or halts drying based on internal RH levels for efficient moisture management.
360° Surround Heating: Three circulation fans and a 330W PTC heater ensure uniform drying and precise temperature control (±3°C variance).
Advanced Safety Features: Includes a 3-layer safety system—PTC protection, thermal switch, and software monitoring.
Efficient Internal Design: Enhanced airflow, minimized heat loss, and better thermal conversion for energy-efficient drying.
The S4 is not just a dryer—it’s a professional filament care station built for serious 3D printing needs.