SUNLU FilaDryer S4 Pro Review 2026: Does Dual-Zone Filament Drying Actually Work?

Between PLA, PETG, and the occasional PA (nylon) print, moisture-related stringing and layer adhesion problems used to eat up my weekends. I picked up the SUNLU FilaDryer S4 Pro from SUNLU to see whether its dual-zone drying actually solves that, and here's my honest take after running it through several print projects.

What You're Getting: FilaDryer S4 Pro Specs

I paid $139.99 from SUNLU. It fits 4 x 1kg filament spools, reaches a max temperature of 85°C, and runs two independent drying zones at once.

Key features

• Dual-zone independent temperature and time control — dry PLA/PETG in one chamber while conditioning PA/PC/PP in the other
• 85°C max temperature with upgraded heating and airflow circulation
• Built-in annealing mode for PA, PC, PP and engineering materials (up to 85°C annealing temp)
• Smart humidity management: set a target RH range of 30-50%, auto-starts and stops at 25% RH
• Compatible with PLA, PETG, TPU, ABS, ASA, and PA (Nylon)

Using It Across Real Print Projects

The dual-zone setup is the feature I actually use every week: I'll dry a fresh spool of PETG in one chamber while simultaneously conditioning a nylon spool in the other, instead of running two separate drying cycles back to back. Reaching 85°C didn't take long compared to my old single-zone dryer, and I noticed less stringing on PETG prints after a full drying cycle.

Annealing mode

I tested the annealing mode on a few PA prints that needed extra heat resistance, and it's a genuinely useful bonus feature rather than a marketing checkbox — dimensional stability held up under a stress test I wouldn't have tried on the untreated parts.

Pros and Cons

Pros

• Dual-zone control genuinely saves time when working with multiple materials
• Reaches 85°C quickly thanks to the upgraded airflow
• Automatic humidity-based start/stop takes the guesswork out of drying times
• Annealing mode adds real functional value for PA/PC/PP prints

Cons

• At 4 x 1kg capacity, it can fill up fast if you run larger multi-color projects
• 85°C max means it's not suited for materials that need higher-temperature drying

Final Verdict

For anyone printing with more than one filament type regularly, the dual-zone control alone justifies the SUNLU FilaDryer S4 Pro over a basic single-zone dryer. Combined with code Y2OSYGCK9B at SUNLU, it's an easy recommendation for a serious home 3D printing setup.

You can check current pricing directly at SUNLU.