Question 1

Does the S2 truly heat 360° around the spool, or is it only bottom-heated?**

Accepted Answer

Good question—many TikTok and Reddit users have asked the same. The S2 uses 360° all-round heating, meaning the heating element wraps around the sides and bottom for more even warmth than the older S1 model. That said, the top of a full spool can sometimes be a few degrees cooler, especially for taller or 2kg reels. For most PLA and PETG prints, the performance is excellent, but if you frequently dry nylon or polycarbonate, we’d recommend rotating the spool halfway through the cycle for best results.

Question 2

Will this fit larger or cardboard spools, like Polymaker or 2kg reels?**

Accepted Answer

The S2 is designed for standard 1kg spools up to 200mm in diameter. Cardboard spools or 2kg reels with a wider profile may be a tight squeeze and could require gentle pressure to close the lid. Some users on YouTube have trimmed the center spindle for a looser fit, but out of the box, we suggest double-checking your spool dimensions. For a more spacious option, the Sunlu S4 dual-spool dryer is a popular alternative.

Question 3

How loud is the fan during operation? Is it okay for a bedroom or office?**

Accepted Answer

The fan is notably present—think of a small desktop PC running under moderate load. At around 45–50 dB, it won’t drown out a conversation, but it might be distracting for light sleepers or quiet room recordings. Many hobbyists run it in a garage or workshop without issue. If noise is a top concern, we recommend searching “Sunlu S2 noise” on Reddit for mods (like a silicone pad) that some users have used to dampen the vibration.

Question 4

Can I print directly from the dryer? Does it work with a filament sensor?**

Accepted Answer

Yes, the S2 has a small passthrough port on the side and a PTFE tube fitting, so you can feed filament directly into your printer while drying. It works with most common filament sensors, though some users noted that the port angle may be tight for printers with top-mounted extruders. A simple fix is adding a short extension tube. We recommend testing the path with a dummy spool first to avoid snags mid-print.

Question 5

What’s the return and refund policy if it doesn’t work for my setup?**

Accepted Answer

Sunlu offers a 30-day hassle-free return from the delivery date, as long as the product is in original condition. A few Amazon buyers have reported that getting a response from support can take 24–48 hours, but replacements for defective units are generally processed quickly. For compatibility questions, our customer support team is happy to help before you buy—just send us your spool make and model, and we’ll confirm fitment.

Sunlu Official Improved Filament Dry Box S2, Filamento Dry Box with 360° All-Round Heating, Filament Storage Box for 3D Printers Keeps Filament Efficiently Dry, Filament Dryer, Black

Analysis Details

Was this analysis helpful?

What are you buying this for?

Have questions about this product? Ask the community.