SUNLU FilaDryer S2 vs Polymaker PolyDryer

Who this comparison is for

This page is for anyone choosing between these two specific products: the SUNLU FilaDryer S2 in Black, and the Polymaker PolyDryer kit (SKU PX01002_A), which is one Dry Dock plus one PolyDryer Box with a US plug. Polymaker also sells the box and the dock separately, and a larger Box XL for 3 kg spools, but this page covers the kit. If you're still deciding whether you need an active dryer or just a sealed box, start with our filament dryer vs dry box guide. For the S2 against other SUNLU dryers, see our SUNLU FilaDryer E2 vs S2 and SUNLU FilaDryer SP2 vs S2 comparisons, or our eSUN eBOX Lite vs SUNLU FilaDryer S2 comparison. For the PolyDryer Box used as storage, see our PolyDryer Box vs Creality storage box comparison. For more dryers, including ones that run hotter than 70 °C, see the filament dryer shortlist.

How we compared them

This is a research-based comparison. Every figure below comes from the makers' own product pages, wikis, manuals, and blog, listed in the sources, plus Bambu Lab's and Prusa's published drying tables for the materials. We haven't tested either dryer, so nothing here is a measured result of ours. Where a maker describes its own product, such as "the best sealing performance on the market," we label it as the maker's claim.

The two makers describe heat differently. SUNLU gives a set temperature range. Polymaker gives power levels and a temperature range it says varies around the spool. Neither publishes a measured chamber temperature under the same conditions, so we list each maker's figure rather than treat them as a head-to-head.

Side-by-side specs

Temperature: a set point vs power levels

This is the clearest difference in how you use them. The S2 lets you pick a temperature between 35 and 70 °C. SUNLU says its screen has one-touch presets for different filament types, and it shows temperature, time, humidity, filament type, and a countdown.

The PolyDryer doesn't take a temperature at all. You pick one of three power levels and a drying time. Polymaker's FAQ explains why. Its 360° drying system "creates a temperature distribution" inside the box, so "a single temperature can't represent the true situation as it varies around the spool," and the room temperature, the spool, and the material all affect it. It gives one figure, "The highest range though is 68-73°C."

So both reach about 70 °C at most, but only SUNLU publishes a set point. If your filament maker gives a precise drying temperature, the S2 lets you dial it in. With the PolyDryer you follow Polymaker's power-level table instead.

Spool fit and capacity

Both hold one spool, and their maximum sizes are close.

• SUNLU FilaDryer S2. SUNLU's wiki gives a maximum of φ210 × 85 mm, and its comparison blog says it holds "one standard 1 kg spool."
• Polymaker PolyDryer. The manual gives a maximum of 205 mm diameter × 78 mm, filament with spool, and the product page says the box "Supports up to 1kg." Polymaker sells a separate Box XL for 3 kg spools, which needs a separately sold adapter to sit on the dock.

Bambu Lab lists its reusable spool at 200 mm across and 67 mm high, which is inside both limits. The S2's extra 7 mm of width matters only for spools wider than 78 mm. Spool sizes vary by brand, so measure yours. "Fits a 1 kg spool" doesn't mean it fits every 1 kg spool.

Feeding the printer and keeping filament dry

SUNLU's store page says the S2 "Allows you to print while drying," and that its feed-out coil "allows the filament to continue to dry in the dryer as it's being fed to the printer."

The PolyDryer works in two steps. Polymaker's manual has you feed the filament through the box's outlet, remove the airlocks, set the box on the dock, and dry. When drying is done, you lift the box off the dock and fit the airlocks back "tightly to ensure the best seal." The box then stays sealed while filament feeds out, with the hygrometer and desiccant inside. Polymaker calls this "the best sealing performance on the market." That's its claim, with no test figures on the product page. Its wiki adds that one dock can serve any number of boxes, so you can keep several spools sealed and dry them in turn.

The PolyDryer also has a Continuous Mode that runs until you stop it. The manual says, "DO NOT leave the dryer unattended when switched to Continuous Mode," so it isn't a set-and-forget heater for long unattended prints.

Which materials each maker says it can dry

Both makers list engineering materials, but their top temperatures are below what Bambu Lab and Prusa give for several of them.

• SUNLU FilaDryer S2. SUNLU's product page says it "Supports heating up to 70°C, suitable for specialty filaments such as PA and PC," and the store page lists PLA, PLA+, PETG, TPU, ABS, PA, and PC. SUNLU's own comparison blog is more cautious. It lists "Not suitable for high-temp engineering filaments" as a con of the S2, and points readers who print nylon and PC to its 110 °C E2 instead.
• Polymaker PolyDryer. The manual lists PLA, PVB, PETG, ABS, ASA, TPU, PA, PC, PVA, PolySupport, and PolySupport for PA12, with recommended drying times of 6 hours for PLA, PolySupport, PETG, ABS, ASA, and PC, 12 hours for TPU and PolySupport for PA12, 18 hours for PVB and PA, and 24 hours for PVA. It says those times are based on samples left at 25 °C and 70% RH for five days.

Here is how the filament makers' own drying temperatures compare with a dryer that tops out at about 70 °C.

Bambu's filament guide gives single figures of 80 °C for ABS, ASA, and PC, and 80 °C for 8–12 hours for PA. The same guide gives 55 °C for PLA and 70 °C for PETG, so by that table PETG also sits at the limit of both dryers. Bambu also warns that PA-based filaments left in open air for about three months become "very difficult to dry" even at 80–90 °C. So either dryer can run longer at its top heat on these materials, but neither reaches the temperature these makers give. Follow the drying guidance for your exact spool. If it calls for more than 70 °C, use a dryer documented to reach it.

Spool temperature limits

A dryer's top heat is only useful if the spool can take it.

• Bambu Lab's reusable spool guide rates its low-temperature spool, used for PLA and PETG, at 70 °C or below, and its high-temperature spool at 90 °C or below. Bambu warns that "Some third-party spools may not be heat-resistant enough and could deform during drying."
• Prusa says the black Prusament spool it introduced from October 2025 resists drying temperatures as high as 90 °C, but that older black Prusament spools are only safe to about 45 °C unless you add a screw to hold them together.

At about 70 °C, both dryers sit right at the limit of Bambu's low-temperature spool. Neither dryer maker publishes a spool temperature rating, and Polymaker doesn't publish one for its own cardboard spools, so check your spool before you run either dryer at full heat.

Power and footprint

The S2 lists a 48 W maximum working power and the PolyDryer 68 W. Both run from a 24 V DC adapter. The S2 is wide and low, 265 × 274 × 118 mm. The PolyDryer is narrow and tall, 235 × 120 × 290 mm with the box on the dock, which takes less desk width but needs more height. Neither maker publishes drying-time or energy-use figures we could compare.

What each maker says it's for

• SUNLU FilaDryer S2. SUNLU calls it "designed as a drying and storage box for 3D printer filaments," and its comparison blog positions it for "Beginners, students, or anyone with a single printer and limited space," mainly printing PLA and PETG. The store page claims it runs below 10 dB.
• Polymaker PolyDryer. Polymaker describes it as "When drying meets storage," with one dock serving as many boxes as you need, sealed boxes you don't have to open to print, and "Continuous filament drying as needed during storage."

SUNLU

SUNLU FilaDryer S2 (Black, single-spool dryer)

Best for

Drying and feeding one standard 1 kg spool of PLA, PETG, or TPU at a time.

Skip this if

You need to dry several spools at once or need temperatures above 70 °C.

Specs, strengths, and limitations

Capacity

One spool up to 210 mm diameter × 85 mm wide (SUNLU wiki: max capacity φ210×85(H) mm; SUNLU comparison: one standard 1 kg spool)

Outer size

265 × 274 × 118 mm

Part rated to

70 °C (your printer's own hotend limit may be lower)

Maker notes

Temperature setting range 35–70 °C (SUNLU wiki). Max working power 48 W (SUNLU product page and wiki). SUNLU describes dual upper and lower heating plates with a bottom fan ('360° Enclosed Heating') and a real-time humidity readout. Filament diameters 1.75 / 2.85 / 3.00 mm (SUNLU store page); SUNLU wiki lists 1.75 / 2.85 / 3.01 mm. SUNLU dimensions are 265(L) × 274(W) × 118(H) mm; recorded here as width = L, depth = W. SUNLU pages give different screen sizes (4.6-inch on sunlu.com, other figures on the store page), so screen size is not recorded. Timer range is not stated on SUNLU's product pages.

Strengths

• Manufacturer states a 35–70 °C setting range with heating plates above and below the spool and a bottom fan.
• Manufacturer states filament can keep drying while it feeds to the printer.
• Manufacturer lists a low 48 W maximum working power.

Limitations

• Holds a single spool, and SUNLU lists a maximum spool size of 210 mm diameter × 85 mm width, so wide or 2–3 kg spools will not fit.
• 70 °C maximum is below the drying temperature some engineering filaments call for; check the filament maker's drying guidance.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Polymaker

Polymaker PolyDryer (Dryer Dock + Storage Box kit, US plug (PX01002_A))

Best for

Readers who want to dry a spool and keep it sealed in the same box, then add more boxes over time.

Skip this if

Your spools are wider than 78 mm or you need precise temperature control.

Specs, strengths, and limitations

Capacity

One spool up to 1 kg; maximum 205 mm diameter × 78 mm (filament with spool), per the PolyDryer user manual

Outer size

235 × 120 × 290 mm

Maker notes

Polymaker SKU PX01002_A = PolyDryer (Dryer Dock + Storage Box), US plug; matches the Amazon model number. Manual: product size 235(L) × 120(W) × 290(H) mm; storage box alone 235 × 120 × 235 mm. Manual: power adapter input AC 100–240 V, output DC 24 V, 68 W maximum working power. The wiki says the Dock uses a PTC heater and draws 68 W. Uses 3 preset power levels rather than a set temperature. Polymaker FAQ: temperature varies around the spool, and 'The highest range though is 68-73°C.' Box includes a hygrometer and colour-changing desiccant (orange when dry, dark green when wet); filament feeds out through airlocks without opening the box. Manual: working environment 20–35 °C; filament diameters 1.75 / 2.85 / 3.00 mm. Polymaker FAQ: the hygrometer's minimum readout is 10%. Manual: timer max 24 hours in Regular Mode; Continuous Mode runs until stopped, and the manual says: 'DO NOT leave the dryer unattended when switched to Continuous Mode.'

Strengths

• Manufacturer states one Dry Dock can serve any number of separately sold PolyDryer Boxes, which stay sealed after drying.
• Manual has you feed the filament through the box's outlet plug and refit the airlocks tightly after drying, so you can print without breaking the seal.
• Manual lists a 68 W maximum working power.

Limitations

• Polymaker's manual lists a maximum spool size of 205 mm diameter × 78 mm, so wider spools will not fit the standard box.
• No exact temperature setting: three power levels, with Polymaker stating the highest range is about 68–73 °C.
• Holds one spool up to 1 kg; 3 kg spools need the separate Box XL and an adapter.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Verdict: which should you buy?

Choose the SUNLU FilaDryer S2 if…

• You want to set an exact drying temperature between 35 and 70 °C.
• You want to dry one spool beside the printer and feed from it while it heats.
• Your spools are up to 85 mm wide, slightly wider than the PolyDryer box takes.

Choose the Polymaker PolyDryer if…

• You want to dry a spool and then keep it sealed in the same box, with a hygrometer and desiccant inside.
• You plan to add more boxes over time and dry them in turn on one dock.
• You're happy to work from power levels and Polymaker's drying table rather than a set temperature.

Safety and limits

How this page was checked

Every specification, temperature, and drying figure above comes from the manufacturer documents in the sources section, retrieved on 2026-10-09. We haven't used either dryer for this page, so nothing here is a measured result of ours. SUNLU's pages disagree with each other in places. The store page gives several screen sizes, while the product page and wiki give 4.6 inches, and the product page says the S2 suits PA and PC while SUNLU's blog says it isn't suited to high-temperature engineering filaments, so we've reported both. SUNLU's wiki lists a 3.01 mm filament diameter, which we've taken as the 3.00 mm its store page gives. SUNLU's linked user manual is a scanned image we couldn't extract, so we haven't used it. Polymaker's manual groups materials into power levels in merged table cells that don't extract cleanly, so we've listed its drying times but not which level each material uses. Read more in our editorial standards and affiliate disclosure.

Dryers & dry boxes: what to check before you buy ↗