The SUNLU S1 Plus and SUNLU S2 are both one-spool dryers, but the decision is simpler than their similar names make it look. The S1 Plus is the cheaper common-material upkeep pick with a circulating fan, live humidity display, and a 35-55 C range. The S2 is the stronger recovery pick because its listed ceiling reaches 70 C.
If your normal queue is PLA, PETG, or TPU and the goal is to keep one active spool in better condition while printing, the SUNLU S1 Plus on Amazon is the value-first lane. If you routinely recover wetter PETG or TPU, print ABS or ASA, or want more useful temperature headroom for nylon, the SUNLU S2 on Amazon is the safer buy.
Affiliate note: GoodPrints3D may earn a commission from qualifying Amazon purchases. Recommendations here are based on workflow fit, not on whichever model has the longest feature list.
SUNLU S1 Plus vs S2: the short answer
Buy the S1 Plus if...
- PLA, PETG, and TPU make up most of the queue.
- You want a fan-assisted print-from-box workflow without paying for heat you rarely use.
- A visible humidity trend and simple 35-55 C control are enough.
- The spool is usually exposed or mildly damp, not deeply saturated.
Buy the S2 if...
- You want up to 70 C instead of stopping at 55 C.
- Wet PETG, TPU, ABS, ASA, or nylon recovery is a recurring job.
- You prefer more temperature margin over the S1 Plus fan-and-display value story.
- The small price step is worth avoiding an early dryer upgrade.
Key differences at a glance
| Decision point | SUNLU S1 Plus | SUNLU S2 |
|---|---|---|
| Capacity | One spool | One spool |
| Listed temperature range | 35-55 C | Up to 70 C |
| Air movement | Built-in circulating fan | Choose it for the higher heat ceiling, not an assumed airflow advantage |
| Display emphasis | 2-inch screen for temperature, time, and relative humidity | Simple one-spool active-drying controls |
| Best material lane | PLA, PETG, TPU, and routine ABS upkeep | Common filaments plus more credible hotter recovery for ABS, ASA, and nylon |
| Best buyer | Beginner or budget owner maintaining one active spool | Buyer who wants more recovery headroom without moving to a larger dryer |
The real difference is 55 C versus 70 C
The S1 Plus tops out at 55 C. That is enough for a useful everyday lane: refreshing PLA, helping PETG or TPU that has been left exposed, and keeping a spool warm and enclosed through a long print. Its circulating fan and wrap-around heating design matter because even chamber conditions are more useful than simply warming one wall.
The S2 raises the listed ceiling to 70 C. That extra 15 C is the strongest reason to pay more. It gives wetter common filaments more recovery margin and makes the S2 the more credible choice when ABS, ASA, or nylon regularly enters the queue.
Do not turn that number into a universal material guarantee. Spool core temperature lags behind chamber air, different brands publish different drying guidance, and some engineering filaments still deserve a purpose-built hotter dryer. Temperature headroom helps; it does not erase drying time, spool geometry, or the material maker's instructions.
Why the S1 Plus circulating fan still matters
A lower maximum temperature does not make the S1 Plus pointless. Its built-in circulating fan addresses a common weakness in cheap dryer boxes: warm air sitting near the heater while the rest of the chamber changes more slowly. SUNLU also lists dual temperature probes and a 360-degree heating layout, giving this model a more deliberate common-material upkeep story than a passive warm box.
That makes the S1 Plus attractive when the problem is consistency rather than emergency recovery. If an open PETG spool gets progressively stringier during a humid week, or TPU softens and starts feeding less cleanly after sitting out, keeping the active roll enclosed and gently heated can be more valuable than buying the highest temperature number available.
Which dryer is better for PLA, PETG, TPU, ABS, ASA, and nylon?
PLA
S1 Plus is usually enough. PLA benefits from moisture control, but it rarely justifies choosing the hotter model by itself. Use the S2 only when it is also serving other materials or when the cost difference is small enough that future headroom matters.
PETG
S1 Plus fits upkeep; S2 fits stronger recovery. PETG often shows moisture as stringing, rough surfaces, popping, or inconsistent extrusion. A mildly affected spool can fit the S1 Plus workflow. A repeatedly wet spool or one that still behaves badly after a gentle cycle is a better match for the S2. The wet-filament diagnosis guide helps separate moisture from temperature, retraction, and nozzle problems first.
TPU
Both can make sense. Printing directly from an enclosed dryer is particularly useful for flexible filament. Choose S1 Plus for routine protection and S2 when the roll has already absorbed enough moisture that a stronger recovery cycle is the main job.
ABS and ASA
S2 is the better default. The S1 Plus can support moderate upkeep, but the S2's higher ceiling gives these materials more useful margin. Moisture is not the only concern here; chamber temperature and warp control still belong to the printer workflow.
Nylon
S2 wins, with a caveat. Nylon is demanding enough that 70 C is materially more useful than 55 C, but badly saturated nylon may still need more time or a higher-temperature system. Buy the S2 over the S1 Plus for nylon, but do not buy either solely because a generic chart promises instant recovery.
Can both dryers print while drying?
Yes. Both products occupy the one-spool print-through lane and support common external-filament paths. The S1 Plus listing covers 1.75, 2.85, and 3.00 mm filament routing; the S2 is also positioned for mainstream external-spool FDM use.
The box is only half of that workflow. Keep the filament outlet aligned with the printer, avoid tight PTFE bends, and confirm that the spool rolls freely. A dryer cannot fix feed resistance created by a sharp exit angle or a spool rubbing the lid.
How useful is the S1 Plus humidity display?
The S1 Plus screen shows temperature, remaining time, and relative humidity. That is useful for trend watching: humidity should generally fall as the chamber warms and moisture is carried away. It is not a direct moisture meter for the middle of the filament.
This distinction prevents false confidence. A low chamber reading can appear before the entire spool is conditioned, especially after a short cycle. Judge the result with print behavior as well: quieter extrusion, less stringing, cleaner surfaces, and more stable flow are better proof than one display number.
Choose by failure mode, not model name
- The spool prints well but gets worse while exposed: S1 Plus.
- PLA and PETG need routine one-spool upkeep: S1 Plus.
- Wet PETG or TPU keeps surviving mild cycles: S2.
- ABS, ASA, or nylon is a regular part of the queue: S2.
- You need to process two spools at once: skip both and compare dual-spool dryers.
- You want dry storage after the cycle: plan a sealed-storage handoff instead of leaving the spool in a vented dryer indefinitely.
The main filament drying guide explains how to set a repeatable cycle, while the filament storage guide covers what should happen after the spool is dry.
A better dry-then-store workflow for either SUNLU box
Start with the symptom instead of automatically running the longest, hottest cycle. Popping at the nozzle, sudden stringing, rough top surfaces, brittle behavior, or flow that changes as a spool sits out can support a moisture diagnosis. A mechanical feed problem, partial clog, or incorrect temperature can look similar, so verify the path before asking the dryer to solve everything.
For a known-damp spool, choose a material-appropriate temperature and give the center of the roll time to catch up with the chamber. The displayed air temperature changes sooner than the whole spool. After the cycle, run a small repeatable test model or the same troublesome part rather than changing retraction, flow, and nozzle temperature at the same time. Cleaner extrusion after drying is useful evidence; one lower humidity reading is not.
If the material prints correctly again, move it to sealed storage with maintained desiccant when it is not feeding the printer. Leaving a conditioned spool exposed until the next weekend simply restarts the moisture problem. The dryer should be the recovery and active-printing stage; a sealed box or bag should handle the idle stage.
This workflow also clarifies the buying decision. The S1 Plus is enough when gentle recovery plus controlled active use restores the spool. The S2 earns its extra heat when those common-material cycles repeatedly fall short or when the queue includes materials that genuinely benefit from the higher ceiling.
What the S1 Plus does better
- Lower-cost entry into active one-spool drying.
- Clear 35-55 C control for common-material upkeep.
- Built-in circulating fan, dual temperature probes, and wrap-around heating.
- One screen for temperature, remaining time, and chamber humidity.
- A sensible match for PLA, PETG, TPU, and ordinary print-while-drying use.
What the S2 does better
- Up to 70 C rather than stopping at 55 C.
- More credible recovery margin for wet PETG, TPU, ABS, ASA, and nylon.
- A broader material runway if the buyer expects the queue to expand.
- A larger existing GoodPrints support path through the SUNLU S2 review and SUNLU S2 specs guide.
When should you skip both?
Skip both single-spool models when capacity is the actual bottleneck. Two-color work, printer farms, and several open spools in rotation are better served by a dual- or four-spool system. Also step up when deep high-temperature engineering-filament recovery is the primary requirement rather than an occasional edge case.
If the S2 sounds close but you want another mainstream single-spool option, use the SUNLU S2 vs Creality Space Pi comparison. It is a cleaner next step than comparing every dryer on Amazon by wattage and screen design.
Bottom line
Buy the SUNLU S1 Plus for affordable fan-assisted upkeep of one PLA, PETG, or TPU spool. Buy the SUNLU S2 for the 70 C ceiling and the stronger recovery lane. The S1 Plus is not simply an older-looking S2, and the S2 is not automatically better for every beginner. One prioritizes common-material value and visible chamber feedback; the other prioritizes useful temperature headroom.
For most PLA-first beginners, the S1 Plus is enough. For mixed-material owners who expect ABS, ASA, nylon, or repeatedly wet PETG and TPU, the S2 is the purchase less likely to be outgrown.
Common questions
What is the maximum temperature of the SUNLU S1 Plus?
The listed adjustable range is 35-55 C.
How hot does the SUNLU S2 get?
The SUNLU S2 is positioned around drying temperatures up to 70 C.
Is the S1 Plus good enough for PETG?
Yes for routine upkeep and mildly damp PETG. Choose the S2 when the spool is repeatedly wet or a 55 C cycle does not restore consistent printing.
Which one is better for nylon?
The S2 is the better of the two because its higher ceiling provides more useful recovery margin. Very wet nylon can still justify a hotter purpose-built dryer.
Do these dryers replace sealed storage?
No. Dryers remove moisture; sealed storage and fresh desiccant slow its return. The most reliable workflow uses both at different stages.