SUNLU S1 Plus review: choose the material before the dryer

The SUNLU FilaDryer S1 Plus is a reasonable first dryer when you use one spool at a time and your material’s drying instructions fit its 35–55°C range. Its appeal is a small, uncomplicated piece of equipment that can improve a familiar printing routine. Its limitation is equally plain: buying a low-temperature dryer cheaply does not help if your next material needs a hotter cycle.

Choose the material before the machine. This model has successful PLA, TPU and PETG experiences behind it, but PETG feedback ranges from useful improvement to slow or disappointing results. A good outcome with one formulation does not settle the requirements of another.

The Plus version has a fan; the review history goes further back

SUNLU’s current S1 Plus documentation identifies a built-in circulation fan and humidity display. The Amazon history includes older S1 units, including accounts that explicitly describe a fanless box. Those older hardware descriptions should not be used to explain the current model.

The distinction is visible in more recent experience: buyers describe a working fan and note that earlier no-fan complaints did not match what arrived. Check the exact product name and supplied manual, especially when buying used stock. This review does not treat every historical S1 fault as a confirmed fault of today’s S1 Plus.

A sensible fit for one established material

The strongest case is a routine built around ordinary single-spool jobs. Improved PLA results, cleaner TPU printing and reduced stringing support using the box when moisture is a plausible cause of a changed print. A compact footprint also makes more sense for a small material collection than paying for empty extra slots.

There is no sound basis here for promising a universal six-hour rescue. Nor should a towel wrapped around the machine or a disconnected fan become part of the buying recommendation. Those changes appear in customer accounts, but they alter how the heater operates and are not a substitute for equipment with the required operating range.

Simple hardware, less obvious controls

Two physical buttons keep the front panel uncluttered. Some users quickly settle into a repeatable routine and appreciate starting the same cycle without a more elaborate interface. Others struggle to distinguish changing a value from switching between settings, especially with minimal instructions.

The practical question is how often you change the cycle. Repeating one setup can make the controls a minor inconvenience. Frequently moving between materials makes the learning curve more noticeable. Check the displayed time and temperature after adjustment rather than assuming the last button press did what you intended.

The current S1 Plus user guide specifies a 1–99-hour timer. The older S1 manual attached to the Amazon listing specifies 0–24 hours, which explains why the listing history contains different limits. Match the supplied model and manual before planning a long print; the longer timer does not raise the 55°C temperature ceiling.

Give the filament path as much space as the box

Successful print-through use is a real benefit: the spool can stay in the dryer instead of being moved after preparation. Recent accounts describe low-resistance rolling, and the current design is intended to dispense filament while operating.

But a small enclosure does not guarantee a small overall installation. The outlet angle may force a sharp bend toward the printer or feeder. One otherwise positive experience ends in a return because the route to an AMS Lite binds. Other accounts describe lid movement, difficult spool changes or a light box being pulled when the path resists.

A route that needs drilling, a forced bend or disabling a component to work is a reason to reconsider the installation. The purchase should solve a printing problem, not create a new mechanical one.

Judge drying by the job, not one humidity reading

The humidity display can help monitor chamber conditions, but it does not measure the water inside the filament. Our humidity-display guide explains what to check when the reading seems stuck. A complaint based only on a particular RH number does not establish ineffective drying, just as a lower number does not prove the whole spool is ready.

More relevant evidence includes changed print quality, persistent popping after treatment, or a material that requires a temperature beyond the machine’s range. Keep the material instructions and a repeatable print check central to the decision.

Fan-equipped units receive both quiet-operation praise and complaints about noise. Failure and unexpected-shutdown accounts also exist, alongside continued successful use. These justify checking operation during the return period; they do not establish a product-wide failure rate. Stop using a malfunctioning heater and contact support rather than repeatedly restarting it as a routine workaround.