Let the material set the requirement
First obtain the exact manufacturer's process. Enter that temperature in the comparison tool. Then ask what evidence exists for the model at that setting with a loaded chamber. A display value, a rated maximum and a measurement near the center of a reel answer different questions.
Separate drying from other processes
Some equipment is marketed for both drying and annealing. Do not treat those words as interchangeable settings for a spool. Follow the relevant equipment and material instructions for the intended process, and do not use a product's broader marketing as a substitute for them.
Interpret a display in context
The E2 product information says its humidity display enters a protection state at elevated temperatures. That is a reason to read the display notes before using a low RH number as a stopping rule. A reassuring number can have a model-specific explanation unrelated to whether the spool has completed its required process.
Compare the full operating envelope
Record the permitted spool construction, room conditions, cycle limits and available support. Keep the budget for equipment separate from any measurement accessories you need to evaluate it. If a model merely touches the necessary maximum on paper, seek better evidence rather than assuming ample performance at the limit.
What the 85°C and 110°C limits change
The SUNLU S4 Pro’s documented range is 45–85°C; the E2’s is 35–110°C. If your exact material instructions call for 90°C, the S4 Pro does not meet that temperature requirement while the E2 passes this initial specification check. The E2 still needs separate checks for reel heat tolerance, fit, duration and the intended process. This is a capability comparison, not a measured performance ranking.
Why the E2 humidity number needs context
SUNLU documents a humidity-display protection state at 80°C and above. In that state a reading below 10% should not be used as evidence that the spool has completed drying. Follow the documented process rather than stopping solely on that display. The original product information is linked so you can check the current explanation and operating conditions.
Models to compare
Two controlled zones
SUNLU S4 Pro
Two temperature and time settings across four spools.
- Spools*
- 4
- Max temp
- 85°C
- Zones
- 2
Two zones offer more scheduling flexibility than one shared chamber.
Model details →
Higher-temperature chamber
SUNLU E2
A higher published ceiling for demanding material requirements.
- Spools*
- 2
- Max temp
- 110°C
- Zones
- 1
Spool temperature limits matter as much as the dryer's ceiling.
Model details →Source: SUNLU: E2 operation and humidity-display notes. Checked 13 September 2026. Manufacturer information; not a hands-on test.