SUNLU AMS Heater for Bambu Lab AMS: problems, parts and running costs

Checked: 2026-10-23

Summary

The SUNLU AMS Heater is a $99.99 powered replacement lid that adds active drying to a first-generation Bambu Lab AMS, drying while you print at 35-70°C. Owners report electrical arcing after about 100 hours, feeder heat damage during 50-60°C use, softened PLA and jams, fan resonance and humidity readouts that do not match a second meter. It has no scheduled consumable, so the only recurring cost is electricity, roughly $26.40 to $46.80 per year in the illustrative scenarios, and it is a good buy below about $90 delivered.

Common problems and fixes

Electrical arcing / fire risk — one r/BambuLab owner reported the mainboard of an approximately 100-hour unit sparking while running, after intermittent fan or cable resonance; no independent diagnosis or recall was found. Treat crackling, burning smell or visible sparks as an immediate stop-use condition. [10]
Possible AMS feeder or hub heat damage — one owner reported excess filament pulling after months of 50-60°C use for TPU; Bambu replaced the hub and motor and suspected heat, while SUNLU support reportedly advised staying below 40°C. That advice is not a published manufacturer-wide limit. [9]
Softened PLA and jams — owners reported PLA components deforming, filament kinking at the AMS funnel and loaded PLA snagging while another material dried; PETG replacements for printed accessories were suggested. [8]
Fan resonance — one owner with two units reported vibration and slow support response. [11]
Humidity readout mismatch — one unit read 20% while a separate device read 50%, and humidity rebounded near 50% about two hours after closing the lid in a humid apartment. [11][12]
Fit and shipping — one owner said the supplied Allen wrench was too large for the hinge screws; another reworked hinge clearance without achieving an expected seal. [8][17]
Manual vents — the manual says to slide the ventilation cover fully open during drying; owners say this extra step defeats set-and-forget automation. [2][11]
Shared temperature for all four spools — all four positions share one chamber, so a 65-70°C cycle for engineering filament can overheat PLA spools, printed adapters and AMS components. [2][5]

Parts and consumables

AMS desiccant, spool adapters, PTFE tubing, feed motors and rollers — belong to the existing AMS and are not included; no annual cost established. [2]

No scheduled consumable, filter or drying agent is prescribed.

Yearly running cost

No subscription or filter. Electricity only: rated 220 W, maximum 390 W, standby 0.6 W. Illustrative scenarios, not measurements: 3 hours of drying on 200 days at an assumed 220 W average = 132 kWh = $26.40 per year at an assumed $0.20 per kWh; at the 390 W maximum throughout = 234 kWh = $46.80; standby at 0.6 W for 18 hours a day = 3.942 kWh = $0.79. Unexpected AMS repairs, deformed accessories and desiccant have no defensible annual dollar amount. [2][3]

When it is a good buy

SUNLU US store listed the heater at $99.99 in October 2026, discounted from a displayed $119.99, with a historical reviewer citation of $119.99 regular / $109.99 sale in July 2025. Below $90 delivered is a good price for an owner of a compatible AMS who accepts the manual vents, shared temperature and emerging safety reports. Between $90 and $105 it is conditional. Above $110-120, consider a separate SUNLU FilaDryer S4 at about $116.99 or a more capable upgrade. If mixing PLA with engineering filament at different temperatures is routine, the EIBOS Tetras at about $199.99 offers four independently controlled compartments. The Bambu AMS 2 Pro at $359 is a full replacement with up to 65°C drying but does not dry while feeding. Avoid unattended use, and stop immediately on electrical crackling or arcing. [3][4][13][14][15][16]

Named alternatives:

SUNLU FilaDryer S4 — separate four-spool dryer at about $116.99 from the SUNLU store; better for drying away from AMS motors and internals. [13]
EIBOS Tetras — Gen 1 AMS compatible four-compartment heater at about $199.99 from the manufacturer, $189.99 at West3D; better for mixed materials needing independent zones. [14][15]
Bambu Lab AMS 2 Pro — complete replacement system with up to 65°C drying at $359; better for a new AMS, but it does not dry while feeding. [16]