When a mosquito coil heater comes back from the field, the heating element is rarely the reason. On most units we open, the tube still draws its 4-6 W and still reaches temperature. What has changed is the contact between coil and bracket. A dulled surface, a spring that has lost its tension, a coil sitting a millimetre off flat. The active ingredient stops vaporising long before the heater stops heating.
That is why we build the bracket as part of the heating assembly rather than as mounting hardware bolted on at the end. What follows is what actually happens to these units in humid rooms, and which numbers on the specification matter when you source one for OEM production.
The mosquito coil heating tube with bracket runs a PTC element at 145°C ±5°C on the surface, from a 100-240V AC supply, at 4-6 W. The narrow band matters more than the absolute figure. Push the surface much higher and the coil scorches at the contact point: the binder chars, the repellent burns off within a few hours, and the end user reports that the heater smells. Run it cooler and the spiral glows at the outer edge while never releasing enough vapour along its full length.
PTC ceramic makes that band easy to hold. Element resistance climbs steeply as the disc warms, so the heater settles at its designed Curie point instead of running away when a coil sits slightly off-centre or the room gets warmer in the afternoon. No bimetal cycling, and no thermostat to weld shut.
Mosquito season and rainy season overlap across much of Southeast Asia, southern China and coastal India. Those rooms sit at 80-90% relative humidity for weeks. A zinc-plated steel bracket develops white rust right at the spring contact, resistance between coil and bracket climbs, and the heater keeps glowing while the coil quietly stops working. Customers tell us they replaced the whole unit when a bracket would have fixed it.
Ours is aluminium with a powder-coated finish, tested to 96 hours of salt spray without corrosion. Aluminium also keeps the thermal path short, so the coil rests on a surface close to element temperature instead of 20-30°C below it.
Contact pressure is the other half of the job. The spring-loaded tension holds spiral coils, square mats and liquid pads without crushing them, because a crushed coil changes its own burn profile. That spring has to survive being compressed and released every night for a whole season. One that relaxes after a few hundred cycles has failed in the field even if the element still tests good.
Most enquiries we handle are for 220-240V markets, though the same tube goes into 110-120V assemblies. The element is built for the full 100-240V AC band, and the cord set, plug and fuse are matched to the destination market rather than to the tube alone.
Each unit leaves the line after a 1500V AC dielectric test held for 60 seconds, with the crimped and soldered joints inspected before assembly closes. Earlier in the process, samples run 72 hours continuous at 10% over nominal voltage, which is where weak PTC discs and thin thermal interfaces show themselves. A thermal fuse sits in the circuit as the last line of defence if someone drapes a towel over the unit.
The footprint is 85 x 45 x 25 mm including the bracket, which suits the flat base of most coil stands and leaves room for a small rocker switch. If your housing is tighter than that, the bracket geometry is the first part we change, since the tube and PTC stack are common across the range.
Three decisions settle most of the specification: the surface temperature band your coil formulation needs, the bracket material for the climate you ship into, and the coil format the unit must hold. Give us the coil dimensions plus the destination market's voltage and we will confirm tube length, spring tension and coating before quoting. Standard brackets ship from our Ningbo plant; custom geometry goes through the same sample process.
Comparing against your current supplier? The mosquito coil heating tube with bracket page carries the full specification, and the wider tubular and cartridge heaters range covers the rest of the appliance line. Sample requests and OEM drawings go through the inquiry form on either page.
