Which motor is malfunctioning
Are there pellets in the hopper but none in the burn pot, or is dosing running unevenly, the fault is typically in the gear motor or the auger it drives. The gear motor runs at short intervals to dose the pellets, so it remains stationary for much of the time, even when it is working. If it hums without the auger turning, or is completely dead when the stove calls for pellets, it is worn out, or the auger is stuck.
If the stove gives a flue gas or draft alarm, smoke enters the room, or the glass becomes sooty with a lazy yellow flame, it is the flue gas extractor that needs to be checked. It creates the negative pressure in the combustion chamber, and without it the pellets receive too little air and the flue gas cannot find its way out. A flue gas extractor that makes noise or vibrates is often worn in the bearings, but it may also simply be soiled with ash.
If the stove burns normally but the heat remains in the stove, it is the fan that is failing. Without air circulation, the stove becomes too hot and may switch off on the overheat protection. The room air fan is available both as a long tangential fan and as a round centrifugal fan, and noise, rumbling or uneven operation are typical signs of wear.
Where the motors are located in the stove
The location helps confirm which motor is involved. The gear motor is located on the auger between the pellet hopper and the burn pot, the flue gas extractor is located at the rear of the stove by the flue outlet, and the fan is typically located at the bottom, where it blows air past the combustion chamber and out into the room.
The parts are known by several names. Flue gas extractor, flue gas extractor motor and flue fan refer to the same part, and the same applies to fan, blower and centrifugal fan, so search by brand and model rather than by the name alone.
When the fault is in the accessories
A new flue gas extractor or fan typically costs 800 to 2,500 kr., while the fault is sometimes in a part costing 100 to 300 kr. If a flue gas extractor or centrifugal fan hums without reaching speed, the capacitor may be weak. If the flue gas extractor runs while the stove still gives an alarm, the encoder that measures the revolutions may be defective. If smoke or odour comes from the rear of the stove, the gasket between the flue gas extractor motor and housing is an obvious place to start. It can therefore be worthwhile to rule out the accessories before replacing the motor.
