Type WQD: Wood and solid fuel stove damper bulb and capillary thermostat


This thermostat is an automatic control of wood, pellets, coal or anthracite fired solid fuel appliances like room heaters, boilers, stoves, central heating units.

Its modulating action provides economy in fuel consumption.

Main features

Operation principle: It controls the combustion by throttling the primary air intake to the fire. A flat damper plate at the end of the control arm is moved relative to the air intake port of the appliance in response to variations of temperature at the bulb.

It is actuated by the expansion of liquid in the bulb, through capillary tubing to a diaphragm located in the body.

Body: Zinc plated steel

Shaft: Dia. 6mm, with 4.8mm flat, with 270° angular rotation.

Fixing:  By means of the backside bracket, for dia 4mm screws, distance 42 to 48mm (Front mounting by 2 screws M4, 28mm distance available on request)

Temperature Ranges:

-Room Air Control 4/40°C (40/105°F). Damper displacement between 4 and 40°C (40/105°F), with a 170mm length arm: 12.5mm

-Hot water 30/90°C (85/195°F)). Damper displacement between 30 and 90°C (85/195°F), with a 170mm length arm: 9.5mm

-Flue temperature 50/300°C (120/570°F). Damper displacement between 50 and 300°C (120/570°F), with a 170mm length arm: 9.5mm

Other temperature ranges and displacement available on request (MOQ apply)

Damper plates

Damper plates are available in circular form in dia. 80mm and dia.  120mm. (Rectangular forms on request).They are spring mounted to permit self-alignment of the plate in the closed position.

Damper plate position can be adjusted from 150 to 170mm on the arm.

Damper plates are fitted with a temperature resistant silicone gasket.  Special arm length and damper plates may be made on request to suit application (MOQ apply).

Sensor dimensions:

Bulb and capillary are made of stainless steel.

Bulb standard dia. 3, 6 or 8mm. (Depends of temperature ranges)

Standard capillary length 300 mm or 1500 mm

Main references with 170mm arm

Damper disc diameter Capillary length

Temperature ranges (°C) 


(bulb dia. 6mm)


(bulb dia. 8mm)


(bulb dia. 6mm)


(bulb dia 3 mm)

80 mm 300 mm WQD0440AC60080G0 WQD0440AC80080G0 WQD3090AC60080G0 WQD50C0AC30080G0
80 mm 1500 mm WQD0440AO60080G0 WQD0440AO80080G0 WQD3090AO60080G0 WQD50C0AO30080G0
120 mm 300 mm WQD0440AC600C0G0 WQD0440AC800C0G0 WQD3090AC600C0G0 WQD50C0AC300C0G0
120 mm 1500 mm WQD0440AO600C0G0 WQD0440AO800C0G0 WQD3090AO600C0G0 WQD50C0AO300C0G0

Printed knobs

Many other printed knobs available, see our catalogue #1


2D&3D Drawing