Thermostats
Capillary thermostats for boilers, hot water cylinders, incubators, and industrial equipment: IMIT and Welko models with adjustment ranges of 0–40, 0–90, and 40–210 °C.
Subcategories
Products (10)
- IMIT 540030 TR2 Coil Heater Thermostat, 0–40°C, Dual Contact – Request a quote (out of stock)
- IMIT 541503 LS1 Spiral Heater Thermostat, Limit Safety Thermostat, 90-110°C – Request a quote (out of stock)
- IMIT 542441 TC2 Boiler Thermostat, 40-210°C – $19.94
- IMIT 542714 TLSC Boiler Thermostat, Dual, 0–90°C – $69.28
- IMIT 544610 TA Boiler Thermostat, 0-40 °C, Incubation Thermostat – Request a quote (out of stock)
- IMIT 545610 BRC Boiler Thermostat, 20-90°C, Surface-Mount – Request a quote (out of stock)
- Welko Boiler Thermostat, 0–90 °C, Dual Contact – $15.48
- Welko Chain Boiler Thermostat, Mechanical, 0-90 °C – $24.99
- Welko Dual Boiler Thermostat, 0–90°C – $32.85
- Welko Incubator Thermostat, 0-40°C – $21.02
What is a capillary thermostat?
Capillary thermostats are control devices that sense temperature via a bulb and open or close an electrical contact when the set value is reached. The bulb is connected to the thermostat body by a thin capillary tube; the fluid inside expands with temperature and moves the mechanism. They are used to control a burner or pump in boilers, to maintain a constant temperature in incubators, and for temperature control in ovens and process equipment.
Selecting by adjustment range
- 0–40 °C: Incubators, greenhouses, and low-temperature applications.
- 0–90 °C: Heating boilers, hot water cylinders, and circulation pump control.
- High ranges such as 40–210 °C: Ovens, oil baths, and industrial heating applications.
Dual thermostats combine an operating thermostat and a safety (limit) thermostat in a single body. Models designed for boiler applications are listed separately in the boiler thermostats category.
Selection and installation
The thermostat's adjustment range must comfortably cover the temperature to be controlled. The contact type (normally open, normally closed, or changeover) and contact current capacity must be selected according to the device being controlled; high-power devices should be controlled via a contactor. The bulb must seat fully in the immersion pocket at the measurement point. The capillary tube must not be sharply bent or allowed to contact hot surfaces.
Safety
Electrical connections must be made in accordance with the device's wiring diagram and with the power switched off. Safety thermostats are used to protect the system in the event of operating thermostat failure; the safety function must not be disabled.
Frequently asked questions
What is the difference between a room thermostat and a capillary thermostat?
A room thermostat measures ambient air; a capillary thermostat measures the temperature of water or an appliance via a bulb.
Which thermostat is right for an incubator?
Models with a 0–40 °C range that allow fine adjustment at low temperatures are preferred.
What does a dual thermostat do?
In addition to normal operating control, it provides a safety function that shuts the system down at excessive temperatures.
Can the capillary tube be extended?
No; the capillary length is set at the factory, and cutting or modifying it will damage the device.
How many amps can the thermostat carry?
The contact capacity is stated in the product information; use a contactor for high-current loads.
Why is the thermostat slow to activate?
The bulb may not be fully seated in the pocket, or the inside of the pocket may be dirty; check the contact surface.