What Is an Enclosure Cooling Thermostat? Types and Selection Criteria
An enclosure cooling thermostat closes its NO contact to run the filter fan when the panel temperature exceeds the set point and stops the fan when it falls.
An enclosure cooling thermostat is a thermostat that closes its NO (normally open) contact to switch on a filter fan or an alarm when the temperature inside the panel exceeds the set point, and stops the fan when the temperature falls. In panels with heat-producing devices such as drives, power supplies and contactors, it makes the fan run only when needed instead of continuously. Mechanical models sense temperature with a bimetal element and need no supply.
Types
| Type | Contact | Catalog example |
|---|---|---|
| KTS 011 type mechanical thermostat | NO, blue housing, 0–60 °C setting | Gwest 6681, Isıso KTS-011, KSN6052 |
| Schneider Electric simple thermostat | NO, blue housing, 0–60 °C setting | NSYCCOTHO |
| Changeover (reverse) contact thermostat | 1 NO/NC, +5–60 °C setting | Schneider Electric NSYCCOTHI |
On the changeover model the NO terminal is used for a fan and the NC terminal for a heater; the terminal you wire decides the thermostat's function.
Selection criteria
- Contact type: Fan and alarm circuits use an NO contact. A heater needs an NC heating thermostat.
- Set point: Choose a setting below the highest ambient temperature allowed by the devices in the panel. If the panel also has a heating thermostat, the cooling setting must stay above the heating setting.
- Contact load: A fan is an inductive load; go by the inductive rating in the datasheet. The NSYCCOTHO datasheet gives 10 A resistive and 2 A inductive (cosφ 0.6) at 250 V AC, and 30 W for DC. On a 24 V DC fan, 30 W means about 1.25 A. With several fans or a large fan, the thermostat drives a relay or contactor.
- Voltage: Mechanical thermostats are used up to 250 V; a 400 V fan is not connected to the thermostat directly, a contactor goes in between.
- Placement: Fit the thermostat in the upper part where warm air collects, away from the fan inlet and the heater.
Common mistakes
- Connecting a heater to a cooling thermostat: The heater runs as the panel warms up and stops in the cold.
- Setting the heating thermostat above the cooling thermostat: Heater and fan run at the same time.
- Placing the thermostat in the cool air blown by the fan: The thermostat stops the fan before the rest of the panel has cooled.
- Connecting a 400 V or high-power fan directly to the contact: The contact overheats, welds or fails early.
Cooling thermostats in the catalog
The Cooling Thermostats category has 5 active products:
- KTS 011 type NO thermostat (3): Gwest 6681, Isıso KTS-011 and KSN6052; the price is shown on the product page.
- Schneider Electric (2): NSYCCOTHO NO thermostat and NSYCCOTHI changeover thermostat; sold with a lead time, use the contact options on the product page for a price.
NC models are in Heating Thermostats, and the fans the thermostat switches are in the Fan Filters and Fans categories.
Frequently asked questions
What temperature should an enclosure cooling thermostat be set to?
There is no single value. Choose a setting below the highest ambient temperature in the datasheets of the devices in the panel and, if there is a heating thermostat, above its setting.
What is the difference between KTS 011 and KTO 011?
KTS 011 is a blue NO cooling thermostat that runs the fan. KTO 011 is a red NC heating thermostat that runs the heater.
Can the thermostat run the fan directly?
Yes, if the fan current is below the contact's inductive rating; check the fan current on the product page. With a large fan, several fans or a 400 V fan, the thermostat drives a contactor.
What is a changeover (NO/NC) thermostat for?
The same housing works as a fan or a heater thermostat depending on the terminal wired. It suits panel builders who want to stock a single type.