Duct frost protectionostat FST-K
temperature Temperature

Duct frost protection thermostat THERMASREG® FST-K

Product group: WG02

In Stock

Usually ships in 1 to 3 days
123,71 €
147,21 € incl. VAT + shipping


Duct frost protection thermostat THERMASREG® FST-K
Mechanical frost protection thermostat/ frost monitor THERMASREG® FST-K with switching output, duct tube monitored across the entire length, with automatic reset or with mechanical locking, with / without optional manual reset.
The frost protector is suitable for air side temperature monitoring at heat exchangers and heating
registers to prevent freezing up and to avoid frost damage, e.g. in ventilation and air conditioning ducts. The FST-K is intrinsically safe and is equipped with sensor breakage detection. In the event of damage to the capillary membrane system, the frost sensor automatically switches to the heating function. The scope of delivery includes the mounting flange MF-14-K.

Technical details

Operating difference
2 ± 1 K (3.6 ± 1.8 °F)
Switching capacity
10 (2) A, AC 250 V;
because of gold-plated switching contacts
also switching of signal voltages < 24 V
dust-proof micro switch
as single-pole potential-free changeover contact
± 0.5 K (± 0.9 °F)
Setting range
–10...+15 °C/ +14 °F...+59 °F,
factory setting to w = +5 °C (+41 °F)
Ambient temperatures
maximum operating temperature: +70 °C (+158 °F)
minimum operating temperature: w + min. +2 °C (min. +3.6 °F)
storage/ transport: –30...+70 °C (–22...+158 °F)
capillary: max. +150 °C (+302 °F)
Permissible medium
Process connection
by mounting flange, plastic
(included in the scope of delivery)
Protective tube
metal, material CuZn37 (2.0321),
Ø 14 mm, NL = 205 mm
Electrical connection
0.14 - 2.5 mm²
via terminal screws
plastic, UV-stabilised,
material polyamide, 30 % glass-globe-reinforced,
colour traffic white (similar to RAL 9016)
Housing dimensions
108 x 70 x 73,5 mm (Thor 2)
Cable gland
M 20 x 1.5; including strain relief
Other materials
mechanical sheet metal parts: galvanised steel
capillary tube: copper
capillary tube filling: R 507
switching contacts: Ag/ Ni (90%/ 10%) gold-plated (3 m)
Protection class
I (according to EN 60 730-1)
Protection type
IP 65 (according to EN 60 529)*
CE conformity,
EMC directive 2014/ 30/ EU,
low-voltage directive 2014/ 35/ EU
Contact C - 2: danger of frost/ sensor breakage
Contact C - 3: normal operation