Two-phase frost protectionostats FS-20
temperature Temperature

Two-phase frost protection thermostats THERMASREG® FS-20

Product group: WG02

In Stock

Usually ships in 1 to 3 days
263,70 €
313,80 € incl. VAT + shipping


Two-phase frost protection thermostats THERMASREG® FS-20
Electronic THERMASREG® FS-20 frost protection thermostat or frost monitor with switching relay output, continuous temperature and valve output (summation output 0–10 V) and control and cascading output (0–10 V), optionally with connection for a heating element, in an impact resistant plastic housing with quick-locking screws, with display by default and a fully active sensor rod made of copper.

The frost monitor is used to monitor air conditioning systems, heat exchangers, heating registers and similar systems, and protects against frost damage and freezing. Limit value underrun is detected at the coldest measuring point of the capillary tube. The sensor rod is active along its entire length. The device uses internal diagnostics to detect capillary breakage, power failure or electric damage to the sensor as errors, and the relay switches to frost automatically.
The innovative 2-phase frost protection thermostat enables a simple combination of several devices (cascading) for on-demand, comprehensive frost monitoring. The delivery scope includes a set of MK-05-Kmounting clamps for expert attachment of the sensor rod.

Technical details

Voltage supply
24 V AC/ DC (± 10 %)
Load resistance
RL > 50 kOhm
Switch-on start-up time
< 1 min
Response time
t90 < 5 s
1 x 0 -10 V control input DDC
1 x 0 -10 V ascading input
1 x 0 -10 V output temperature (corresponding to 0...+15 °C)
1 x 0 -10 V output valve
(frost signal with control voltage and cascading)
1 x potential-free changeover contact (24 V),
range of adjustment 0...+15 °C
Measuring range
0...+15 °C
typically ± 1 K (at +10 °C)
Ambient temperatures
Sensor and capillary tube: –20...+60 °C
(capillary tube at a distance of > 20 cm from the housing)
Housing: –15...+50 °C
Storage/ transport: –30...+70 °C
Process connection
by mounting clamps MK- 05 - K
(included in the scope of delivery)
Electrical connection
0.14 - 1.5 mm² via terminal screws
plastic, UV-stabilised,
material polyamide, 30 % glass-globe reinforced,
with quick-locking screws
(slotted/ Phillips head - combination),
colour traffic white (similar to RAL 9016),
housing cover for display is transparent !
Housing dimensions
126 x 90 x 50 mm (Tyr 2)
Cable gland
M 16 x 1.5, including strain relief, exchangeable,
max. inner diameter 10.4 mm
Sensor and capillary
Copper sensor rod, length of 3 m or 6 m,
active along the entire sensor length,
min. response length of 25 cm
Hysteresis of switching step
Permissible air humidity
< 95 % RH, non-precipitating air
Protection class
III (according to EN 60 730)
Protection type
IP 65 (according to EN 60 529)*
CE conformity,
electromagnetic compatibility according to EN 61326,
according to EMC Directive 2014/ 30/ EU
display with illumination, three-line, cutout approx. 70 x 40 mm
(W x H), for displaying the actual temperature, measuring
range overrange/underrange of the set switch point (frost
protection temperature), and alarm indicator for "frost" or
"error" (capillary breakage, overvoltage/undervoltage)
Internal diagnostics
Error 1 in case of cable / capillary breakage
Error 2 in case of undervoltage / overvoltage
(relay automatically switches to frost)