Thermostats

Frost Protection Thermostats

Frost Protection Thermostats

A frost protection thermostat is a safety device whose capillary sensor is spread across the air outlet face of an AHU water coil and gives a contact when temperature falls below the set value at any point.

It is used on fresh-air AHUs to stop the fan, close dampers and open the valve to prevent the heating coil from freezing. Setting range and capillary length are chosen per model.

Capillarysensing along the surface
Frost protectioncoil safety
Contactalarm / control
Settingdepending on model
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Main Applications

  • AHU heating coils
  • Fresh air handling units
  • Heat recovery coils
  • Rooftop air conditioning units
  • Cold climate HVAC systems
  • Building automation safety circuits

Technical Data

TypeCapillary frost protection thermostat
SensingBy the coldest point along the capillary (depending on model)
Capillary lengthDepending on model
Setting rangeDepending on model
ContactDepending on model (SPDT common)
ResetAutomatic or manual (depending on model)
Protection classDepending on model
MountingOn the AHU casing, capillary in front of the coil

Material Options

PartAutomatic resetManual reset
After trippingReturns by itself as temperature risesManual reset needed
Typical useFrequently cycling systemCritical coil protection
ContactDepending on modelDepending on model
CapillaryDepending on modelDepending on model

Which material? The capillary should be spread in a zigzag to represent the whole coil face; single-point measurement can miss freezing risk. Setting and contact values are confirmed per model.

Advantages

Protects the Coil

  • Prevents frost damage

Surface Sensing

  • Along the capillary

Automation-Ready

  • Contact output

Easy Mounting

  • On the AHU casing

Construction and Design Features

  • Capillary sensor
  • Setting knob
  • Contact assembly
  • Mounting bracket

Send the coil dimensions, capillary length and contact needs; we will confirm a suitable frost protection thermostat.

How to Choose?

  1. Determine capillary lengthChoose a length that covers the coil face.
  2. Mounting and ambientCheck mounting conditions inside the AHU.
  3. Set valueDetermine the setting range for the frost threshold.
  4. Reset and contactChoose automatic / manual reset and contact type.

Complementary Products

Electric Actuators Proportional Control Valves Temperature Measurement and Control Equipment HVAC Measurement and Control Equipment Thermometers Circulation Pumps

Why ORFA?

Since 1985Over 40 years of experience in supplying industrial piping equipment.
Technical ConsultancyTechnical support on frost protection capillary layout.
Delivery from StockFrost protection thermostats are shipped from stock.
Compatibility CheckCompatibility with Proportional Control Valves is checked for the coil valve.
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