Vernatherm Freeze Protection Valve Model KC4500-00, 35F 
Discharge
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WARNING: See critical 
warning below relating to proper selection of valve model related to 
application. 
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Keep your solar collectors and exposed pipes from freezing with the 
Vernatherm solar freeze protection valve
The Vernatherm valve contains a thermal actuator that opens the valve when 
the temperature approaches freezing and re-closes it upon warm up. This is a 
continuous process of modulation; cold water is discharged and replaced by 
warmer water preventing panel and piping freeze up.
This valve features a 
patented anti-seize feature which ensures longevity and durability you can 
depend on, through the years this valve will not seize due to corrosion, and 
will continue to function.
Freeze protection valves use reliable, non-electric, self-contained paraffin 
wax motors (thermal actuators) which automatically respond to temperature 
fluctuations. Usually in freeze protection applications, the valve port opens on 
temperature drop, allowing liquid that would normally freeze to be discharged 
and replaced with warmer fluid within the system.  When warmer temperatures 
are detected by the thermal actuator within, the valve will automatically close 
the valve and the discharge cycle stops.
This cycle will repeat as often as necessary to prevent freezing.  The 
amount of fluid discharged depends on ambient air temperature, and fluid 
temperature.  The system is functioning properly when fluid is being 
discharged from the valve in near freezing conditions. The Vernatherm valves 
features sets these valves apart from the competition!
Product Features
• ˝" Male NPT Fitting 
• Anti-seize feature ensures longevity and 
durability
• 
Anti-insect design prevents any insect from making this valve 
   
its home and causing a failure
• Compact 
design for easy install - weighs only 4oz
• UV resistant body 
material
• Stainless steel inlet 
debris screen
• Discharge temperature set to 35F
• Internal filter screen
• FDA and NSF listed materials
• 100 psi maximum operating 
pressure
• Complete 
mechanical operation
• Tamper resistant design
• Corrosion resistant 
materials
• Non-electric 
function
Product Application: Solar Domestic Water Heating 
System
Product Function: Protects solar collectors and 
exposed piping from freezing 
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A 
typical solar domestic water heating system components and layout is shown 
below.

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Download » Vernatherm Valve Data Sheet
NOTE: During cold weather, it is normal for the valve to 
dispense water from its discharge port even when ambient air temperatures are 
several degrees above 
freezing.
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Product Warranty: 1 Year Manufacturer Warranty
Product Manufacturer: Rostra Vernatherm, LLC 
WARNING: Solar collectors can reach 
internal  temperatures up  to 10 degrees below the outside ambient air 
temperature.  Standard Active Open  Loop Solar Systems typically require a 45F 
valve to ensure  proper protection.  Passive Batch or Integrated Collector 
Storage (ICS) systems  such as the  ProgressivTube have a much larger volume and 
mass of stored water,  and will not  freeze as quickly as a Active Open Loop 
Solar System, therefore  they can  typically utilize a 35F valve. 
This 
condition results from a  phenomenon  known as "night-sky emissivity". The 
emissivity of a material is the  ratio of  energy radiated by the material 
(solar panel) to energy radiated (or  absorbed)  by a black body (the sky); it 
is a measure of a material's ability to  absorb  and radiate energy. 
Since solar collectors are coated with a  black  surface they are very 
good at conducting and emitting energy. When the  outside temperature approaches 
freezing, the surface of the solar collector  begins to  emit energy to the 
night sky. When the atmosphere is clear with no  clouds, the  transfer of energy 
is accelerated. 
In layman terms, this  means that on  a cold clear 
night, the water in the solar panel can be up to 10  degrees colder  than the 
outside temperature. A Freeze Protection Valve needs to  begin opening  when the 
outside temperature drops to 42 degrees and below. As the  temperature  drops 
from 42 to 32 the volume of water discharged from the valve  increases.  
Consult the owner's manual of your collector and/or system to  determine 
 the correct valve model to use; Solar Direct and/or The Energy  Supermarket 
 makes no claim as to the correct valve to use, and/or its usage and  
application; and assumes no liability for damages resulting from correct or  
incorrect use of this product. 
WARNING: Do  
not expose valves to temperatures above 300F (148.8c) as this may damage the  
valve.
 
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