Freeze Protection Purge Valves 35 Degree
Our Freeze Protection Purge Valves have a high temperature plastic body, ½ male threaded connection. 5/8 ID anti-siphon discharge port, 150 PSI maximum operating pressure.
Solar thermal collectors can easily reach internal temperatures down to about 10 degrees below the outside ambient air temperature. Open Loop Solar Systems typically require our VTC-55045 45°F valve to ensure proper protection from freezing.
Batch or Integrated Collector Storage (ICS) systems such as the SunEarth Copper Heart™ have a significantly larger volume of stored water and will not freeze as quickly as an Active Open Loop Solar System, in this case, they can typically utilize our VTC-55035 35°F valve.
What causes this phenomenon? It is known as night-sky emissivity. The emissivity of any material is the ratio of energy radiated by the material, in this case you’re your solar collector, to energy, either radiated or absorbed by a black body, in this case the night sky itself. This then is a measure of the solar collector’s ability to absorb and radiate energy.
Since solar collectors are coated with a black surface they are purposefully designed to be very good at conducting and emitting energy so, when the outside air temperature drops, the surface of the solar collector begins to emit energy to the night sky. When the atmosphere is clear with no clouds, this transfer of energy is accelerated.
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