Check valve and spring to prevent forward and reverse thermosiphoning in solar collector systems

Abstract

A freeze protection system allows the working fluid contained in the communicating tubes of the solar collector to drain from both the input and output tubes of the collector when a first predetermined temperature of the working fluid is detected and to fill the collector via both the input and output tubes when a second predetermined temperature is detected. The invention includes valve mechanism, of the spool valve variety, that communicate the working fluid to be heated to the collector and therefrom to a storage tank, a valve actuator and a sensor. The actuator moves a valve element from a first position for communicating working fluid to be heated from a source to the input tube of the collector and for communicating heated working fluid from the output tube of the collector to a storage facility to a second position for interrupting fluid communication from the source to the collector and for communicating both the input and output tubes of the collector to a drainpipe--draining the collector of working fluid--when the first predetermined temperature level is detected by the sensor. Upon detection of the second predetermined temperature level the sensor causes the actuator to return the valve element to the first position via an intermediate position that closes the drainpipe and temporarily communicates the working fluid to both the input and output tubes of the collector. As part of the invention, a unique holder of a thermally conductive material is provided to hold the power and heater parts of the actuator. Additionally, a spring-loaded ball-check valve is provided to prevent both forward and reverse thermosiphoning and the end of the spool on the valve is notched to create asymmetric flow patterns which prevent spool vibration during displacement of the spool from its normal operating position. This invention relates to apparatus for draining and working fluid from solar collectors to avert freezing and consequent freeze damage and particularly to a freeze protection valve operable from a thermostatic actuator.

Dependencies are inferred from the claim text.