Automatic freeze-proof drain system

A system to control the operation by a battery, that is connected by a battery to an AC power source, of power-operated drain valve means having first and second terminals that when exclusively signalled operate the valve means to open and close, respectively, its valve connected to the low end of piping connected to a higher tank containing liquid, said system comprising:

• temperature-responsive means having a first terminal connectable to one terminal of the battery, and second and third terminals connectable exclusively to the first and second terminals, respectively, of the valve means;
• and
• power-responsive means connectable to the AC power source, connected to the battery charger, and connected to said temperature-responsive means,
• said temperature-responsive means and said power responsive means being constructed and operatively connected to each other in a manner so that, when said temperature-responsive means is connected to the battery and to the first and second terminals of the power-operated valve means and said power-responsive means is connected to the AC power source,
• a signal is provided to the first terminal of the valve means to open automatically its valve from said second terminal of said temperature-responsive means, only when the latter means senses a temperature at or below a predetermined temperature and does so regardless of the condition of the power-responsive means, and
• a signal is provided to the second terminal of the valve means to close automatically its valve from said third terminal only when both the latter senses a temperature above that predetermined temperature and the power source is on to provide power to said power-responsive means.