Self-Operated Valve provides temperature control.
Press Release Summary:

Operating without external power source, ¾ in. TM Valve can be set for opening at any temperature from 35–255°F. Freeze Protection applications operate with valve starting to open at 39°F and fully opening at 35°F. Unit will start to close at 38°F and fully close at 42°F. Available in brass or stainless steel, TM Valve is suited for safety showers, solar panels, and condensate systems.
Original Press Release:
TM Valve for Temperature Control
The TM valve is a self-operated valve that requires no external power source. The ¾ inch valve can be used for many different applications. Freeze Protection for safety showers, solar panels, condensate systems, to mention a few.
The TM valve can be set for opening at any temperature between 35°F [1.6°C to 255°F [124°C. Freeze Protection applications operate with the TM valve starting to open at 39°F and fully opening at 35°F. The TM will start to close at 38°F and fully close at 42°F
The ¾ TM is light weight 12oz. and is available in brass or stainless steel.