The V43/243 valves are refrigerant-actuated units that require only system refrigerant head pressure to operate. The valve does not require electrical power: if you make the inlet and outlet water lines and refrigerant head pressure connections, the valve functions.
Refrigerant head pressure drives a built-in pilot valve that operates the main valve. Water and spring pressures are the main valve's opening and closing forces.
The main valve seat disc assembly is suspended on a heavy-duty rubber diaphragm, eliminating any close-fitting or sliding parts. This reduces friction within the valve, facilitating more reliable control. This also reduces the chance of the valve stem sticking in dirty water conditions.