The temperature regulating device in a Hubbell Instantaneous Steam water heater is a "feed forward" blending valve designed to assure safe and accurate
temperature control of the heated water for an entire range of flow capacities. A purely mechanical operation, the Hubbell blending valve will provide ± 4oF temperature control
without the use of thermostatic sensing devices.
How the Blending Valve Works:
1.
The proportioning valve plug is regulated by movement of the diaphragm, induced by pressure differentials in the sensing head.
2.
A sensing line "loads" the top portion of the diaphragm with supply line cold water pressure while blended water outlet pressure is being sensed below.
3.
Flow demand imparts a pressure imbalance above (+) and below (-) the diaphragm resulting in movement of the diaphragm and proportioning plug.
4.
The movement aligns ports in the plug with supply ports in the valve body, introducing the correct proportion of hot and cold water.
5.
This action automatically generates blended hot water through all rated flow capacities at the chosen preset temperature (± 4oF).
The integral fail-safe system permits stem travel in the event of plug restriction or parts failure, opening an auxiliary cold water port. Cold
water flooding yields cooler water, or when parts fail, no water at all.
Temperature is easily adjusted by side-to-side movement of the control rod on the valve body. Stabilization adjustments are made during initial start-up by rotation of the control rod. All settings
are locked in with a locking ring and set screw.
