The feed forward water heaters use low pressure steam up to 15 psig to produce a maximum of 120 gpm of 180 deg oF hot water. The design of this water heater makes it a perfect application for remote locations not requiring electricity as well as for use in wash downs or laundries.
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Standard Equipment
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Operation
CEMLINE® Feed Forward Water Heaters can supply domestic hot water with a temperature range set point of 105 to 180 deg F using low pressure steam (2-15 psig). Models are available for flow rates from 15 to 120 gallons per minute.
The CEMLINE Feed Forward Instantaneous Water Heaters (FFH) use a pressure sensing blending valve to mix overheated hot water with cold water to make hot domestic water. Cold water is passed through the tubes of the heat exchanger while 2 to 15 psig steam is piped to the shell of the heat exchanger which overheats the water in the tubes. A differential pressure sensing head then blends the cold water with the over heated hot water to deliver domestic hot water at a stable temperature with an adjustable range of 105 to 180°F. FFH water heaters are not recommended for water with hardness over 140 parts per million. If water hardness exceeds 140 ppm either put a water softener in the system or use CEMLINE SEH series water heater.
The varying pressures from above and below the diaphragm of the blending valve are used to balance the differential pressure sensing head. A sensing line is run from the cold water supply to the top of the blending valve applying pressure downward on the diaphragm of the blending valve. The blended water’s pressure is applied upward upon the diaphragm of the valve from below. When the pressure on the diaphragm is even, the valve is closed and hot water is not sent out to the system.
When a demand rises in the system for hot water, the pressure of the blended water decreases. As the blended hot water’s pressure drops, the pressure on the diaphragm from the cold water becomes greater than the pressure of overheated hot water on the diaphragm. The greater pressure of the cold water pushes the diaphragm down, which pushes the stem of the blending valve down, thus opening the hot water ports on the valve allowing more overheated hot water to blend and be sent out as hot water into the system.
When the demand for hot water stops, the pressure of the blended hot water increases equaling that of the cold water, thus raising the diaphragm and the stem of the blending valve which closes off the opened hot water ports and stops the blending of hot water.
The valve allows for automatic proportioning of the hot and cold water thereby maintaining the desired set temperature even during conditions of uneven flow. The water is blended quickly,which prevent any lags in response to demand. -
Optional Equipment
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Recirculation Kit
A recirculation kit is REQUIRED if the water in the system is being recirculated. Temperature control problems will occur if the recirculation kit is not used in a recirculating system. Temperature control problems will occur if a recirculation kit is not installed in a recirculated system. The problem, recirculated water returning to the heater hot, is experienced during times of little or no hot water usage. The movement of the water through the system will cause the blending valve to sense a pressure drop and cause the valve to open and heat the hot water hotter. Eventually, the water in the system will become dangerously hot. Therefore, when recirculating water, it is essential that a recirculation kit be supplied. The recirculation kit allows for the proper mixing of hot and cold water into the system through the use of a balancing valve and a 3-way thermostatic valve. The mixing valve allows for the diverting of hot water away from the heater if the system temperature is already at the heaters set point. For safety purposes the mixing valve is non-adjustable, preventing accidental changes in the hot water system temperature thus preventing any over-temperature situations. See the operation schematic below.