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 FFH Series Tech Info
  Steam Fired Instantaneous
Feed Forward Water Heaters


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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.

The blending valve is safe and will shut-off in situations of loss of cold water pressure. Should the movement of the blending valve be restricted by foreign debris carried in the water,a yielding spring arrangement allows the diaphragm and stem to move up,uncovering a heat damper in the characterized blending valve. This damper allows cold water to enter the blended mix,eliminating the possibility of over-heating or scalding.

Moving the adjustment rod on the stem of the blending valve easily sets the temperature of the FFH allowing for an easy startup of the unit. The domestic hot water temperature range is 105 to 180°F.

CEMLINE FFH units can be completely packaged allowing the customer to receive a water heater that only requires connections to be made to the cold water inlet,hot water outlet,steam in,and condensate out. This is the ideal way to install an FFH heater as it reduces piping times at the job site.

STANDARD EQUIPMENT

  • Pressure Sensing blending valve
    FFH heaters use a differential pressure sensing blending valve that blends cold water with the over heated hot water to deliver domestic hot water at a stable temperature with an adjustable range of 105°F to 180°F.

  • Helical Wound Coil
    The helical wound coil is designed to provide the maximum heat transfer from the low pressure steam (2-15 psig) on the shell side to the water locating within the tubes. The standard coil material is copper, however the coil is available in 90:10 copper nickel, and admiralty brass. The coil has a pressure rating of 150 psig.
  • Ductile Iron Vessel
    The ductile iron vessel has 2-15 psig saturated steam. The vessel is rated at 75 psig working pressure.

  • Structural I-beam support Skid Base
    CEMLINE heaters are mounted on structural I-Beam support skids designed as a permanent base. This skid is pre-engineered to allow correct support for the heater.

  • Water Pressure Gauge
    CEMLINE packaged heaters are supplied with a large, easily readable pressure gauge.
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OPTIONAL EQUIPMENT
  • Recirculation Kit
    A recirculation kit is REQUIRED if the water in the system is recirculated to the unit. The recirculation kit allows for the passing of recirculated hot water, which prevents overheated water leaving the FFH heater.

  • Packaged Unit
    Completely packaged and skidded unit. The only connections to be made are the cold water inlet, hot water outlet, steam in, and condensate out.
  • Upstream Pressure reducing Valve
     In some installations, the steam pressure supplied will be above 15 psig. In these instances, CEMLINE can provide a pilot operated pressure reducing valve (PRV) to be piped upstream of the FFH that will reduce the steam going to the unit 15 psig.

  • Insulation Cover
    The insulation cover is placed over the top of the heat exchanger to prevent heat loss of the heat exchanger. This high quality insulation is an extremely reliable means of minimizing heat loss.
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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.

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