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Seisco Tankless Electric Water Heater. Application: Whole-House. Model RA-28, 240 Volt - Free Shipping in Contiguous US *Out of Stock*
   Model: RA-28
Seisco Tankless Electric Water Heater. Application: Whole-House. Model RA-28, 240 Volt - Free Shipping in Contiguous US *Out of Stock*
Base Price:  $812.70
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    seisco tankless heaterSEISCO Tankless Electric Water Heater Model RA-28, 240 Volt

    The tankless water heater that others can only claim to be!

    After 14 years of research and testing, the SEISCO, whose technology has earned its developer 5 separate U.S. and many additional foreign patents, is recognized as the STANDARD for all tankless water heaters.

    The SEISCO tankless water heater has earned International recognition for providing the highest level of temperature control performance, reliability and safety in its operation over any tankless water heater anywhere in the world today.

    A four-chamber model designed generally for domestic water heating in whole house and booster applications.

    Seisco RA-28
    The RA-28 is the most popular residential model for providing a continuous supply of hot water for as long as you need it. Sized to replace a 50 gallon tank water heater, providing endless hot water for most applications. Ideal companion to Solar and Geothermal passive heat recovery systems. (Minimum 150 AMP Whole House Electrical Service recommended)

    This on-demand tankless water heater is a powerful replacement for traditional tank-type heaters and is the enabling technology for use as back-up to active renewable energy systems such as solar and geothermal water heating systems. The temperature activated control works effectively in re-circulating systems and in combination with tank-type heaters.

    SEISCO Tankless Water Heater Specifications
    RA-28 4 Chambers
    7000 watts x 4
    95 °F @ 2.0 GPM
    76 °F @ 2.5 GPM
    64 °F @ 3.0 GPM
    48 °F @ 4.0 GPM
    50 °C @ 8 L/min
    40 °C @ 10 L/min
    33 °C @ 12 L/min
    25 °C @ 16 L/min
    Size HxWxD
    15x 15x 6 in
    40x 40x 16 cm
    Plumbing fittings
    3/4-in NPT nipple x 2
    Shipping weight
    23 lbs / 10.5 kg
    A (max)
    50 / 60
    30A x 4


    To see all models, please click here

    Product Benefits:
    Continuous and Endless Supply of Hot Water
    Space Savings
    Safety and Health Benefits
    Smart Technology
    No Maintenance
    Environmental Benefits

    Product Features:
    UL 499 Approval Listing for Water Heating Applications
    Works with tubing and manifold systems
    No minimum flow activation required
    Built-in DSM Utility Integration option
    Compatible with Home Energy Management Systems
    No moving parts
    Very small & compact
    Light weight modular construction
    No restriction to flow
    Standard 3/4 inch plumbing connections
    Microprocessor digital control
    Power sharing & variable power control technology
    Continuous venting
    Heats continuously only when needed, no storage
    Redundant safety devices
    High performance polymer nylon chamber material
    Built-in Leak detector and alarm
    Rust & corrosion resistant

    download pdf Seisco Warranty

    4 Chambers
    The same advanced microprocessor technology and thermoplastic construction are used in both 2 Chamber and 4 Chamber models, therefore, many of the parts are interchangeable. There are no moving parts or flow restricting devices used in Seisco heaters.

    Flow/No Flow Detection
    Seisco uses a unique flow/no flow detection system utilizing temperature sensors for flow detection. In standby, the heater maintains a very subtle temperature gradient and flow is detected when there is a change in the gradient.

    Microprocessor Control
    The advanced microprocessor control turns the power on through a set of relays and turns the power off when flow stops. The most important feature may be the patented "Power Sharing" technology which provides for evenly distributed power to the heating elements. This in turn, helps eliminate scalding potential, scaling and sediment build-up.

    Control Logic
    The control logic allows the power level to vary which is beneficial in minimizing the use of power for periods of less demanding usage.

    Quality Construction:
    Seisco heating chambers are modular and molded of light weight thermoplastic materials. The chamber is specifically engineered for durability in harsh water heating environments and capable of withstanding extreme temperature swings and pressure changes. Heating elements, sensors and detection devices that come in contact with the water, are machined in brass or made of copper to help resist corrosion. Standard 1 inch, flanged screw-type heating elements are utilized which are interchangeable with heating elements available at local hardware stores.

    *NOTE: RA models are designed for residential applications.  If used in a commercial application, the factory warranty is voided; if used with 208 volt [AC] operation, the available voltage and therefore the temperature rise are derated by 25%. Commercial units are available with full factory warranty in 240V and 208V. [Call for details 800 333 9276]

    Seisco was designed with a complete array of dependable safety features to prevent harm to the user and the heater. There are several redundant safety features as well. 

    Dual high temperature switches on independent circuitry in addition to the control's internal high temperature shut down.

    Dual low level detectors are used to prevent dry firing of the heating elements.

    A leak detector is mounted on the casing that in the event of a leak sounds an alarm to the user.

    Electrical Surge Protection - Although the control board is protected against electrical surges, additional heater protection is achieved when the relays are opened during periods of standby, providing no path for the surge to reach the heating elements.

    Venting System - The chamber is designed with a patented venting system that continuously vents harmful gasses and air during operation.

    The microprocessor control is programmed to provide self diagnostics that significantly reduces troubleshooting and service time. In the event of a problem with the heater, the control emits a visual or optional built-in audible code.

    There is no maintenance required of the Seisco. However, there are clean-out plates below the heater chamber to allow removal of sand and grit that may build-up from a well water system.


    HELP » Contact Customer Support
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    General Information for all RA models:

    Power Rating:
    The four-chamber models contain four electric heating elements whose combined wattage is the total power rating of the heater. For instance, the standard RA-28 model contains four 7000 watt elements for a total of 28,000 watts, or 28 kilowatts (kW) of power. The two-chamber model, RA-14, contains only two 7000 watt elements for a total power rating of 14,000 watts, or 14 kilowatts (kW). However, because of Seisco's "Power Sharing" technology, the heater may not always use the maximum available power. The power output can vary with flow rate and temperature rise. Refer to the Product Specifications Table above for the maximum power ratings of each model.

    Heating Output: 
    The heating output of the Seisco is simply the total kilowatt power rating of the combined heating elements converted to BTUs using 3,413 BTU/kW. For instance, the RA-28 has a total power rating of 28 kW or a 95,564 BTU heat output rating. The four-chamber models have the higher output ratings; 61,434 BTUs for the RA-18 model, and 75,086 BTUs for the RA-22 model. The lower output two-chamber models, are; 47,782 BTUs for the RA-14, 37,543 BTUs for the RA-11, and 30,717 BTUs for the RA-9. These ratings vary with the operating voltage or service voltage to the heater. Refer to the Product Specifications Table for the BTU ratings of each model.

    Voltage Rating: 
    Seisco heaters are manufactured with common 240 volt [AC] heating elements designed for optimum operation on a standard residential 240 volt [AC] electric service. Also, the Seisco will operate at 208 VAC, a typical commercial voltage, with standard 240 VAC heating elements. However, when operating the heater at 208 VAC, the power rating and the heat output rating is significantly reduced. Seisco models can be special ordered with 208 VAC heating elements to help maximize the power and heating output. Refer to the Product Specifications Table above for details on the various voltage ratings.
    Maximum Current Rating:
    Each Seisco Model has a maximum electrical current rating [or amp rating] equivalent to the sum of the heating element ratings. For example, a four-chamber model, RA-28, operating at 240 VAC has four heating elements, each with a maximum rating of 29 amps. The maximum current rating or total current rating of the RA-28 is therefore 116 amps or the sum of the four heating elements. However, because of Seisco's "Power Modulating Technology", the actual current measured during relatively low flow rates and/or low temperature rises can be less than the maximum rating of the heater during operation. Refer to the A [max] or maximum amp rating under "Electrical" in the Product Specifications Table above for each model.

    Temperature Rise:
    The temperature rise must be determined in order to help choose the appropriate Seisco heater. The rise can be determined by knowing the input water temperature and the desired output temperature of the heater. The Seisco's output temperature is typically set for about 120 degrees F at the factory. Therefore, if the input or cold water inlet temperature is 50 degrees F, then the temperature rise is the difference or 70 degrees F. If the desired output temperature is 125 degrees F, then the temperature rise would be 75 degrees F. With the temperature rise determined, the Product Specification Table above provides the associated flow rate capacity of the various Seisco models.

    Flow Rates:
    The flow rate for each model is given in the "Temperature Rise" section of the Product Specification Table above. Along with the temperature rise, the flow rate must also be determined in order to choose the appropriate Seisco heater. The flow rate is determined by the type of faucet and also, life style. Refer to the chart below for typical faucet flow rates in the home. However, if the desired life style in the home requires running multiple faucets at the same time, then the flow rates must be added together to determine the peak flow demand. The Seisco or the possibility of multiple Seiscos should be selected to match the peak flow rate.

    Below are typical flow rates for new residential construction. There may be exceptions with new designer type fixtures and faucets. For instance, large custom body spa showers whirl pool and Jacuzzi tubs may have faucets with flow rates ranging from 7 gpm to 14 gpm. However, a combination of multiple Seisco heaters [preferably plumbed in a parallel configuration] can be installed to match these higher flow rates. The same peak design approach would be necessary for the anticipated life style of multiple flow rates occurring at the same time. Otherwise, use the table below and match the Seisco according to the peak flow and associated temperature rise of a single tub or shower.

    Typical Flow Rates in Gallons per Minute [gpm]
    Fixture Type
    Kitchen Sink
    Pantry Sink
    Laundry Sink
    Flow Rates

    MORE » Additional Product Information

    Download » Seisco Brochures, Data Sheets, Guides, Manuals

    Product Manufacturer: Seisco

    Return Policy
    All Tankless Water Heaters are tested at the factory just prior to shipment. It is the customer's responsibility to determine if sufficient electrical capacity exists to install the water heater prior to placing the order [See Tankless Water Heater Installation Guide]. Unit sizing must be determined by the customer using the temperature rise chart based on the required flow rate.

    A 20% restocking fee will be applied to returns of new units in original packaging (see policy page for instructions). The shipping cost will not be refunded. Once the Tankless Heater has been installed it cannot be returned.

    Processing and Delivery Information: Please allow Processing Time as stated above for your order, plus standard transportation delivery time. Orders placed after 2PM EST may not begin processing until the next business day. Please call for Rush Processing and/or Rush Shipping options.

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