The gas-fired automatic circulating water heater(s) shall be A. O. Smith XP model XWH_____________ having an input rating of _________ BTU/hr and capable of supplying no less than __________GPH at a 100°F temperature rise when fired with (Natural/Propane) gas. 1) The water heater shall be capable of full modulation with a turndown ration of 5:1. 2) The water heater shall bear the ASME “HLW” stamp and shall be National Board registered for 160 PSI working pressure. 3) The water heater(s) shall be equipped with a factory-installed 125# PSIG ASME Pressure Relief Valve. 4) The water heater(s) shall be design-tested and certified to the ANSI Z21.10.3- CSA 4.3 Standards by CSA International. 5) The water heater shall operate up to 96% thermal efficiency at full fire as certified with AHRI. 6) The water heater shall be certified for indoor installation and approved for installation on combustible floors.
The heat exchanger: 1) Shall be constructed of 316L stainless steel 2) There shall be no bolts, gaskets or “O” rings in the header configuration. 3) The fully condensing heat exchanger shall be designed to allow all condensate to be drained from the bottom of the heat exchanger to ensure that condensation does not collect or interfere with good water heater operation due to long periods of operation in the condensing mode. 4) The low water volume heat exchanger shall be immune to thermal shock. 5) The entire heat exchanger shall carry a five (5) year warranty.
Water Heater Pump: 1) The automatic circulating water heater(s) shall be supplied with a factory-sized all bronze circulating pump(s) sized for 50 equivalent feet of piping. 2) The pump shall be interfaced with and managed by the water heater’s control and cycled as needed for most efficient operation.
Burner: 1) The water heater shall have a modulating burner capable of modulating between 20% and 100% fire while providing smooth starts and clean combustion. 2) The burner shall be a premix design, constructed of high temperature stainless steel and utilize a woven metal fiber mesh covering, be warranted for 5 years, and fire in a radial 360-degree flame pattern. 3) Burner ignition shall be by direct spark with flame monitoring via a flame sensor.
Water Heater Controls: 1) The water heater shall feature a touch screen display. 2) The control shall provide intuitive user operation and setup of the water heater. 3) The control shall display current inlet, outlet, and tank temperatures. 4) Data logging with run time/number of cycles and all faults shall be recorded. 5) The water heater shall be BMS ready with factory standard with onboard MODBUS protocol connections. 6) A remote tank temperature sensor shall be shipped loose with the unit to be installed in the storage tanks and allow remote tank temperature control and monitoring at the water heater. 7) The tank temperature set point and set point differential shall be adjustable and shall be maintained within +/-1 degree.
Venting: 1) The water heater shall be certified for direct horizontal through-the-wall venting or direct vertical venting; in addition to sidewall or conventional vertical venting. 2) The water heater shall be capable of horizontal sidewall or direct venting up to 100 equivalent feet without the aid of any optional sidewall vent fans or blowers. 3) The water heater shall be CSA approved for venting with PVC vent pipe. In addition the water heater shall be approved for use with UL approved AL29-4C stainless steel venting materials where local codes may require.
Standards: 1)The water heater shall have an independent laboratory rating for Oxides of Nitrogen (NOx) to meet the requirements of South Coast Air Quality Management District in Southern California and the requirements of Texas Commission on Environmental Quality. 2) The water heater shall built to and meet the ASME – CSD-1 code requirements as factory standard. 3) The water heater shall be compliant with California Code, Factory Mutual, Massachusetts Code and Kentucky Codes and standards.
Factory Start-Up: 1) The water heater manufacturer shall furnish, at no additional charge, the complete certified factory start-up that is required for activating the warranty and ensuring proper operation.