The gas-fired automatic circulating water heater(s) shall be A. O. Smith XPPLUS model PWH_____________ 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 ratio of _____:1 (use 10:1 PWH models 1000 thru 1700, use 20:1 PWH models 2000 thru 3400). 2) The water heater shall bear
the ASME “HLW” stamp and shall be National Board registered (CRN in Canada) 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 a dual burner multi-pass design with three sets of helical wound 316L stainless steel water tubes that completely encircle dual combustion chambers for maximum efficiency. 2) There shall be no bolts, gaskets or “O” rings in the header configuration. 3) The heat exchanger shall be removable and replaceable as a single component 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 and wired all bronze circulating pump(s). 2) The pump(s) shall be interfaced with and managed by the water heater’s control and cycled as needed for most efficient operation.
Burners: 1) The water heater shall have (two/four) modulating burners capable of modulating between 20% and 100% fire while providing smooth starts and clean combustion. 2) Each 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 the Sola control with a multi-colored LCD touch screen display. 2) The control shall provide intuitive user operation and setup of the water heater. 3) The control will cascade/sequence, rotate and modulate the water heater’s multiple burners providing an overall turndown rate of (20/10):1. 4) The control shall display current inlet, outlet, and tank temperatures along with current firing rate for each burner. 5) Data logging with run time/number of cycles and all faults shall be recorded. 6) The water heater shall be BMS ready with factory standard with onboard MODBUS protocol connections. 7) 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. 8) The tank temperature set point and set point differential shall be adjustable and shall be maintained within +/-1 degree. 9) Night temperature setback shall be standard. 10) Redundant flow and low water protection shall be provided with factory installed and wired LWCO and flow switch(s). 11) Redundant ignition controls (one per burner) shall allow individual burner operation. 11) Factory installed Alarm Buzzer will be provided along with dry contacts for remote alarm if desired.
Frame and Jacket Design: 1) Shall be constructed of a rugged all welded extruded aluminum alloy frame with heavy gauge steel removable jacket panels that allow easy access and service. 2) The jacket panels shall be painted on both sides with a high quality powder coating that is approved for outdoor use. 3) Primary/main service access shall be provided by a latched and hinged stainless steel access door(s) that provides access to most electrical and serviceable components from the front of the unit.
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 CPVC or a combination of CPVC and PVC venting materials using CPVC for first 10 feet and PVC thereafter. 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
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