Retain This Article for Water-Tube Condensing Boilers

1.1.1.1 MANUFACTURED UNITS

1.1.1.A. Description: Factory-fabricated, assembled, and tested, water-tube condensing boiler with heat exchanger sealed pressure tight, built on a steel base; including insulated jacket; flue-gas vent; combustion-air intake connections; water supply, return, and condensate drain connections; and controls. Water heating service only.

1.1.1.B. Efficiency Rating: Boiler shall have an 88% efficiency rating @ 180F return water temperature. Up to 99% thermal efficiency.

1.1.1.C. Warranty: 1.1.1.C.1. 20 year thermal shock warranty. 1.1.1.C.2. 10 year Non pro-rated for the heat exchanger. 1.1.1.C.3. 5 year for the burner. 1.1.1.C.4. Parts shall be 1 year for start-up or 18 months from shipment.

1.1.1.D. Heat Exchanger: 439 Stainless Steel Construction. The heat exchanger shall be inspected and tested to A.S.M.E. Section IV requirements. The heat exchanger shall be a eight-pass heat exchanger with maximum working pressure of 160 psig (1100 kPa). The heat exchanger is of cylindrical design, with integral stainless steel finned tube. Each end of the tubes shall be welded into the headers. The heat exchanger shall be all welded design. Copper tube and aluminum designs are not acceptable.

1.1.1.E. Combustion Chamber: Stainless steel, sealed.

1.1.1.F. Burner: Natural gas, forced draft design with stainless steel construction. Fuel to Air ratio shall be 1:1. Burner shall be fully modulating down to 20% input. Capable of meeting 10 PPM low NOx emissions.

1.1.1.G. Blower: Centrifugal fan to operate during each burner firing sequence and to prepurge and postpurge the combustion chamber.

1.1.1.G.1.a. Motor Sizes: Minimum size as indicated. If not indicated, large enough so driven load will not require motor to operate in service factor range above 1.0.

1.1.1.H. Gas Train: The gas train shall consist of a gas valve with a pressure regulating electro-hydraulic actuator to provide slow opening, fast closing, safety shutoff and air/gas ratio control. A factory pre-set combination metering valve and orifice shall be provided for setting combustion parameters. Provide low and high gas pressure switches. 1.1.1.H.1. Gas pressure to gas train: 7” - 14” w.c.

1.1.1.I.Ignition: Silicone carbide hot-surface ignition that includes flame safety supervision and 100 percent main-valve shutoff.

1.1.1.J. Casing: 1.1.1.J.1. Jacket: The external jacket shall be of stainless steel mirror finish panels assembled utilizing interference fit locks and minimal non-strip self tap screws. 1.1.1.J.2. Control Compartment Enclosures: NEMA 250, Type 1A. 1.1.1.J.3. Finish: Stainless Steel mirror finish 1.1.1.J.4. Insulation: Mineral-fiber insulation surrounding the heat exchanger. 1.1.1.J.5. Combustion-Air Connections: Inlet and vent duct collars. 1.1.1.J.6. Mounting base to secure boiler.

1.1.1.2 TRIM

1.1.2.A. Include devices sized to comply with [ANSI B31.1, "Power Piping [ANSI B31.9, "Building Services Piping”]. 1.1.2.B. Aquastat Controllers: Modulating Operator and high limit.

1.1.2.C. Safety Relief Valve: ASME rated.

1.1.2.D. Pressure and Temperature Gage: Combination water-pressure and -temperature gage. Gages shall have operating-pressure and -temperature ranges so normal operating range is about 50 percent of full range.

1.1.2.E. Circulation Pump: Field mounted and wired Non-overloading, in-line pump with split-capacitor motor having thermal-overload protection and lubricated bearings; designed to operate at specified boiler pressures and temperatures. Pump shall automatically come on when boiler is called for.

1.1.2.F. Drain Valve: Contractor to provide drain piping with shut off valve as required per Manufacturer.

1.1.1.3 CONTROLS Standard controls include a SOLA 7” color touch screen electronic proportional integrated combination limit/operator control accurate to 10F (0.50C) having a 4-20 mA output signal suitable for control of a variable frequency motor drive. A. This controller offers a range of operation modes which provides set point as well as modulating control. It provides the following: a. Readings of inlet and outlet water temperatures as well as flame signal. b. Operation as an auto reset limit. c. Operation as a control for inlet water temperature, outlet temperature, system temperature. d. 40F ΔT heat exchanger protection algorithm e. Available tank mounted sensor used in conjunction with inlet sensor. f. Adjustable; target temp, inter-stage differential, on delay between stages, minimum on time per stage, minimum off time per stage. g. Display of run hours for maintenance purposes. Counter wraps around at 10000 hours. h. Flame failure signal. i. Lumberg and Molex connectors for ease of service. j. Error message display in text k. Manual override of boiler input rate for combustion l. Pump exercising feature runs pump 10 seconds every three days in the event of no pump operation. B. Boiler mounted control is capable of controlling up to 8 boilers in a cascade arrangement. No wall mounted panel is required. The following components are needed for a Lead Lag setup: a. System Sensor located in the supply side of the common boiler piping. Outdoor air sensor. C. Sequence of Operation: When a boiler is set as Lead Lag Master = Enabled and Modbus address = 1, the controller of this boiler will drive the lead lag operation. The outdoor temperature sensor connected to the slave boiler 2 (ie. B-2) will be the outdoor sensor for the lead lag system. The system temperature sensor connected to boiler 1 in terminals labeled “Outdr/Sys” in the function box will be the control sensor for lead lag operation. The start/stop signal connected to boiler 1 at terminals labeled “Remote Operator” will be the heat demand input for lead lag operation. When demand for heat is present the lead boiler will start and uses the lead lag parameters for boiler modulation. a. After a period of “Interstage delay” the master boiler compares the lead lag temperature with the lead lag set point and will check if: a.i. An additional boiler is needed a.ii. Number of boilers remain the same a.iii. A boiler should stop b. Rotation: Rotation time is configurable based on equalized run time (default) or a fixed rotation schedule. c. Interstage Delay: The length of time to wait between requesting a slave SOLA to fire and detecting that it has failed to start. (Default: 2 minutes) d. Base Load Rate: When a call for heat is initiated the lead boiler runs at the desired base load rate (Default: 80%) and continues to operate in this fashion based on the above 3 scenarios. If the lead lag temperature is not satisfied a second boiler is fired at they would both operate at 80% fire rate.

1.1.3.A. Safety Controls:

1.1.3.A.1. High Cutoff: Manual reset stops burner if operating conditions rise above maximum boiler design [210F] 1.1.3.A.2. Low-Water Cutoff Switch: Electronic probe shall prevent burner operation on low water. Cutoff switch shall be manual reset type. Field wired and mounted 3 feet above the boiler. 1.1.3.A.3. Blocked Inlet Safety Switch: Manual-reset pressure switch field mounted on boiler combustion- air inlet. 1.1.3.A.4. High and Low Gas Pressure Switches 1.1.3.A.5. A flow switch shall be provided. Factory piped.

1.1.3.B. Building Automation System Interface: Factory install hardware and software to enable building automation system to monitor, control, and display boiler status and alarms.

1.1.3.B.1. Hardwired Points:

1.1.3.B.1.a. Monitoring: On/off status, alarm status 1.1.3.B.1.b. Control: On/off operation, hot water supply temperature set-point adjustment via 0- 10volt signal.

1.1.3.B.2. A MODBUS Communication Interface with building automation system shall enable building automation system operator to remotely control and monitor the boiler from an operator workstation. Control features available, and monitoring points displayed, locally at boiler control panel shall be available through building automation system.

1.1.1.4 ELECTRICAL POWER

1.1.4.A. Controllers, Electrical Devices, and Wiring: Electrical devices and connections are specified in Division 26 Sections.

1.1.4.B. Single-Point Field Power Connection: Factory-installed and -wired switches, motor controllers, transformers, and other electrical devices necessary shall provide a single-point field power connection to boiler.

1.1.4.B.1. House in NEMA 250, Type 1 enclosure. 1.1.4.B.2. Wiring shall be numbered and color-coded to match wiring diagram. 1.1.4.B.3. Install factory wiring outside of an enclosure in a metal raceway. 1.1.4.B.4. Field power interface shall be to fused disconnect switch 1.1.4.B.5. Provide branch power circuit to each motor and to controls

1.1.1.5 VENTING KITS

1.1.5.A. Exhaust: Flue shall consist of CPVC rated for a minimum of 200F. AL29-4C may also be used. Include vent terminal, roof flashing, indoor supports, vent adapter, condensate trap and dilution tank, and sealant. Install per Manufacturers recommendations.

1.1.5.B. Combustion-Air Intake: Intake system shall consist of PVC. Include pipe, vent terminal with screen, inlet air coupling, and sealant. Install per Manufacturers recommendations.