SECTION 235216 CONDENSING BOILERS PART 1 - GENERAL 1.1 RELATED DOCUMENTS A. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division 01 Specification Sections, apply to this Section. 1.2 SUMMARY A. This Section includes packaged, factory-fabricated and -assembled, gas-fired, fire-tube condensing boilers, trim, and accessories for heating hot water. 1.3 SUBMITTALS A. Product Data: Include performance data, operating characteristics, furnished specialties, and accessories. B. Shop Drawings: For boilers, boiler trim, and accessories. 1. Include plans, elevations, sections, details, and attachments to other work. 2. Wiring Diagrams: Power, signal, and control wiring. C. Source quality-control test reports: Indicate and interpret test results for compliance with performance requirements before shipping. D. Field quality-control test reports: Indicate and interpret test results for compliance with performance requirements. E. Warranty: Standard warranty specified in this Section. 1.4 QUALITY ASSURANCE A. Electrical Components, Devices, and Accessories: Listed and labeled as defined in NFPA 70, Article 100, by a testing agency acceptable to authorities having jurisdiction, and marked for intended use. B. ASME Compliance: Fabricate and label boilers to comply with ASME Boiler and Pressure Vessel Code. C. ASHRAE/IESNA 90.1 Compliance: Boilers shall have minimum efficiency according to "Gas and Oil Fired Boilers - Minimum Efficiency Requirements."
D. AHRI Compliance: Boilers shall be AHRI listed and must meet the minimum efficiency specified under AHRI BTS-2000 as defined by Department of Energy in 10 CFR Part 431. E. ANSI Compliance: Boilers shall be compliant with ANSI Z21.13 test standards for US and Canada. F. CSA Compliant: Boilers shall be compliant with CSA certification. 1.5 COORDINATION A. Coordinate size and location of concrete bases. Cast anchor-bolt inserts into bases. Concrete, reinforcement, and formwork requirements are specified in Division 03. 1.6 WARRANTY A. Standard Warranty: Boilers shall include manufacturer's standard form in which manufacturer agrees to repair or replace components of boilers that fail in materials or workmanship within specified warranty period. 1. Warranty Period for Fire-Tube Condensing Boilers: a. The pressure vessel/heat exchanger shall carry a 10 year from start up, nonprorated, limited warranty against any failure due to condensate corrosion, thermal shock, mechanical defects or workmanship when installed in compliance with the manufacturer s installation instructions. b. All other components shall carry a two year warranty from date of boiler start up. PART 2 - PRODUCTS 2.1 MANUFACTURERS A. Available Manufacturers: Subject to compliance with requirements, manufacturers offering products that may be incorporated into the Work include, but are not limited to, the following: B. Basis-of-Design Product: Subject to compliance with requirements, provide Viessmann Vitocrossal 300, CA3 or a comparable product by one of the following: 1. Viessmann Manufacturing Co. (US) Inc. 2. Buderus 3. Lochinvar 2.2 CONSTRUCTION A. Boiler shall be factory-fabricated, factory-assembled, and factory-tested, fire-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. [Optional] The boiler assembly may be disassembled on site for limited height and width site entrance access including jacketing, top frame, burners, and gas train componentry. B. Heat Exchanger: The heater exchanger shall bear the ASME H stamp for 160 psi working pressure and shall be National Board listed. The boiler shall use a sectional design, incorporating 2 or more boiler sections. The combustion chamber and heat exchanger shall be constructed of high grade stainless steel (SA240-316Ti) and be of fire tube design. Fire tube shall be of the Inox-Lamellar design for maximum heat and condensation for optimum energy savings. The finned heat exchanger surfaces constructed of high grade stainless steel (S43940) shall provide a self-cleaning effect while promoting clean combustion through low heat exchanger loading and a straightthrough design with minimal flue gas resistance. The flue gasses shall pass by the return water in a counter-flow direction only, for maximum heat transfer. Lifting lugs shall be provided on the heat exchangers for serviceability. C. Condensate collector. The flue gas and condensate collector shall be made of SA240 304L stainless steel. D. Pressure Vessel: Pressure vessel complete with all required inspection openings shall be constructed in accordance with ASME Section IV pressure vessel code. 1. The boiler shall be of a high mass design with a minimum water content of 108 gallons: E. Burner: The boiler shall incorporate a modulating compact pre-mix cylindrical stainless steel gas MatriX burner with a high-alloy stainless steel surface capable of operating with consistently high efficiency. The burner shall be equipped with a variable speed combustion fan for quiet and economical operation. The burner shall be constructed from high-grade, high temperature material for universal use with natural gas or propane gas. Burner ignition shall be by a direct spark ignition system. The burner shall be capable of operating at altitudes of up to 10,000 ft. (3,000 m) without change of orifices, but with the use of electronic adjustment/setting. The burner shall be capable of operating at natural gas pressures from 4 up to 14" W.C., and propane gas pressure of 10 up to 14" W.C. The burner shall incorporate the electronic high limit, and the manual reset fixed high limit. Gas train shall be preassembled and supplied with all components as required by the ASME CSD-1 Code. F. Casing 1. Jacket: The sheet metal cladding shall be easily and fully removable, allowing for easy access during servicing. 2. Insulation: The R-value of the insulation shall be equivalent to 4" (100 mm) mineral wool with nylon backing.
G. Performance Criteria 1. Heating Medium: Hot Water 2. Each boiler shall be designed for operating at: a. NG input range 250 6000 MBH b. Maximum output 2197 MBH as per AHRI test to BTS-2000 3. Boiler turn-down ratio shall be 10:1 or 15:1 dependent upon the number of boiler sections. 4. Combustion efficiency shall not be below 96.1% and thermal efficiency shall not be below 96.0% as tested to U.S. Standard ANSI Z21.13/CSA 4.9. 5. ASME maximum water temperature (Fixed High Limit): 210 F. 6. Maximum boiler operating temperature (Adjustable High Limit): 203 F. 7. The boiler shall operate without a flow switch. 8. The boiler shall weigh no less than 4388 lbs., including the burner, controls and jacketing. 9. Heat exchanger surface area shall not be less than 143.2 288.8 ft 2 dependent upon the gross BTU input of the boiler. 10. No additional safety devices shall be required to safeguard against low flow conditions. 11. The boiler shall be capable of accommodating a 50% glycol mixture. 12. The condensation rate, controlled by optimum combustion, shall be able to meet a CO 2 value of 10% through the entire firing range. 2.3 TRIM A. Safety Relief Valve: 1. Size and Capacity: 75 PSI
B. Condensate Neutralization Kit: Optional factory supplied condensate P-trap, high capacity condensate receiver prefilled with appropriate medium. 2.4 CONTROLS A. Refer to Division 23 Section "Instrumentation and Control for HVAC." B. General: The Vitotronic 300 GW6C shall be capable of operating as a standalone boiler control with outdoor reset capabilities or shall be cascadable as part of a multi boiler system (to a maximum of 8 burners/controls using the Viessmann LON protocol) for boiler set point operation without the requirement for a separate stand-alone cascade controller. [OPTIONAL] For systems consisting of greater than 8 burners/controls, and additional stand-alone cascade control shall be provided as described in Appendix A. C. In standalone operation the control unit shall provide control for a boiler with one high temperature circuit and two mixing valve circuits with the integrated mixing valve module, using digital weather responsive reset. Additional circuits shall be added with the order of an ancillary mixing valve controller and/or a custom control panel. System components shall use the Viessmann LON communication protocol. The outdoor reset supply temperature of every heating circuit shall result from the outside temperature, the set room temperature, the operating mode and the heating curve. In cascade operation each boiler is supplied with an integrated LON card for communication between boilers, via the Viessmann LON Protocol. In cascaded operation one boiler will be selected and programmed as the Lead Boiler' with the remaining boilers being programmed as Lag Boilers'. The boilers shall be operated on a set point temperature only generated through the Lead Boiler' and delivered to the cascade system via the Viessmann LON protocol. The 'lead' control unit shall provide control for a heating system with one high temperature circuit and two mixing valve circuits with the integrated mixing valve module, using digital weather responsive reset. Additional circuits shall be added with the order of an ancillary mixing valve controller and/or a custom control panel. D. The controller shall have the following features: 5 Inch color touch screen user interface. Compatible with Viessmann modulating burner. EPROM memory is maintained without main power. Control algorithms are PID-based. Quick connect plug & play system for low voltage controls. Communication with other protocols such as Modbus, BACnet and LON (Ethernet/IP) shall be available (through optional accessories gateway). E. The controller shall be factory tested and approved to CSA and UL standards as part of a package with the compatible series of boilers. F. The controller (in standalone or cascade boiler operation) shall be able to support the following output devices: (2-3) Fully modulating burners depending on unit size
(1) Modulating boiler isolation valve. (1) Boiler pump. (1) Domestic hot water pump. (1) Domestic hot water re-circulation pump. (2) Low temperature heating loop circulation pumps in conjunction with mixing valves. (2) Heating loop modulating mixing valves. G. Control Interface: The control interface shall be a digital display capable of displaying temperatures as F or C, with menu driven selection functions, with access to the following operating points: Able to display all system temperatures and set points. Displays unique fault message during an alarm. A program selection mode. Domestic hot water temperature set point adjustment. Information indicator with confirmation. Boiler operating hours display. Number of burner starts display. Operating status check. Emission/service test switch. Adjust the display contrast. Temporary occupied mode function. Slope and shift adjustment for heating curve. H. Additional Features: The controller shall have the following additional features: On/Off switch. Default factory settings reset. Operating status indication light. Tamper-proof fixed high limit (integrated in burner control). Service switch (overrides electronic high limit). Fault Indicator light. Operating condition scans. Maintenance requirement status. Relay test function. Integrated boiler flue gas temperature sensor. Participant check (LON nodes). Quick heat up and quick set-back functions. Start-up and shut-down optimization functions. Warm weather shut-down. Energy savings mode. Ability to restore the control to factory defaults. I. The fixed high limit shall have the following tamper-proof features: CSA certified burner control with integrated Electronic Fixed and Adjustable High limit sensors are used.
J. Boiler System Supply Water Temperature Control Each controlled zone shall have a calculated heating curve which describes the required supply water temperature at different outside air temperatures. The slope and shift of each heating curve shall be adjusted to fit any type of building or system. The highest required temperature of all zones shall be used together with conjunction from an optional room temperature sensor to determine the common boiler supply temperature set-point. In the unoccupied mode, the supply water temperature set-point shall be reduced by a pre-determined amount. A call for domestic hot water or an external demand signal shall override this set-point to pre-determined values. Control logic shall be equipped to protect the heating system from freeze-up if left in a standby mode during the off season. K. Domestic Hot Water Control The DHW temperature shall be controlled through starting and stopping the DHW circulation pump. An automatic or individual time program shall be selected for the control of the DHW and the DHW tank re-circulating pump. An individual time program shall enable up to four switching periods per day to be set to control the DHW heating and the DHW re-circulation pump. The DHW control sequence shall use an adaptive algorithm that takes into account the rate at which the temperature changes and whether the boiler will be required to supply heat after the DHW tank has been heated or whether residual boiler heat should be transferred to the DHW tank. Available domestic hot water strategies shall include: priority control (supply water set-point increases, the mixing valve closes and the heating circuit pumps are shut off on a call for DHW), modulating priority (the supply water set-point of the mixing valve circuits shall be reduced until the DHW supply temperature requirements have been met), or no priority at all. A frost protection function shall energize the DHW production should the supply water temperature drop below a pre-determined value. An optional second temperature sensor placed in the cold water inlet can be incorporated to determine if DHW production should begin prematurely. If required, a solar heating control strategy using an extra temperature sensor in the solar system shall be selected. L. Fault Management If a fault occurs on a boiler, the fault code shall be indicated in the display window and by the flashing red fault lamp. A compiled failure alarm contact output shall close in order to signal the alarm condition to a Building Automation System (BAS). The message shall also be broadcasted on the LON communication bus. The error history shall be saved to memory. M. Scheduling There shall be separate time schedules for central heating, DHW heating and the DHW
re-circulation pump. Each device shall be able to be scheduled to switch between occupied and unoccupied modes up to four times per day. N. Boiler Rotation (Lead Boiler) The boilers shall be rotated once a month according to an equal run-time strategy or on a schedule every 200 to 2000 hours. A dry contact shall be incorporated to make the current lead boiler the lag boiler whenever contact is closed. If the system has both condensing and non-condensing boilers, the condensing boiler shall be programmed to always be the lead. O. Auxiliary Inputs The following dry contact inputs shall be available to be wired to each boiler to control the following functions (functionality dependent on operating mode): Boiler disable. Change between modulating to staged burner control. External heat demand. Boiler sequencing. External enable. External blocking. Heating program changeover. P. Building Management System Interface The controller shall have the ability, through the use of an optional Extension Module, to accept a 0-10V signal from a Building Management System for the purpose of allowing remote control of the boiler supply water temperature set point. The controller shall be able to fully integrate with Building Management Systems running on the BACnet, Modbus, or LON (Ethernet/IP) communication protocols via a gateway. Q. Remote Communication Interface The controller shall have the ability to be connected to a phone dialer, enabling remote control of any of the functions listed in the Auxiliary inputs section. The controller shall have the ability to be connected to an Internet server interface, which shall allow access to all programming and operating parameters over the World Wide Web (when used in conjunction with BMS interface and accessory communication gateway). R. The standard control options shall be able to operate independently, or integrate with building management system protocols via an optional gateway as referenced in the control section.
2.5 ELECTRICAL POWER A. Controllers, Electrical Devices, and Wiring: Electrical devices and connections are specified in Division 26 Sections. B. Single-Point Field Power Connection: Factory-installed and factory-wired switches, motor controllers, transformers, and other electrical devices necessary shall provide a single-point field power connection to boiler. C. Electrical Characteristics CA3-2500/3000/3500/4000: 1. Voltage 120V 2. Phase: Single 3. Frequency: 60 Hz Electrical Characteristics CA3-5000/6000: 1. Voltage 208V 2. Phase: Three 3. Frequency: 60 Hz CA3-5000 and 6000 requires 208Y/120VAC 3 phase 60 HZ 4 wire (L1, L2, L3, N, G) power supply. 2.6 VENTING A. The boiler vent system shall meet Category IV venting requirements. The vent material shall be UL/ULC/CSA listed for Category IV, made of either stainless steel or polypropylene (PPs), and be water and gas tight. Sidewall venting applications shall be acceptable. B. Intake piping for all models must be of approved material and design as listed in the Installation and Operations manual. C. Boiler venting and intake piping configuration shall be installed in accordance with the Installation and Operation manual provided. D. Boiler shall come standard with a flue gas temperature sensor. E. [OPTIONAL] Common vent system must be designed and installed with Viessmann common vent system design guide and only installed when allowed to do so by local authority having jurisdiction. F. Refer to manufacturer s Installation and Operations manual for detailed venting instructions and guidelines
2.7 SOURCE QUALITY CONTROL A. Burner and Hydrostatic Test: Factory adjust burner to eliminate excess oxygen, carbon dioxide, oxides of nitrogen emissions, and carbon monoxide in flue gas and to achieve combustion efficiency; perform hydrostatic test. B. Test and inspect boilers, before shipping, according to ASME Boiler and Pressure Vessel Code. C. Allow Owner access to source quality-control testing of boilers. Notify Architect 14 days in advance of testing. PART 3 - EXECUTION 3.1 EXAMINATION A. Before boiler installation examine roughing-in for concrete equipment bases, anchor-bolt sizes and locations and piping and electrical connections to verify actual locations, sizes and other conditions affecting boiler performance, maintenance and operations. B. Final boiler locations indicated on Drawings are approximate. Determine exact locations before roughing-in for piping and electrical connections. C. Examine mechanical spaces for suitable conditions where boilers will be installed. D. Proceed with installation only after unsatisfactory conditions have been corrected. 3.2 BOILER INSTALLATION A. Install boilers level on concrete bases. Concrete base is specified in Division 23 Section "Common Work Results for HVAC," and concrete materials and installation requirements are specified in Division 03. B. Install gas-fired boilers according to NFPA 54. C. Assemble and install boiler trim. D. Install electrical devices furnished with boiler but not specified to be factory mounted. E. Install control wiring to field-mounted electrical devices. 3.3 CONNECTIONS A. Piping installation requirements are specified in other Division 23 sections. Drawings indicate general arrangement of piping, fittings and specialties. B. Install piping adjacent to boiler to permit service and maintenance.
C. Install piping from equipment drain connection to nearest floor drain. Piping shall be at least full size of connection. Provide an isolation valve if required. D. Connect gas piping to boiler gas-train inlet with unions. Piping shall be at least full size of gas train connection. Provide a reducer if required. E. Connect hot-water piping to supply and return boiler tappings with shutoff valve and union or flange at each connection. F. Install piping from safety relief valves to nearest floor drain. G. Boiler Venting 1. Install flue venting kit and combustion-air intake. 2. Connect venting full size to boiler connections. [Comply with requirements in Division 23 Section "Breechings, Chimneys and Stacks."] H. Ground equipment according to Division 26 Section "Grounding and Bonding for Electrical Systems." I. Connect wiring according to Division 26 Section "Low-Voltage Electrical Power Conductors and Cables." 3.4 FIELD QUALITY CONTROL A. Perform tests and inspections and prepare test reports. 1. Manufacturer's Field Service: Engage a factory-authorized service representative to inspect components, assemblies, and equipment installations, including connections, and to assist in testing. B. Tests and Inspections: 1. Perform installation and startup checks according to manufacturer's written instructions. Complete startup form included with Boiler and return to Manufacturer as described in the instructions. 2. Leak Test: Hydrostatic test. Repair leaks and retest until no leaks exist. 3. Operational Test: Start units to confirm proper motor rotation and unit operation. Adjust air-fuel ratio and combustion. 4. Test and adjust controls and safeties. Replace damaged and malfunctioning controls and equipment. a. Check and adjust initial operating set points and high- and low-limit safety set points of fuel supply, water level and water temperature. b. Set field-adjustable switches and circuit-breaker trip ranges as indicated. C. Occupancy Adjustments: When requested within 2 months of date of Substantial Completion, provide on-site assistance in adjusting system to suit actual occupied conditions. Provide up to two visits to Project during other than normal occupancy hours for this purpose.
D. Performance Tests: 1. Engage a factory-authorized service representative to inspect component assemblies and equipment installations, including connections, and to conduct performance testing. 2. Boilers shall comply with performance requirements indicated, as determined by field performance tests. Adjust, modify, or replace equipment to comply. 3. Perform field performance tests to determine capacity and efficiency of boilers. 4. Repeat tests until results comply with requirements indicated. 5. Provide analysis equipment required to determine performance. 6. Provide temporary equipment and system modifications necessary to dissipate the heat produced during tests if building systems are not adequate. 7. Notify Engineer / Architect in advance of test dates. 8. Perform a combustion analysis after installation and adjust gas valve per the Installation and Operations manual and note in startup report. 9. Document test results in a report and submit to Architect. END OF SECTION 235216
APPENDIX A 2.4 CONTROLS B. The stand-alone cascade control used in each of the custom control applications shall be CSA and/or UL approved for use in USA and Canada. 1. Construction: a. Control Panel: The enclosure shall be constructed of 16 ga. steel, the door of 14 ga. steel, and the sub panel of 11 ga. steel. The enclosure shall be electrostatically powder-coated with Viessmann orange, silver or white. The sub panel shall be zinc-plated. Enclosure rating shall be as follows: NEMA 1. Enclosure panel size depends on the extent of options specified. Control panel door shall incorporate a key lock. Lock to be operated with supplied key or tool. The lock shall be of sufficient size or quantity to allow panel door to close flat for proper sealing of gasket to provide a moisture and dust resistant seal. Control panel shall incorporate moisture gutter to allow accidental water splashes from entering cabinet when door closed. Control panel door shall incorporate rubber, or dense foam to provide a moisture resistant seal water from entering panel. Panel may provide opening for gland plate to facilitate hard wiring or conduit connection. Glad plate shall be supplied with one-piece gasket for moisture intrusion protection and be fastened in place with screws. b. Components Within DIN Rails Din rails shall be used where possible to facilitate mounting of internal components, including, but not limited to wire terminals, relays, fuse blocks and circuit breakers. The DIN rails shall conform to standards 46277/1, /2, /3, EN 50.022, 50.045 and 50.035. The rails shall be constructed from cold rolled steel and protected with an electrostatically applied coating. Oval mounting holes shall be provided throughout the entire length of the DIN rail. The DIN rails shall be mechanically fastened to the control panel back plate using sheet metal screws. c. Wire Terminals The wire terminals shall be suitable for environments of 5 C to +40 C, height of up to 2000m above sea level and an RH of 50% at +40 C and 90% at +20 C. The wire terminals shall be mounted on DIN rail and held in place with end bracket. The wire clamping mechanism shall be vibration resistant and of a design that locks the clamping screw from backing off. The mechanical parts of the terminals clamping mechanism shall be made of hardened steel and shall provide a gastight and vibration resistant connection. The current carrying bar of the terminal block, shall be constructed from either copper or high quality brass. Terminal blocks shall be constructed from thermoplastics such as Polymide, Wemid, and Thermoplastic polyester.
d. Wire Wire used to interconnect the panel devices shall be of stranded, TEW type and shall be rated for 105 degree C (221 degrees F) at 600VAC. Where possible, all bare stranded connections shall be terminated with stainless steel ferrules or crimp on terminals. Wire gauge shall be sized according to electrical codes to satisfy amperage demands of control and output devices. e. Wire Duct Wires used within panel, where possible, shall be run in wire duct. The wire duct shall be sized appropriately for the specific gauge and quantity of wires. Wire duct shall be made of PVC and have a continuous use temperature of 50 degrees C (122 degrees F). Wire duct shall be of wide finger/slot design to allow unobstructed interconnection between duct work and electrical components. Wire duct shall meet or exceed standards set by UL and/or CSA and conform to NFPA 79-2002 section 14.3.1 requirement for flame retardant material. f. Switch Blocks The switch block shall be either a two position On/Off or three position Auto/Off/On configuration. When configured as a two position switch, the switch block shall be comprised of one contact block. Lamp indication shall be included where necessary to indicate ON status. When switch block configured as a three position switch, the switch block shall be comprised of two contact blocks. Lamp indication shall be included where necessary to indicate ON status. The switch block shall have self-cleaning contacts and shall be rated for no less than 6 amps at 110VAC. The switch block shall be rated for an electrical life of 500 000 cycles at 3 amps. g. Relays All relays and contactors shall have a minimum life expectancy of 0.7 million operations. h. Circuit Breakers All circuit breakers intended to protect outputs for pumps, valves, boilers, etc. shall be suitable for the specific load required and meet the following specifications: DIN-rail mounted, life expectancy of >4000 cycles, ambient temperature of 32 to 104 F / 0 to 40 C and be CSA and UL approved. i. Main Disconnect The main panel disconnect shall be UL and/or CSA approved for use in USA and Canada. The disconnect shall use a clamp type system of wire fastening for all incoming and outgoing wire connections. The disconnect switch shall show indication of either on or off. The switch handle shall allow a key lock to prevent the panel from being turned on by others than key holder. 2. Control Functionality & Features: a. Web-based user interface allows for remote, and live, monitoring of the entire control system Override equipment behavior
Make adjustments to all setpoint calculations, schedules, reset curves and PID parameters. Review Alarms and history trends Various user levels and automatic conversion between metric and English units 10 Touch panel mounted in panel to display this interface on site b. Trending and Alarms Alarms can be created on any numeric value range or status feedback signal Alarms can be e-mailed out or collected centrally (via Supervisory station) Trends are stored internally or can be downloaded to off-site supervisory station Custom graphs can be built comparing multiple data points for any time range. c. Communication options This platform can communicate key parameters and setpoints with a 3rd party building management system via BACnet IP IP address, BACnet ID, TCP port, and description will be adjustable through web interface. d. Boiler Plant Staging and Rotation System supply setpoint will be based on the highest of either of the following: 1. Adjustable outdoor reset parameters. 2. external 0-10V setpoint signal 3. external setpoint provided through BACnet/IP 4. Demand from DHW Control communications to all boilers is done through the Viessmann LON communication protocol using the Vitogate 300 gateway 1. Each boiler control will be installed with a LON card. 2. All boilers will have one corresponding Vitogate 300 installed in the cascade panel. 3. Each lead-control will be provided with a setpoint and start/stop command via said Vitogate 300. 4. Boiler temperature, firing rate, fault status, and other key parameters will be used as feedback for the cascade panel. Staging of the boilers is based on common supply temperature vs setpoint using PID control 1. The PID parameters will be adjustable to allow the system to stage boilers at varying rates 2. The rotation sequence, and thus the lead boiler, will change based on a timer. 3. A minimum number of boilers can be required during DHW demand. 4. Staging of each boiler is controlled by the logic inside the lead module using a Vitotronic GW6C. e. [OPTIONAL] Variable speed boiler pump Control panel will assume control of powering and start/stop commands of the pumps Three adjustable speeds will be selected via 0-10V signal based on how many units in the CA3 are online. f. Space Heating
A specified quantity of space heating control circuits shall be included in the control. Control of the heating circuits shall be by means of a 3- or 4- way mixing valve and actuator. The output signal to the mixing valve actuator shall be 120 or 24 VAC, 3-point floating type. A strap-on supply sensor shall be supplied by the control manufacturer for each circuit. A output for heating circuit pump must be included. Testing of the mixing valve actuator and pump shall be possible through the control's diagnostic system. Via digital communication with the boiler control processor and mixing valve control processor, a temperature differential shall be automatically maintained. This differential shall be factory preset to 15 F / 8 C and be field adjustable. In multiple mixing valve circuit applications, the boiler supply temperature shall maintain a reset schedule based on the highest mixing valve circuit curve plus the temperature differential. g. DHW Control The control of an indirect-fired domestic hot water tank shall be based on the actual tank temperature and required set-point temperature. If the domestic hot water tank temperature drops below the required setting (+ -3.6 F / + -2 C switching differential), the boiler(s) shall be activated. The boiler temperature shall be calculated to 36 F / 20 C above the required domestic hot water set-point. The boiler control shall energize/deenergize (and if applicable modulate) the burner to maintain that setpoint automatically. The domestic hot water pump shall only be activated if there is a call for heat from the tank and the boiler temperature is 27 F / 15 C higher than the domestic hot water tank temperature. The domestic hot water pump shall be de-activated on a time delay or immediately if space heating demand is present. An output for domestic hot water re-circulating pump shall be included in the SCP. An output for domestic hot water safety aquastat shall be included in the SCP. Programmable energy-saving features shall include 7-day, 4-event per day setback programming for space heating and domestic hot water production. DHW production is controlled through start/stop of the DHW loading pump. Adjustable set temperature and dead-band Day schedule will be able to reduce setpoint temperature during off-peak hours. a. Day schedule will control DHW recirculation pump control h. High Temperature Zone Control The SCP shall include an output for a high temperature radiator pump(s). A output for optional room thermostat(s) shall be included in the SCP. i. Pump Outputs All outputs for pumps of 120/240 V, <12 FLA, 1 PH shall include ON/OFF/AUTO selector switch, pump status indication, and over-current protection. All outputs for pumps of 120/240 V, >12 FLA, 1PH; 208 V, 3 PH; 460 V, 3 PH; 575 V, 3 PH shall include ON/OFF/AUTO selector switch, pump status indication, and overload protection. 3. Installation: a. Follow manufacturer s installation instructions. Before operating the boiler/burner
unit, a qualified heating contractor shall carry out initial start-up. b. The installation must conform to the requirements of the authority having jurisdiction or, in the absence of such requirements, to the following codes (latest editions): CSA C22.1 Canadian Electrical Code and/or local electrical codes (for Canada); ANSI/NFPA 70 National Electrical Code (for U.S.A.). c. Once the installation work is complete, the heating contractor must familiarize the system operator/ultimate owner with all equipment. A licensed professional heating contractor must perform the installation, adjustment, service, and maintenance of the equipment.