SNOW MELTING SYSTEM SPECIFICATION
PART 1 - GENERAL
1.01 WORK INCLUDED
A. Design, furnish and install a complete hydronic snow melting system including piping, manifolds, control system and heat transfer package in accordance with this specification. System shall be furnished by a single manufacturer regularly engaged in the design and manufacturing of snow melting systems. System designed by local representative is not acceptable.
B. Manufacturer shall provide inspection and technical assistance during pipe system start up.
1.02 SYSTEM DESCRIPTION
A. System shall be a hydronic type consisting of heat exchanger (or boiler), circulating pump, air separator, expansion tank, piping and control system. The system shall be designed for a performance capability of Select: 150, 200, 250, 300, or 400 steps only BTUH per square foot, 130º F maximum glycol temperature at 22.4º F fluid temperature differential. Heat transfer package and control system shall be factory pre-assembled and tested unit by Snow Technologies, Inc.
B. System designed and sized to provide snow melting by continuously operating the system in idle mode is not acceptable.
PART 2 - PRODUCTS
2.01 ACCEPTABLE MANUFACTURER
A. The system shall be as manufactured by Snow Technologies, Inc., Livonia, Michigan, 1-800-683-MELT or prior approved equal.
A. Heating circuits and underground supply and return piping shall be flexible polyethylene homopolymer with Plastic Pipe institute approved hydrostatic stress rating for use at 140º F. Pipe shall conform to ASTM D-746, D1248, D1525, D2239, D2837, D3350, D1505, D1238, D638, D1693, D790 standards, including low temperature rating exceeding -100º F. PEX piping conforming to ASTM F876, 877 as manufactured to Silane method is also acceptable.
B. Radial distribution manifolds and fittings shall be all brass or copper as manufactured by Snow Technologies, Inc. Radial distribution manifolds shall provide balanced flow in each heating circuit without balance valves or reverse return assembly. In-line or log style manifolds are acceptable if provided with individual circuit balance valves.
C. Clamp band, housing and screw shall be all 300 series stainless steel. The use of compression fittings for PEX piping is acceptable. Spring clamps or crimp rings are not allowed.
D. Access covers shall be cast in place reinforced concrete over all pipe connections, fittings and manifolds. Tapered forms for covers shall be as manufactured by Snow Technologies, Inc. Forms shall be vacuum molded from ABS, and shall not have to be removed to cast the concrete cover. Manifolds installed below structural concrete shall be serviceable from below without an access cover.
E. Balance valves, service valves and plastic to metal pipe adapters shall be manufacturer's standard suitable for specified operating conditions. Balance valves shall be equipped with a handle, which indicates flow setting, a memory stop, and ports for flow and temperature measurement. Balance valves shall also be capable of adding a drain valve while system is under pressure.
A. HEAT TRANSFER PACKAGE
1. The unit shall consist of heat exchanger (or boiler), in-line pump(s), air separator, expansion tank, service valves, triple duty valve, thermometers, pressure gauges and pre-wired digital control system. The unit shall be factory pre-assembled on a structural steel frame, piped, painted and wired. The package shall be hydrostatically tested prior to shipment. Heat transfer package designed or assembled by local representative or contractor is not acceptable.
2. Heat exchanger (or boiler) shall be sized for the design output using inhibited ethylene glycol and water solution (50/50), Dowtherm SR-1, or propylene glycol, Dowfrost-HD, substitution is not allowed.
3. Heat source shall be (Select one: ____ volt electric, natural or propane gas, heating oil, hot water ____ºF supply, or steam ____ psig.
4. The pump shall be in-line type, sized as required and shall be suitable for ____ volts, ____ phase, 60 hz service.
5. Glycol shut off valves, service valves, fill valve, air purge valve and relief valve shall be manufacturer's stand suitable for use as required.
6. Pressure gauges and dial thermometers shall be manufacturer's standard.
7. Air separator, expansion tank and fittings with liquid level indicator and level switch shall be manufacturer's standard.
8. Package piping 4" and under shall be type L copper. Piping over 4" shall be schedule 40 black steel with welded or grooved connections at manufacturer's option.
9. Package steam and condensate lines shall be factory pre-piped and shall include a 2-way modulating steam control valve, strainer, steam trap, and gate valve (Steam only).
10. Package hot water supply and return lines shall be factory pre-piped and shall include a 3-way modulating hot water control valve, bypass piping and a balance valve (Hot water only).
B. CONTROL SYSTEM
1. Control system shall consist of a fused disconnect switch, fuses, starter(s), 24 vac control circuit transformer, digital controller all housed in a single UL listed NEMA 4X control cabinet.
2. Starter(s) shall be I.E.C. type with overload relay(s) suitable for use at ____ volts, ____ phase, 60 hz and shall be factory wired to pump motor(s) and control system. Starter(s) shall be manufacturer's standard. A fused disconnect switch shall be provided with a door interlock to prevent opening electrical enclosure while system is energized.
3. Digital electronic temperature control system shall be factory wired and programmed and include: programmable digital controller, 24 vac control circuit transformer with fused primary and secondary, glycol temperature sensor, replaceable concrete temperature sensor, outdoor air temperature sensor with sun shield, glycol manual reset high limit with fault indicator light, expansion tank level switch, pump discharge pressure switch, cycle initiation push button switch, system "ON" pilot light and Hand-Auto selector switch. Terminal blocks shall be provided for all external sensors and shall be clearly labeled as to their use. An "as-built" electrical diagram shall be permanently affixed to the interior of the control cabinet.
Systems furnished with backup pump shall automatically start the backup pump on primary pump failure and shall include a 3-position pump service / lock out switch.
4. Mast mounted automatic snow and ice detection system shall include outdoor temperature sensor, moisture sensor and heater. Sensor shall be wired to control panel by installing contractor as directed by manufacturer.
5. System operation shall be initiated by the automatic snow and ice detector if ambient temperature is below 34º F and moisture is present on the sensor. Once activated, the system shall monitor glycol and surface temperatures and modulate the control valve (or boiler) to maintain the surface temperature at set point. The glycol temperature shall be limited to a maximum of 130º F with a 22º F maximum temperature differential and be designed to prevent thermal shock. System will deactivate 1 hour after snow or ice signal ends. In automatic mode, the system may also be activated by pressing the "cycle" switch. The system will activate for 5 hours. At the completion of the time cycle, the system will reset in automatic mode. System operation shall also be able to be initialized in automatic by remote contact closure. The system shall reset in automatic at the end of the cycle.
6. System status outputs shall be provided for remote monitoring of the following: freeze warning alarm, general system alarm, glycol temperature, surface temperature and outdoor air temperature. Remote temperature outputs shall be 4-20 ma.
7. Modem and service contract for remote monitoring of system by the manufacturer shall be optionally available. The controller shall be capable of being upgraded to Bacnet or Lonworks compatability.
PART 3 - EXECUTION
3.01 TECHNICAL SERVICE
A. Submittal and installation drawings shall be as prepared by Snow Technologies, Inc. and shall include: ⅛" scale layout of supply and return mains, ¼" scale heating circuits layout, system piping schematic, heat transfer package, electrical diagram, operating sequence, section cuts, details and shall be available electronically. Waterproof color plots of heating circuit layout shall also be provided to simplify installation. Operating and maintenance manuals shall be provided at the completion of the installation along with a copy of submittal data on CD.
B. Inspection and technical service shall be provided by Snow Technologies, Inc. prior to concrete cover of piping system and before starting the heat transfer package. Owner traning shall be provided as part of system start up inspection. All inspections shall be performed by factory technicians. Inspection by local representative is not acceptable.
A. PIPING SYSTEM
1. Supply and return mains buried below grade shall be polyethylene as provided by Snow Technologies, Inc. and shall be set in sand below concrete. Supply and return mains shall be balanced by reverse return where applicable. Supply and return mains below structural concrete shall be type L copper or schedule 40 black, insulated, steel.
2. Heating circuits shall be attached to reinforcing steel with nylon ties as provided by the manufacturer. Steel tie wire is not acceptable. Heating circuits shall be installed as specified center-to-center spacing with 12-inch minimum diameter bends and shall be continuous without splices or fittings from supply to return manifold. Heating circuits shall be embedded in concrete 2" below finished surface. No piping may extend through expansion, construction or working joints.
3. Reinforcing steel shall be furnished by the project contractor and supported as required in heated area. Reinforcing steel shall be #10x6x6 W.W.F. minimum.
4. Distribution manifolds and all pipe connections shall be easily serviced through removable cast in place concrete covers. All fittings shall be kept free of concrete. Manifolds installed below structural concrete shall be serviceable from below without access cover.
5. The piping system shall be tested according to the manufacturer's recommendations, but for not less than 48 hours at 80 psi. The use of water for testing is not acceptable.
B. HEAT TRANSFER PACKAGE
1. Pre-assembled Heat Transfer Package shall be set in place by the project contractor.
2. Power wiring, remote sensor wiring and the required quantity of inhibited ethylene glycol (Dowtherm SR-1) or propylene glycol (Dowfrost HD) substitution is not allowed, shall be furnished by the project contractor.
3. Supply and return mains above grade or inside building shall be type L copper or schedule 40 black steel pipe, insulated, furnished and installed by the project contractor.
4. Zone flow balancing shall be performed by the project contractor. Balance valves shall be equipped with flow setting indicator, memory stop lock to prevent accidental adjustment. Flow rates and settings for balance valves shall be provided by Snow Technologies, Inc.
1. At the completion of installation, as described herein, and in the manufacturer's installation manual, the manufacturer shall furnish Certificates of Inspection to the project contractor. Limited warranty period shall commence on factory system start up and shall consist of five (5) years on the exterior piping system, clamps, manifolds and adapters and two (2) years on the heat transfer package and control system. Limited warranty shall be provided to the owner through the project contractor.
© 2003 Snow Technologies, Inc.