SECTION 15767
ELECTRIC HEATERS
Part 1 GENERAL
1.1 SUMMARY
A. Section includes:
1. Unit heaters.
2. Cabinet unit heater.
3. Wall heaters.
B. Related Documents:
1. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division1 Specification Sections, apply to this Section.
1.2 SUBMITTALS
A. Product Data:
1. Submit “Letter of Conformance” in accordance with Section 01330 indicating specified items selected for use in project.
B. General: Submit each item in this Article according to the Conditions of the Contract and Division1 Specification Sections.
C. Product data for each type of product specified.
D. Wiring diagrams detailing power and control wiring and differentiating clearly between manufacturer-installed wiring and field-installed wiring.
E. Samples of cabinet finish colors for approval.
F. Qualification data for firms and persons specified in the "Quality Assurance" Article to demonstrate their capabilities and experience. Include lists of completed projects with project names and addresses, names and addresses of Owner’s Representatives and owners, and other information specified.
G. Field test reports from a qualified independent inspecting and testing agency indicating and interpreting test results relative to compliance with performance requirements of unit heaters.
1.3 QUALITY ASSURANCE
A. Manufacturer Qualifications: Firm experienced in manufacturing unit heaters similar to those indicated for this Project and that have a record of successful in-service performance.
B. Comply with NFPA70 for components and installation.
C. Listing and Labeling: Provide products specified in this Section that are listed and labeled.
1. The Terms "Listed" and "Labeled": As defined in the National Electrical Code, Article 100.
Part 2 PRODUCTS
2.1 MANUFACTURERS
A. Preferred Program Manufacturers:
1. Marley Electric Heating Company, Qmark Division.
B. Alternative Manufacturers: Subject to compliance with requirements, provide unit heaters by one of the following:
1. Brasch Manufacturing Co., Inc.
2. Emerson Electric Co.; Wiegand Division
3. Dunham-Bush, Inc.
4. Markel Products Company
2.2 ELECTRICAL UNIT HEATERS
A. Heating Elements: Nickel-chromium heating wire element; free from expansion noise and 60-Hz hum; embedded in magnesium oxide, insulating refractory; and sealed in high-mass steel or corrosion-resistant metallic sheath with fins no closer than 0.16 inch (4 mm). Element ends are enclosed in terminal box. Fin surface temperature does not exceed 550 deg F (288 deg C) at any point during normal operation.
B. Heater Circuit Protection: One-time fuses in terminal box for overcurrent protection and limit controls for over temperature protection of heaters.
C. Fan and Motor: Direct-drive propeller fan and manufacturer's standard motor. Motors sized 1 hp and less include motor overload protection.
D. Wiring Terminations: Match conductor materials and sizes indicated.
E. Discharge Configuration: Horizontal discharge with horizontal, adjustable louvers.
F. Discharge Configuration: Vertical discharge with radial louver diffuser.
G. Optional Accessories: Include the following:
1. Timer switch.
2. Wall thermostat.
3. Safety-switch disconnect on cover of terminal box.
4. Mercury contactors.
5. Fan-delay relay.
2.3 ELECTRICAL CABINET UNIT HEATERS
A. Description: Surface-mounting cabinet with front grille air inlet and front air outlet.
B. Description: Surface-mounting cabinet with front grille air inlet and top air outlet.
C. Description: Surface-mounting cabinet with bottom air inlet and front air outlet.
D. Description: Surface-mounting cabinet with bottom air inlet and top air outlet.
E. Description: Semirecessed, wall-mounting cabinet with front grille air inlet and front air outlet.
F. Description: Semirecessed, ceiling-mounting cabinet.
G. Heating Elements: Nickel-chromium heating wire element; free from expansion noise and 60-Hz hum; embedded in magnesium oxide, insulating refractory; and sealed in high-mass steel or corrosion-resistant metallic sheath with fins no closer than 0.16 inch (4 mm). Element ends are enclosed in terminal box. Fin surface temperature does not exceed 550 deg F (288 deg C) at any point during normal operation.
H. Heater Circuit Protection: One-time fuses in terminal box for overcurrent protection and limit controls for overtemperature protection of heaters.
I. Fan and Motor: Centrifugal blower, direct driven by a single-phase, 2-speed electric motor with inherent overload protection and resilient motor/fan mount.
J. Wiring Terminations: Match conductor materials and sizes indicated.
K. Filter: Manufacturer's standard throwaway filter, 1 inch (25 mm) thick, on inlet of each fan.
L. Filter: Manufacturer's standard washable filter, 1 inch (25 mm) thick, on inlet of each fan.
M. Unit Controls: Thermostat, fan-speed switch, fan ON-AUTOMATIC switch, night-setback relay, interval timer, and outside air-damper control switch.
N. Optional Accessories: Include the following:
1. Timer switch.
2. Wall thermostat.
3. Outside air damper and duct collar, adjustable to 50 percent outside air.
4. Disconnect switch.
5. Mercury contactor.
6. Fan-delay relay.
7. Kickplate base for floor-mounted units.
O. Finish cabinet with manufacturer's standard enamel, color as selected by Owner’s Representative.
2.4 ELECTRIC WALL HEATERS
A. Supply and install heavy-duty, wall-mounted forced-air electric unit heaters of the wattage, voltage and phase as indicated on Drawings. Design heater to provide even distribution of heated air to space by drawing return air in periphery of heater across element which shall then be discharged from center section of heater by means of an electric moor and axial flow fan blade. Heaters shall be semi-recessed type to extend no more than 2-1/2" from finished wall.
B. Heater front shall withstand less than 1/16" permanent distortion with 10.8 ft. lbs. (324 pounds) impact and 400 lbs. static force applied to 8 sq. in. area at center grille location. Construct combination return and supply grille assembly of 1/16" x 3/8" rounded edge horizontal steel louvers spaced for maximum opening of 1/4". Weld louvers at every intersection to three evenly spaced 1/16" diameter vertical members and completely framed in heavy gage anodized aluminum extrusion. Attach front assembly to chassis by hidden tamper-resistant (Allen-head) machine screws. Other parts shall be 16 gage steel zinc coated both sides finished in high gloss bronze colored baked enamel.
C. Motor shall be permanently lubricated unit bearing, totally enclosed, shaded pole type with impedance protection. Motors shall operate at no more than 1400 RPM and shall be the same voltage as the heater. A protective shield shall surround motor to separate return air from heated air.
D. Heaters shall have a rating as shown in Drawing Schedule with maximum temperature rise of 73°F.
E. Element assemblies shall consist of two or three corrosion resistant steel sheathed type elements mechanically bonded to common corrosion resistant steel fins. Each sheathed element shall consist of helically coiled nickel chromium alloy resistant wire completely embedded in a surrounded by magnesium oxide, enclosed and swedged into corrosion resistant steel sheaths. Elements shall have 2" cold conductor pins extending into the sheath and shall have a density of no more than 60 watts per inch.
F. Heaters shall be equipped with a "zero voltage reset" thermal overload which disconnects elements and motor in the event normal operating temperatures are exceeded. For safety, if opened due to abnormal temperatures, thermal overload shall remain open until manually reset by turning heater off for five minutes. Automatic reset thermal overloads which allow the element to continue to cycle under abnormal conditions will not be accepted.
G. Heaters shall be Underwriters' Laboratories listed. Heaters shall conform to Underwriters' Laboratories, Inc. standard 1025, paragraphs 31.20, 31.21, 31.22 and 31.23, and shall not be required to have "CAUTION" marking on front of heater. Heaters not conforming to these paragraphs will not be acceptable.
H. Heaters shall be controlled by integrally mounted thermostats. Thermostats shall be heavy duty, hydraulic type with a range of 40°F to 80°F and with remote sensing bulb placed in return air. Thermostats shall be electrically rated at least 125% of heater rating. Thermostats shall also act as a disconnect by breaking ungrounded conductors in OFF position. Thermostat control knob shall be covered by a 16 gage tamper-proof access plate to prevent adjustment by unauthorized personnel.
Part 3 EXECUTION
3.1 EXAMINATION
A. Examine substrates and supports to receive unit heaters for compliance with requirements for installation tolerances and other conditions affecting performance of units. Do not proceed with installation until unsatisfactory conditions have been corrected.
3.2 INSTALLATION
A. Install unit heaters as indicated, according to manufacturer's written instructions and NFPA90A.
B. Connect unit heaters and components to wiring systems and to ground as indicated and instructed by manufacturer. Tighten connectors and terminals, including screws and bolts, according to equipment manufacturer's published torque-tightening values for equipment connectors. Where manufacturer's torquing requirements are not indicated, tighten connectors and terminals according to tightening requirements specified in UL486A.
3.3 FIELD QUALITY CONTROL
A. Testing: After installing unit heaters and after electrical circuitry has been energized, demonstrate product capability and compliance with requirements.
B. Remove and replace malfunctioning units with new units and retest.
3.4 CLEANING
A. Replace filters in each cabinet unit heater.
END OF SECTION
15767 - 5 LK 00000