SECTION 15863
FUEL FIRED UNIT HEATERS
PART 1 - GENERAL
1.1 SECTION INCLUDES
A. Natural Gas fired, separated combustion unit heaters - propeller fan type.
1.2 REFERENCES
A. American Gas Association (AGA)
B. American National Standards Institute (ANSI):
1. ANSI Z223.1 (NFPA 54) National Fuel Gas Code
2. ANSI/ASHRAE 103 Heating Seasonal Efficiency of Central Furnaces and Boilers, Method of Testing
3. ANSI/NFPA 211 Chimneys, Fireplaces, Vents and Solid Fuel Burning Appliances.
1.3 SUBMITTALS
A. Submit shop drawings in accordance with the General Conditions and Division1.
PART 2 - PRODUCTS
2.1 GAS FIRED SEPARATED COMBUSTION UNIT HEATERS - PROPELLER FAN TYPE
A. General: Install gas fired propeller unit heaters as indicated on schedules. Performance shall be as indicated on the equipment schedule in the plans. Unit heaters shall have American Gas Association design certification. Unit Capacity: The unit input capacity shall be as listed on the plans. The output capacity shall be a minimum of 80% of the input based on steady-state thermal efficiency as certified by the American Gas Association.
B. Heat Exchanger: The heater shall be equipped with either a multi-cell, 4-pass serpentine style steel heat exchanger, a 18 gauge aluminized steel tubes and headers if a Modine unit, or a 409 Stainless Steel heat exchanger as indicated on the gas fired unit heater schedule.
C. Burner: The units shall incorporate a single, one-piece burner assembly with a single or multiple orifice. The burner shall have a continuous wound close pressed stainless steel ribbon separating the flame from the burner interior. All units shall have a single venturi tube and single or multiple orifice supplying fuel to a one-piece burner housing. Each heat exchanger cell shall use balanced draft induction to maintain optimum flame control.
D. Controls:
1. Controls shall include a single stage gas valve; direct spark multi-try ignition with electronic flame supervision with 100% lockout integrally controlled via a printed circuit control board. The control board shall also incorporate diagnostic lights, DIP switches for fan overrun settings, and a relay for fan only operation. All units shall be equipped with a safety limit switch.
2. All controls shall be enclosed in the sealed control compartment to protect them from accidental damage, dust, and atmospheric corrosion.
E. Combustion Air and Venting:
1. The unit shall have a factory-installed power venter device to draw combustion air from outside of the building. The outside air shall enter the unit through a factory- installed round inlet air terminal on the rear of the heater. The control compartment shall be sealed and the access door shall be gasketed to prevent dirt, lint, dust, or other contaminants present in the heated space from entering the unit. The control compartment door shall be equipped with a safety interlock switch to prevent operation when the door is open.
2. The combustion air supply pipe and flue exhaust pipe shall be run in parallel from the heater to a factory supplied concentric adapter assembly, which allows for a single wall or roof penetration, to the horizontal air inlet and vent terminal.
3. The combustion air/venting system shall include a vibration isolated power venter motor and wheel assembly and a combustion air pressure switch. Unit shall include a flame rollout switch
F. Electrical:
1. Operation shall be controlled by an integrated circuit board that includes LED diagnostic indicator lights. Supply voltage connections shall be made in a sealed junction box. 24-volt control connections shall be made on an externally mounted terminal strip with connections (W1, W2, R, and G). All form RZ-NA C-UDAP/S, Page 8 internal wiring, both line and control voltages, shall be terminated by insulated terminal connectors to minimize shock hazard during service.
2. Each unit shall be equipped for use with (115/1) voltages as scheduled as plans.
3. All units will be equipped with a built-in disconnect switch.
G. Cabinet
1. The cabinet shall be low profile with a pre-coat or powdercoat RAL 1001 white paint finish. Finish shall be a minimum 80 gloss on G30 galvanized steel. The cabinet shall be constructed so that screws are not visible from the bottom, front, or sides, except for service panel and accessories. Unit construction shall incorporate a beveled front corner on control side for additional cabinet rigidity. All units shall be manufactured with a tooled drawn supply air orifice on the rear panel to reduce fan inlet noise.
2. The unit shall be designed for ceiling suspension featuring 3/8 inch female threads (hanger kits for 1 inch pipe) at both 2-point and 4-point locations with no additional adapter kits.
3. The cabinet shall be equipped with painted, roll-formed horizontal louvers. Louvers shall be spring held and adjustable for directing airflow.
4. The cabinet shall be equipped with a full safety fan guard with no more than ½ inch grill spacing on sizes 30-125 or no more than 1 inch on sizes 150-400. The enclosed motor and fan assembly shall be resiliently mounted to the cabinet to reduce vibration and noise.
5. The unit shall be designed with a full opening service access panel complete with screw closure attachment and lifting handle for removal. Service panel shall be fully gasketed and equipped with a safety interlock switch. All components in the gas train, all standard electrical controls, and the power venter shall be within the sealed service compartment.
6. Minimum top clearance from combustibles shall be 1 inch for sizes 30-125 and 4 inches for sizes 150-400. Minimum bottom clearance from combustibles shall be 1 inch for all sizes. Minimum clearance from combustibles on non-service side shall be 1 inch for sizes 30-125 and 2 inches for sizes 150-400.
H. Low voltage room thermostat to be provided under Specification Section 15971.
I. Available Manufacturer: Modine, or Sterling.
PART 3 - EXECUTION
3.1 EXAMINATION
A. Verify that space is ready for installation of units and openings are as indicated on shop drawings.
B. Verify that proper power supply is available.
C. Verify that proper fuel supply is available for connection.
3.2 INSTALLATION
A. Install in accordance with manufacturer's instructions.
B. Installed condensate drip leg with drain port on all vents. Drip leg to be sealed water tight. Install CPVC trap and drain line to drain port. Route to nearest drain or out thru wall to rade. Coordinate with engineer.
C. Install to NFPA 90A.
D. Install gas-fired units to ANSI Z223.1 (NFPA 54).
E. Provide vent connections to ANSI/NFPA 211.
F. Install unit heaters with vibration isolation.
G. Startup units in accordance with manufacturer’s instructions.
1. Measure, adjust and set manifold gas pressure to factory recommendations utilizing a manometer to properly read pressures. Adjust anticipator on room thermostats serving unit heaters to factory recommendations for type and model. If condensate dripping occurs from vent pipe, install additional insulation on vent/combination box.
END OF SECTION
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