Guide Specs
SERIES 811 DIRECT GAS FIRED SHAFT HEATER SK-880-811 NOVEMBER, 1997
The Direct Gas Fired Shaft Heater shall be manufactured by Hartzell Fan, Inc.®, and identified as Series 811. The design shall be classified as a draw-through type, outdoor, mobile, packaged configuration. Units shall be a skid mounted, modular assembly consisting of a fan section, optional filter section, and a heating section. The fan section shall contain an electric motor powered, belt driven, propeller fan. The filter section shall contain a framework supporting reusable or throwaway type air filters. The heating section shall consist of an atmospheric burner for combustion of natural or propane gases; a control system to activate/deactivate the unit, monitor, and regulate the combustion process, and modulate the discharge air temperature; and an access door for service purposes. Thirty-six models shall be available providing 700,00 to 10,000,000 Btuh of heating capacity from 7000 to 100,000 SCFM of airflow, respectively, at 0 to 0.5 in. W.G. external static pressures.
The fan propeller shall be an airfoil design cast of 319 aluminum. The propeller shall be supported by a solid steel spider within an inlet orifice panel. The motor shall be an open end protected type with fittings for bearing lubrication. Pillow block ball bearings having extended grease lines shall support he propeller shaft. The motor and propeller shaft sheaves shall be interconnected via oil, heat, and static resistant belts. A combination motor cover and belt guard shall be furnished as standard.
The burner shall be classified as a commercially available, raw gas type line burner with a maximum 25:1 turndown ratio with natural gas or 20:1 with propane gas. Burner construction shall consist of a cast iron main body with stainless steel mixing plates attached. Main burner ignition shall be accomplished with a pilot flame activated by an interrupted ignition device. Combustion shall be monitored by an ultraviolet radiation sensing, flame safeguard system. Airflow speed over the burner is factory preset and is not adjustable.
The housing shall be formed of welded, heavy gauge, hot rolled, low carbon steel sheet. Construction shall be modular incorporating bolted and gasketed, reinforced flanges at joints interconnecting sections of the housing. Foreign objects shall be protected from entering the housing with a 1-1/4 inch flat wire mesh inlet guard. The housing shall be mounted on a skid formed of steel I-beams, and equipped with fixed lifting and positioning lugs and tie off points. The unit shall be protected from corrosion with a two-step process consisting of a phosphatized surface preparation followed by an application of an industrial air-dry enamel paint.
An electromechanical control system with an NEMA 4/12 control cabinet shall be furnished. The gas plumbing train and control scheme shall meet FM/IRI requirements. Automatic restart of the system after shutdown shall not be allowed. The unit shall be equipped with an outdoor air temperature sensor to regulate unit operation according to weather conditions. A discharge high air temperature sensor and a high limit mounted in the housing shall prevent operation under abnormal and hazardous conditions. Airflow over the burner shall be proven before pilot ignition marginal supply pressure conditions. A modulating regulator shall modulate the gas flow to the main burner in response to a combination discharge air temperature sensing and outdoor air temperature compensating control. Each unit shall be equipped with indicating lights on the control panel to aid in troubleshooting problems.
Fans shall be balanced in accordance with AMCA Standard 204-96, fan application category BV-3 (comparable to Grade G6.3). Fan performance shall be based on tests conducted in HartzellÕs AMCA accredited test laboratory in accordance with AMCA Standard 210 for air and AMCA Standard 300 for sound performance.
