Guide Specs

SERIES 78H ECONO TYPE, HORIZONTAL DIRECT GAS FIRED MAKE-UP AIR HEATER SK-880-78H NOVEMBER, 1997

The Econo Type, Horizontal Direct Gas Fired Make-Up Air Heater shall be manufactured by Hartzell Fan, Inc.® and identified as a Series 78H. The design shall be classified as a blow-through type, indoor or outdoor packaged configuration. Units shall be a modular assembly consisting of fan section, optional filter section, and a heating section. The fan section shall contain an electric motor powered, direct connected, 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 and 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. Six models shall be available providing 950,000 to 2,900,000 Btuh of heating capacity from 8150 to 27,300 SCFM of airflow, respectively, at 0 to 0.25 in. W.G. external static pressures.

The fan propeller shall be an airfoil design cast of 319 aluminum. The propeller shall be mounted within a duct housing. The motor shall be an open end protected type.

The burner shall be classified as a raw gas type, stainless steel ring burner with a minimum 7:1 turndown ratio with natural or propane gases. Main burner ignition shall be accomplished with a pilot flame activated by an interrupted ignition device. Combustion shall be monitored by a flame safeguard system. Airflow speed over the burner is not adjustable.

The housing shall be formed of welded, heavy gauge, galvannealed steel. Construction shall be modular incorporating bolted and gasketed, reinforced flanges at joints joining sections of the housing. The housing shall be protected from corrosion by an application of an industrial air-dry enamel paint. Entrance of foreign objects into the housing shall be prevented with a concentric wire ring inlet guard. The discharge end of the housing shall be equipped with a motorized shutter.

A control system with a 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. In the event of flameout, fan operation shall cease and the shutter shall close. The unit shall be equipped with temperature sensors 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. High and low gas pressure switches shall prevent operation under marginal supply pressure conditions. A modulating regulator shall modulate the gas flow to the main burner in response to a combination discharge air temperature and outdoor air temperature compensating control. A magnetic, full voltage, fan motor starter shall be included. Each unit shall be equipped with indicating lights on the control panel to aid in troubleshooting problems. A remote operating station with indicating lights shall be included with the unit.

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.