Guide Specs

SERIES 79 DIRECT GAS FIRED DOOR HEATER SK-880-79 NOVEMBER, 1997

The Direct Gas Fired Door Heater shall be manufactured by Hartzell Fan, Inc.® and identified as a Series 79. The design shall be classified as a blow-through type, indoor, packaged configuration, for horizontal or vertical installation. Units shall be an assembly consisting of a fan section and a heating section. The fans section shall contain an electric motor powered, direct connected, duct axial propeller fan. 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 and monitor and regulate the combustion process. Two models shall be available providing 700,000 to 990,000 Btuh of heating capacity from 6500 to 7900 SCFM of airflow for the model DH22 and the model DH24, respectively.

The fan propeller shall be an airfoil design cast of 319 aluminum. The motor shall be a totally enclosed, air-over type supported by a steel base within the housing.

The burner shall be classified as a raw gas type, stainless steel ring burner. Main burner ignition shall be accomplished with a pilot flame activated by an interrupted ignition device. Combustion will 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, 14 gauge, hot rolled, low carbon steel sheet. The housing 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. 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 spun orifice to direct and increase exit airflow velocity. The housing shall be equipped with lifting lugs.

An electromechanical control system within a NEMA 3R control cabinet shall be furnished. The gas plumbing train and control scheme will meet FM (type 1) or IRI (type 2) requirements, as specified. Type 1 units shall have a gas valve train incorporating a secondary SSOV and a vent valve to provide a block and bleed function. Type 2 units shall have high and low gas pressure switches to prevent operation under marginal supply pressure conditions. An electrical switch, activated by the movement of the exterior door under the influence of the unit, shall initiate and terminate unit operation. A magnetic, full voltage, fan motor starter shall activate with the closure of the door switch and permit the heating system to operate. A selector switch mounted on a remote operating station shall be provided to cause the unit to cease operation, to provide airflow only, or to provide heated airflow. Airflow over the burner shall be proven before burner ignition. In the event of a condition occurring which adversely affects the combustion system, the system shall shutdown and shall not recycle automatically. Such a failure shall be indicated by light at the remote station. Remote reset shall be accomplished when the flame safeguard is not locked out, as indicated at the remote station. A manually resettable high limit temperature sensor in the housing shall prevent operation under abnormal and hazardous conditions. The heat input rate is manually adjustable and directly varies according to the inlet gas pressure to 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.