Heaters Set up Direct – Indirect

Department: Tool Department 

Topic: Site Operations 

Process: Heaters Set up Direct – Indirect  

Objective 

The proper setup and safe operation of both direct-fired and indirect-fire heater units used in outdoor or large indoor workspaces, ensuring efficient and sage heating in cold environments.  

Background 

Direct-fired heaters – are efficient because they convert nearly 100% of fuel to heat.  

Indirect-fire heaters – use a heat transfer fluid to prevent direct contact with combustion gases. These are not to be used in wood frame structures. 

Things to Consider 

Direct-fire heaters  

Advantages – Highly efficient, more power in a smaller unit, portable and convenient.  

Disadvantages -Requires ventilation, require fresh air, and creates moister air. 

Indirect-fire heaters  

Advantages – Creates cleaner Air, Creates drier air. 

Disadvantages – Less portable and less convenient, less efficient, and less precise temperature control.  

Direct-Fire Heater Set Up 

• Hose and Regulator Assembly (If not already assembled) 

• Apply pipe thread compound at threaded connections and connect the components together and tighten securely.  

• Tradesman 170 Propane Gas 

• Thread swivel nut end of hose-to-hose threads on adapter (Fig 1).   

• Apply compound at 3/8-inch threads of hose adapter (Fig 1). 

• Thread hose adapter to inlet of gas control valve (Fig 1) 

• Apply compound thread rigid hose end into regulator outlet (Fig2). 

Tradesman 400 LP 

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• Apply compound and thread rigid hose end into gas inlet at heater (Fig 3) 

• Apply compound at ¼-inch threads of hose adapter and thread into regulator outlets (Fig4). 

• Thread swivel nut end of hose-to-hose threads on adapter (Fig 4). 

• Tradesman 170 Natural Gas 

• Apple pip thread compound at threaded connections and connect the components together (Fig 5). 

• When using propane as the fuel.  

• Assemble the components shown in below (Fig 6). 

• Connect POL nut and stem (Fig 7). 

• When using Natural Gas as the fuel (Do NOT use the POL fitting). 

• Ensure the natural gas supply has line pressure of minimum 2 PSIG up to a maximum 20 PSIG 

• Connect the hose to the regulator’s outlet and at the heater’s gas inlet 

• Connect the regulator to the natural gas supply using the appropriate fittings. 

• Tighten all connections securely. 

Connecting Propane Regulator to Propane Gas Supply 

• At the inlet of the regulator is a male nut and stem called a POL. 

• Remove cap from the POL 

• Insert POL stem into the valve on the propane fuel container. 

• Thread the nut counterclockwise into the container’s valve. 

• Tighten the nut securely with wrench.  

• Slowly open the tank or cylinder valve. 

• This will prevent lock-up of the excess flow valve within POL stem. 

• Check all connections for leaks 

• Do not use flame to check for leaks 

Start-Up Instructions 

• Connect the heater’s electrical cord to an approved electrical outlet. 

• Open the gas supply valve slowly. 

• For LP heaters, this is located on the tank or cylinder. 

• Set the fuel selector valve to the correct position (Fig 8)  

• Set thermostat on heater to a setting above room temperature. 

• The heater will start, and the burner will ignite. 

• Position the variable rate valve to desired heat (Fig 9) 

Shut Down Instructions 

• Close the gas supply valve. 

• Allow the heater to burn off any fuel gas remaining in the gas supply line. 

• Set the thermostat to its lowest setting. 

• Disconnect the heater from its gas and electrical supplies.  

Indirect- Fire Heater Set Up 

• Installation: 

• When transporting, use both lifting eyes located on sides of heater. 

• Place the unit on a level and non-combustible surface. 

• Minimum clearances from combustibles: 

• Outlet, minimum 10 ft 

• Sides, minimum 3 ft 

• Top, minimum 3 ft 

• Fuel Supply: 

• Ensure that for the surrounding temperature, size, and capacity of the propane supply cylinder is adequate to provide the rate BTI/HR input to the heater. 

• Visually inspect the hose assembly 

• Ensure protection of hose from high traffic areas. 

• Purge air from line and wait 10 minutes from ga to dissipate 

• Check hose any gas leaks 

• Fuel hose must be UL approved 

• Electrical: 

• Electric cable extensions must be 150V minimum to ensure proper operation.  

• Exhaust Flue Pipe: 

• The unit is to be connected to a flue pipe with adequate draft 

• This ensures proper start and operation of the unit 

• The flue pipe is to be made of non-combustible materials and clearances from combustible materials must be a minimum 8 inches (temperature of flue gases is approximately 410°F). 

• Discharge Ducting (Warm Air): 

• Minimum clearance from combustible materials is 4 inches. 

• Use steel ducting or fabric ducting capable of withstanding maximum temperature of 225℉

• Maximum length of duct: 50 ft (straight). 

• Duct Diameter: 12 inches. 

• Make sure that the duct is safely and properly fastened to the outlet. 

• Avoid sharp bends and corner to ensure maximum air flow. 

• Avoid back pressure/heat accumulation in heater. 

• To conserve heat duct piping can be wrapped with concrete blanket avoid getting to close to discharge.  

Failure to comply with these recommendations could result in a shutdown of unit. 

Start up 

• Check that the control switch on the control box is in the position “0” (STOP). 

• Pre-select desired temperature on the room thermostat. 

• The temperature must be set higher than the ambient temperature. 

• The temperature must be set higher than the ambient temperature. 

• Open all possible shut-off devices of the fuel supply lines. 

• Turn the control switch on the control box to position “1” (HEATING). 

• When the ambient temperature level is low, the burner switches on automatically. 

• The fan does not switch on until the set temperature as been reached (takes approximately 1-5 minutes). 

• After starting up: 

• The heater will operate automatically by the thermostat. 

• The thermostat and burner sensor control the running sequences of the burner and fan sensor controls the fan function. 

• Overheat limit reset controls (STB) and shuts off the heater (burner) in the case of overheating. 

• The unit can also be used for ventilation purposes only, if needed 

• Turn the control switch on the control box to position “2” (VENTILATION). 

• Unit is now in the continuous ventilating mode. 

• Heating is not possible in this mode. 

Shut Down 

• Turn control switch to position “0” (STOP). 

• Close all fuel supply. 

Important: The air supply fan continues to run to cool down the combustion chamber/heater exchanger. The fan can restart for several times before finally switching off.