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This heater is not intended for use in hazardous atmospheres where flammable vapors, gases, liquids or other combustible atmospheres are present as defined in the National Electrical Code. Failure to comply can result in personal injury or property damage The NWHO(F)-18 series is a general purpose regular and fuel oil solution circulation heater intended for use indoors. The steel-sheathed tubular elements are centered in a steel heating chamber and sealed into a removable steel flange. The assembly is surrounded by insulation and a sheet metal jacket. Depending upon the order specifications, the NWHO(F)-18 may or may not be factory equipped with an AR or other Chromalox thermostat. Such thermostats function to control outlet temperatures and to limit internal temperatures under abnormal flow conditions. These controls do not fail-safe. The system designer is responsible for the safety of this equipment and should install adequate back-up controls and safety devices with their electric heating equipment. Where the consequences of failure could result in personal injury or property damage, back-up controls are essential. © 2010 Chromalox, Inc. INSTALLATION ELECTRIC SHOCK HAZARD. Disconnect all power before installing or servicing heater. Failure to do so could result in personal injury or property damage. Heater must be installed by a qualified person in accordance with the National Electrical Code, NFPA 70. 1. Vertical Mounting (Preferred) When the heater is vertically mounted, the terminal housing will be at the top of the heater. The inlet pipe will be located on the side near the bottom of the heater and the outlet pipe at the top. The axis of the chamber will be in a vertical position as in the photo on previous page and as in Figure A. Note: A drain pipe located at the bottom of the heater should be provided and enough room left, when mounting heater, to allow draining the heater. 2. Horizontal Mounting (Optional) CAUTION: When mounting heater horizontally, inlet and outlet pipes must be up. In any other position, heater cannot be purged of air, and elements may be seriously damaged. (See Figure B) 3. Whether vertically or horizontally, the heater should be rigidly mounted so that vibration is at a minimum since excessive vibration will result in erratic thermostat operation. The NWHO(F)-18 is provided with mounting lugs to support the heating chamber. (See photo) Incorrect Correct Figure A — Vertical Mounting 4. By using a slotted mounting assembly on either of the lugs, the heater chamber will be permitted to expand with increasing temperature. 5. Provide adequate space at terminal to end permit withdrawal of the heater from chamber should servicing be required. FIRE HAZARD. Since heaters are capable of developing high temperatures, extreme care should be taken to: A. Provide a minimum of 6” spacing from chamber and related piping to nearest combustible material. B. Do not operate near combustible fluids or vapors. FREEZE HAZARD. This unit is equipped with a thermowell for process control or over-temperature control. Do not allow moisture to accumulate in thermowell. Freezing temperatures can cause damage that may result in the heated medium leaking into terminal enclosure. Correct Incorrect Figure B — Horizontal Mounting WIRING 3. Power controllers must be used when heaters are rated for 480 volt service or if the amperage rating of the heaters exceeds the contact rating of the thermostat. ELECTRIC SHOCK HAZARD. Any installation involv 4. Refer to Wiring Diagram Table B for the proper wiring diagram ing electric heaters must be performed by a quali for connecting heater. fied person and must be effectively grounded in accordance with the National Electrical Code to Wiring Diagrams – Table B eliminate shock hazard. 1. Be sure line voltage matches heater voltage as shown on nameplate. 2. Electric wiring to heater must be installed in accordance with local and National Electrical Codes by a qualified person as defined in the NEC. 240V 3–3O 480V 3–3O Model Fig. Fig. Any Heater 1 2 L1L2L3ContactorContactorContactorThermostat120-v OR240-vFigure 1 – 240V 3-3 o . 120-v OR240-vFigure 2 – 480V 3-3 o .L1L2L3ContactorContactorContactorThermostat Note: Dotted lines indicate “customer furnished.” However, thermostat may be furnished by Chromalox if so specified on the order. OPERATION FIRE/EXPLOSION HAZARD. Do not exceed the Pressure-Temperature rating of the flange as listed in ANSI B16.5. IMPORTANT: It is the responsibility of the purchaser of the heater to make the ultimate choice of sheath material based upon his knowledge of the chemical composition of the corrosive solution, character of the materials entering the solution, and controls which he maintains on the process. Sheath corrosion can result in a ground fault which, depending upon the solution being heated, can cause an explosion or fire. 1. Do not heat solutions that are corrosive to the heating element sheath or the heating chamber. 2. Terminal end...