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manual abstract
Failure to comply can result in explosion or fire. Hazardous area terminal housings are available, consult your Local Chromalox representative for details. The NWHMT series is a general-purpose water circulation heater intended for use indoors. The three Copper sheathed tubular elements are centered in a 21/ 2” diameter galvanized heating chamber and sealed in a removable screwplug. The assembly is surrounded by 1-1/2” insulation and sheet metal jacket. Depending upon the specifications, the NWHMT may or may not be factory equipped with AR or other Chromalox thermostats. Such thermostats function to control outlet temperatures and limits internal temperatures under abnormal flow conditions. These controls do not fail-safe. CAUTION: Users should install adequate back-up controls and safety devices with their electric heating equipment. Where the consequences of failure may be severe, back-up controls are essential. Although the safety of the installation is the responsibility of the user, Chromalox will be glad to make equipment recommendations. INSTALLATION WARNING: Hazard of Shock. Disconnect all power before installing heater. 1. Vertical mounting (axis of chamber vertical, see above drawing.) is preferred with terminal housing at top of heater (Figure 1). 2. 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 (Figure 2). 3. The NWHMT series of circulation heaters are provided with mounting lugs to support the heater chamber. Refer to drawing above for location of these mounting lugs. 4. Mount heaters to permit unrestrained expansion of chamber due to temperature. This can be accomplished by using a slotted mounting assembly on either of the lugs. Incorrect Correct Figure 1 — Vertical Mounting Correct Incorrect Figure 2 — Horizontal Mounting © 2010 Chromalox, Inc. INSTALLATION 5. DANGER: Hazard of Fire. Provide minimum of 6” spacing 7. If two or more heaters are needed to provide the needed heating from a chamber and related piping to nearest combustible materi-capacity, arrange them for series water flow. al. Avoid operation of heater near combustible fluids or in com-8. DANGER: Possible Explosion. A pressure relief valve bustible vapor or gas laden atmosphere. should be provided by customer at outlet of vessel. There should 6. Provide adequate space at terminal end to permit withdrawal of the be no other valving between vessel and valve. heater from chamber should servicing be required. WIRING WARNING: Hazard of Shock. Any installation involving 3. Electrical wiring to heater should be connected in rigid conduit or electric heaters must be effectively grounded in in flexible hose to keep corrosive vapors and liquids out of the teraccordance with the National Electrical Code to elim-minal housing. If high humidity is encountered, the conduit should inate shock hazard. slope down away from the heater. 4. If flexible cord is employed, a watertight connector should be used 1. Electrical wiring to heater must be installed in accordance with the for entry of the cord into the terminal housing. Outdoor applica- National Electrical Code and/or local electrical codes by a quali tions require liquid-tight conduit and connectors. fied person as defined in the NEC. 5. Bring the power line wires through the opening in the terminal 2. When element wattages are not equal, heaters must not be con- housing. Connect line wire as shown in Figures 3 through 5. nected in series. Figure 3 Figure 4 Figure 5 For 1-Phase WYE Heaters For 1-Phase Heaters For 3-Phase Delta Heaters NOTE: Dotted lines indicate “customer furnished.” OPERATION 1. Do not heat materials that are corrosive to the heating element terminal housings are available to protect heater. Check with Local sheath or chamber. For water heating service, condensate drain Chromalox Sales representative. may be provided from bottom of chamber. Check factory. 3. If foreign material is carried by the gaseous flow, install suitable 2. Terminal ends of heater must be protected from drippings, con-filters in the inlet pipe to the heater. densation spray or direct spill-over of material whose presence at 4. Do not allow heater to operate when fluid flow is interrupted. the terminals may damage heater electrical insulation. Liquid-tight MAINTENANCE WARNING: Hazard of Shock. Disconnect all power 2. Periodically check temperature control and limit control operation before servicing heater. to insure accurate and safe process operation. 3. Check all electrical connections periodically and retighten connec1. Remove heating element assembly periodically to check heater tions which may have loosened in service. Replace wire terminals sheath for corrosion or excessive oxidation. Correct operating con- which show signs of oxidation which would interfere with estab ditions to minimize sheath deterioration. lishment of reliable electrical connections. RENEWAL PARTS IDENTIFICATIO...