Chromalox NWHO-33015 User Manual

Chromalox

®

DIVISION 4 SECTION

NHWO

SALES

REFERENCE

DATE

SERVICE REFERENCE

Installation

and

RENEWAL PARTS IDENTIFICATION

PE406-5

FEBRUARY, 1999

(Supersedes PE406-4)

161-048710-001

GENERAL

INSTALLATION

© 2010 Chromalox, Inc.

Type NWHO-3 Series Circulation Heaters

(for Regular and Fuel Oil Heating)

WARNING: This heater is not intended for use in haz-

ardous 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 explosion or fire.

The NWHO-3 series is a general-purpose regular and fuel oil solu­tion circulation heater intended for use indoors. It is designed for 150
psig at 550˚F per ANSI standards.

The 3 steel-sheathed tubular elements are centered in a 3” diame­ter steel heating chamber and welded to a removable steel flange. The
assembly is surrounded by 1-1/2” insulation and sheet metal jacket.

Depending upon the order specifications, the NWHO-3 may or
may not be factory equipped with 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.

CAUTION: Users should install adequate back-up controls
and safety devices with their electric heating equipment.
Where the consequences of failure may be severe, back­up controls are essential. Although the safety of installa­tion is the responsibility of the user, Chromalox will be
glad to make equipment recommendations.

WARNING: Hazard of Shock. Disconnect all power
before installing heater.

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 above 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) —

When mounting heater horizontally, inlet and outlet pipes must be

up. In any other position, heater cannot be purged of air, and ele-

ments may be seriously damaged. (See Figure B.)

Specifications — Table A

Incorrect

Correct

Figure A — Vertical Mounting

Figure B — Horizontal Mounting

Correct

Incorrect

Regular Oil Heaters

Dimensions (In.)

Model Volts Phase kW W/In

2

ABC

NWHO-33015 3 32-15/16 22-1/2 16-1/2
NWHO-34515 4.5 32-15/16 22-1/2 16-1/2
NWHO-36015 240 or 480 1 or 3 ss 6 23 42-15/16 32-1/2 26-1/2
NWHO-37515 7.5 55-7/16 45 39
NWHO-39015 9 55-7/16 45 39

NWHO-30315 3 32-15/16 22-1/2 16-1/2
NWHO-30415 240 or 480 1 or 3 ss 4 15 42-15/16 32-1/2 26-1/2
NWHO-30615 6 55-7/16 45 39

Fuel Oil Heaters

A

B C

8-1/32”

12-5/16”

6-1/8”

Thermostat

Type AR

Mounting Lugs

3/8” - 16

Threaded Holes -

1-1/2” Deep

1-1/4” Centers

1-3/8” Conduit

Openings

1” Pipe

Outlet

1” Pipe

Inlet

OPERATION

1. Do not heat solutions that are corrosive to the heating element

sheath or the heating chamber.

WARNING: Type NWHO Circulation Heaters are
equipped with steel heating elements and steel heat­ing chambers. It is the responsibility of the user to
know the chemical composition of the corrosive solu­tion and the character of the materials entering the
solution as well as the corrosive effect of the solution
upon the heating elements and chamber. Chromalox
cannot warrant any electric circulation heater against

failure by sheath corrosion if such failure is the result
of operating conditions beyond our control.

2. Terminal ends of heater must be protected from drippings, con-

densation, spray or direct spill-over of material. Their presence at
the terminals may damage heater electrical insulation. Liquid-tight
terminal enclosures are available to protect heater. Check with
local sales representative.

3. If foreign material is carried by the liquid flow, install suitable fil-

ters in the inlet pipe line to the heater.

4. Do not allow heater to operate when liquid flow is interrupted.

MAINTENANCE

1. WARNING: Hazard of Shock. Disconnect all power
before servicing heater.

2. Remove heating element assembly periodically to check heater
sheath for scaling, corrosion or excessive oxidation. Correct oper­ating conditions to minimize sheath deterioration.

3. Periodically check temperature control and limit control operation
to insure accurate and safe process operation.

4. Check all electrical connections periodically and retighten connec-

tions which may have loosened in service. Replace wire terminals
that show signs of oxidation which would interfere with establish­ment of reliable electrical connections.

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-3 is
provided with mounting lugs to support the heating chamber. (See
photo.)

4. By using a slotted mounting assembly on either of the lugs, the
heater chamber will be permitted to expand with increasing tem­perature.

5. DANGER: Hazard of Fire. Provide minimum of 6” spacing

from chamber and related piping to nearest combustible material.

Do not operate near combustible fluids or in combustible vapor or
gas laden atmosphere.

6. Provide adequate space at terminal end to permit withdrawal of the

heater from chamber should servicing be required.

INSTALLATION

WARNING: Hazard of Shock. Any installation involving

electric heaters must be effectively grounded in
accordance with the National Electrical Code to elim­inate shock hazard.

1. Be sure line voltage matches heat voltage (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.

3. Power controllers must be used when heaters are rated 3 phase and
when the heater amperage exceeds the rating of the thermostat.

4. Refer to Wiring Diagram, Table B, to properly connect the heater.

Wiring Diagrams — Table B

Note: Use wire size and type specified by N.E.C. 480V and 550V heaters require 600V wire, per

N.E.C. Contactors and wire supplied by customer.

WIRING

L1

L2

L3

Ground

Contactor

Thermostat

120V

or

240V

240V, 1Ø 240V, 3Ø ss 480V, 1Ø 480V, 3Ø ss

Model Fig. Fig. Fig. Fig.

NWHO-3301 2 1 2 1
NWHO-3451 2 1 2 1
NWHO-3601 2 1 2 1
NWHO-3751 2 1 2 1
NWHO-3901 2 1 2 1
NWHO-3031 2 1 2 1
NWHO-3041 2 1 2 1

Note: Dotted lines indicate “customer furnished.” However, Thermostat could have been furnished by Chromalox if so specified on the order.

Figure 1

240V, 480V 3Øss

Figure 2

240V, 480V, 1Ø

Use contactor when the heater amperage exceeds
the rating of the thermostat.

Ground

Contactor

Thermostat

Line

120V

or

240V