®
Chromalox
SERVICE REFERENCE
Installation
DIVISION
SALES
4
SECTION NHWO
(Supersedes PE406-4)
and
REFERENCE
PE406-5
RENEWAL PARTS IDENTIFICATION
161-048710-001
DATE
FEBRUARY, 1999
1-3/8” Conduit
Openings
12-5/16”
Type NWHO-3 Series Circulation Heaters
(for Regular and Fuel Oil Heating)
8-1/32”
1” Pipe
Outlet
Specifications — Table A
Thermostat
Type AR
Regular Oil Heaters
Dimensions (In.)
A
Mounting Lugs
B
C
3/8” - 16
Model
Volts
Phase
kW
W/In2
A
B
C
Threaded Holes -
1-1/2” Deep
1-1/4” Centers
NWHO-33015
NWHO-34515
NWHO-36015
NWHO-37515
NWHO-39015
3
4.5
6
7.5
9
32-15/16
32-15/16
42-15/16
55-7/16
55-7/16
22-1/2
22-1/2
32-1/2
45
16-1/2
16-1/2
26-1/2
39
240 or 480
1 or 3 s
23
45
39
Fuel Oil Heaters
1” Pipe
Inlet
NWHO-30315
NWHO-30415
NWHO-30615
3
4
6
32-15/16
42-15/16
55-7/16
22-1/2
32-1/2
45
16-1/2
26-1/2
39
240 or 480
1 or 3 s
15
6-1/8”
GENERAL
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.
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 solu-
tion circulation heater intended for use indoors. It is designed for 150
psig at 550˚F per ANSI standards.
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 installa-
tion is the responsibility of the user, Chromalox will be
glad to make equipment recommendations.
The 3 steel-sheathed tubular elements are centered in a 3” diame-
ter steel heating chamber and welded to a removable steel flange. The
assembly is surrounded by 1-1/2” insulation and sheet metal jacket.
INSTALLATION
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.
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.
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.)
Correct
Incorrect
Correct
Incorrect
Figure A — Vertical Mounting
Figure B — Horizontal Mounting
© 2010 Chromalox, Inc.
RENEWAL PARTS IDENTIFICATION
Regular Oil Heater
Phase
Fuel Oil Heater
Phase
Heating
Elements
Heating
Elements
Model
Volts
kW
Model
Volts
kW
NWHO-33015
NWHO-33015
NWHO-33015
NWHO-33015
240
240
480
480
1
3
3
3
3
155-024796-031
155-024796-032
155-024796-033
155-024796-034
NWHO-30315
NWHO-30315
NWHO-30315
NWHO-30315
240
240
480
480
1
3
3
3
3
155-024796-066
155-024796-067
155-024796-068
155-024796-069
3 s
1
3 s
1
3 s
3 s
NWHO-34515
NWHO-34515
NWHO-34515
NWHO-34515
240
240
480
480
1
4.5
4.5
4.5
4.5
155-024796-036
155-024796-037
155-024796-038
155-024796-039
NWHO-30415
NWHO-30415
NWHO-30415
NWHO-30415
240
240
480
480
1
4
4
4
4
155-024796-071
155-024796-072
155-024796-073
155-024796-074
3 s
1
3 s
1
3 s
3 s
NWHO-36015
NWHO-36015
NWHO-36015
NWHO-36015
240
240
480
480
1
6
6
6
6
155-024796-041
155-024796-042
155-024796-043
155-024796-044
NWHO-30615
NWHO-30615
NWHO-30615
NWHO-30615
240
240
480
480
1
6
6
6
6
155-024796-081
155-024796-082
155-024796-083
155-024796-084
3 s
1
3 s
1
3 s
3 s
NWHO-37515
NWHO-37515
NWHO-37515
NWHO-37515
240
240
480
480
1
7.5
7.5
7.5
7.5
155-024796-046
155-024796-047
155-024796-048
155-024796-049
3 s
1
Parts Common To All Heaters
3 s
Standard Gasket . . . . . . . . . . . . . . . . . . . . . . . . . .132-017222-015
Spiral Wound Gasket . . . . . . . . . . . . . . . . . . . . . . .132-073008-009
Thermostat (Regular Oil) . . . . . . . . . . . . . . . . . . . .300-057502-015
Thermostat (Fuel Oil) . . . . . . . . . . . . . . . . . . . . . .300-057502-016
NWHO-39015
NWHO-39015
NWHO-39015
NWHO-39015
240
240
480
480
1
9
9
9
9
155-024796-051
155-024796-052
155-024796-053
155-024796-054
3 s
1
3 s
Note: When ordering parts for Model Numbers suffixed by “XX” or any other letters not specifically identified on this instruction sheet, order Renewal Parts on special order basis, giving
name of part, part number, model number and description.
Limited Warranty:
Please refer to the Chromalox limited warranty applicable to this product at
2150 N. RULON WHITE BLVD., OGDEN, UT 84404
Phone: 1-800-368-2493
99 - 050
TA - P9 - EF
Litho in U.S.A.
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