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Chromalox
®
DIVISION
4
SECTION
NWHMT
SALES
REFERENCE
DATE
SERVICE REFERENCE
Installation, Operation
and
MAINTENANCE INSTRUCTIONS
PE439-2
161-303186-001
APRIL, 1999
(Supersedes PE439-1)
GENERAL
INSTALLATION
© 2010 Chromalox, Inc.
Type NWHMT Circulation Heater
(for Water 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.
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 2-
1/2” 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 con-
trols 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 rec-
ommendations.
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 ele-
ments 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 mount-
ing assembly on either of the lugs.
Dimensions (In.)
Model Volts Phase kW W/In
2
ABC
NWHMT-3305 1
20, 240 or 480
1 or 3 3 50 21-5/8 9-3/8 —
NWHMT-3455 240 or 480 1 or 3 4.5 50 21-5/8 9-3/8 —
NWHMT-3605 240 or 480 1 or 3 6 50 34-3/4 22-1/2 16-1/2
NWHMT-3905 240 or 480 1 or 3 9 50 34-3/4 22-1/2 16-1/2
NWHMT-31205 240 or 480 1 or 3 12 50 57-1/2 45-1/4 39-1/4
NWHMT-31505 240 or 480 1 or 3 15 50 57-1/2 45-1/4 39-1/4
NWHMT-31805 240 or 480 1 or 3 18 50 57-1/2 45-1/4 39-1/4
Specifications — Table A
Incorrect
Correct
Figure 1 — Vertical Mounting
Figure 2 — Horizontal Mounting
Correct
Incorrect
7”
ABC
3”
3”
2 Mtg. Lugs ea. with
two 3/8” - 16 x 1-1/2”
deep holes on 1-1/4”
centers
1” Pipe
Inlet (Std.)
1” Pipe
Outlet (Std.)
3/8” NPT
Pipe Plug
Internal
Thermostat
1-1/16” Dia. K.O.
for 3/4” Conduit
9-1/4”