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IOM-DHI (Supersedes 7/05)
INSTALLATION INSTRUCTIONS FOR
NAILOR ELECTRIC DUCT HEATERS
Nailor Industries Inc. reserves the right to change any information concerning product or specification without notice or obligation.
Page 1 of 2
The information and instructions in this manual apply to Nailor DH
Series Electric Duct Heaters, Models DHRS (slip-in), DHRF
(flanged) and DHRR (Round). These heaters are designed for
installation in horizontal ducts with zero clearance between the
duct and combustibles.
Nailor Electric Duct Heaters are completely prewired when they
leave Nailor's modern factory. Voltage ratings can be as high as
600 volts either both single or three phase.
Standard models are furnished with integral controls while heaters
ordered with DRP option are furnished with a remote controls
panel. Field wiring will be required for the interconnection of the
heater and the remote control panel. Terminal blocks for field
connections are supplied as standard.
Figure 1: DHRS Slip-In Heater
Figure 2: DHRF Flanged Heater
WRAPPER
CONTROLS
ENCLOSURE
HEATING
ELEMENTS
DOUBLE
LIP
1"
(25)
WRAPPER
1"
(25)
HEATING
ELEMENTS
CONTROLS
ENCLOSURE
Figure 4: Airflow Switch Pick-up Probe.
AIRFLOW
DIRECTION
NOTE:
PROBE IS TO BE
INSTALLED FACING
THE AIRFLOW
AIR FLOW
MOUNTING
FLANGE
MOUNTING
SCREW
MOUNTING PLATE
(END VIEW)
Figure 3: DHRR Round Heater
CONTROLS
ENCLOSURE
ROUND DUCT
INSTALLS OVER
THE INLET COLLAR
GENERAL:
Inspect heater for any possible shipping damage. Check all
insulators for breakage and inspect heater element wire for any
deformation that would cause short circuits or grounding. Make
sure all fasteners are tight.
Before installing a slip-in, flanged or round heater, check the
airflow direction in the ductwork. The Airflow Switch Pick-up Probe
must be installed facing the airflow (see Figure 4). If these two
directions are opposite of each other, remove the two screws
securing probe mounting plate, rotate 180 degrees, and reinstall.
Then mark the correct airflow arrow on the front of the control panel
label (see Figure 5).
Important Note: Even though heaters can be rotated in either
direction horizontally, those ordered with the mercury contactor
option are position sensitive. As a result, before installing heaters
with mercury contactors, inspect the position of the mercury contactors
in the control enclosure. Mercury contactors must be heading up
90 degrees vertically. If they are heading down, unscrew the
mercury contactors, rotate 180 degrees and reinstall them.
