AIR 1-550.30
water systems, include a balancing valve in return line for
water flow regulation. A drain valve should also be provided
below each unit heater to allow removal of water from the
heating coil if located in an area subject to freezing.
3. In steam or hot water systems, rapid air removal is required
because entrained air is a cause of corrosion. Hot water
systems should be equipped with suitable air vent valves for
rapid and complete removal of air at the high points and ends
of both supply and return mains. Proper air venting for steam
systems can be achieved by use of a steam trap with an
internal air vent.
4. Traps must be located below the outlet of the unit. Consult
trap manufacturer for specific recommendations. Each steam
unit heater should be provided with a trap of sufficient size
and capacity to pass a minimum of two times the normal
condensate released by the unit at the minimum differential
pressure in the system. Trap capacity is based on the
pressure differential between supply and return mains. Steam
systems should be equipped with a float and thermostatic trap
or an inverted bucket trap with an air bypass.
5. It is advisable to use a pipe line strainer before each steam
trap draining a unit heater. This protection will reduce the
maintenance of the steam trap. When strainers are used they
should be installed between the unit heater and the trap and
be the same size as the trap tapping. In order to catch dirt
and scale, the strainer should have a screen perforation size
smaller than the trap orifices.
6. On systems where the steam supply to the unit heater is
modulated or controlled by a motorized valve, a vacuum
breaker should be installed between unit outlet and the trap.
If a vacuum breaker is used, it should be in conjunction with a
float and thermostatic trap.
7. Install a scale pocket at bottom of unit heater to collect dirt
and scale as shown in illustrations. Pipe diameter must be the
same size as unit connections and about 6" long.
8. Provide adequate pipe hangers, supports, or anchors to
secure the piping system independently of the unit heater.
Electrical Connections
1. Installation of wiring must conform with local building codes,
or in the absence of local codes, with the National Electric
Code ANSI/NFPA 70 - Latest Edition. Unit must be electrically
grounded in conformance to this code. In Canada, wiring must
comply with CSA C22.1, Electrical Code.
Figure 5.1 - Unit Suspension
UNIT SUSPENSION / INSTALLATION
WARNING
1. Disconnect power supply before making wiring connections
to prevent electrical shock and equipment damage.
2. All appliances must be wired strictly in accordance with
wiring diagram furnished with the appliance. Any wiring
different from the wiring diagram could result in a hazard
to persons and property.
3. Any original factory wiring that requires replacement must
be replaced with wiring material having a temperature
rating of at least 105°C.
4. Ensure that the supply voltage to the appliance as indicated
on the serial plate is not 5% greater than the rated voltage.
5
CAUTION
1. Do not install units below 8 feet measured from the bottom
of the unit to the floor.
2. Do not reuse any electrical component which has been
wet. Replace component.
3. Ensure that the supply voltage to the appliance, as indicated
on the serial plate is not 5% less than the rated voltage.
Piping - See Figure 6.1
1. Branch piping to and from unit heater should include swing
joints to allow for expansion and contraction of the piping
without placing a strain on the unit heater element. On steam
systems, the branch piping should be taken off and returned
above the centerline of the supply and return lines.
2. Install pipe unions and shut-off valves in lines to and from
each unit heater to allow maintenance or replacement of unit
without shutting down and draining entire system. For hot
UNIT SUSPENSION
Horizontal delivery units, Model WTC/WSC Series.
All
horizontal delivery units, except Models WTC 18 and WTC 24,
have two tapped holes in the top for unit suspension. WTC 18
and WTC 24 models do not require independent suspension and
are installed directly on their supply piping. Models WTC 33-86
and WSC 18-86 have 3/8"-16 tapped holes, model sizes 108
and larger have 1/2"-13 tapped holes. Piping support hangers
or clamps are recommended and should be placed as close
to the unit heater as possible. For other models, independent
suspension can be made with threaded rods, pipes, or ceiling
hanger brackets. See Figure 5.1.
Vertical delivery units.
Vertical delivery Models WVC/WVN
42 through WVC/WVN 279 have four tapped holes (1/2"-13)
in the top cover for unit suspension. Unit suspension for these
models can be made with threaded rods, pipes or ceiling hanger
brackets. Models WVC/WVN 333 through WVC/WVN 952 are
equipped with an angle-iron mounting bracket that has eight 5/8"
diameter hanger holes permitting hook-hoisting and suspension
with cables, if desired. A 1/2" x 3" center U-bolt can be inserted
in the two holes at each end of the bracket to accommodate
suspension with four threaded rods, pipes or hanger brackets.
“Power-Throw” horizontal delivery units.
“Power-Throw”
units are designed for horizontal air delivery and are equipped
with hanger brackets for suspension. Three hanger brackets are
supplied for Model WPC/WPN 279, one on the front, and two
on the rear panel for three-point suspension. Only two hanger
brackets are furnished on the front panel of Models WPC/WPN
333 through WPC/WPN 952 (for required four-point suspension
use the two hanger brackets on the front panel and the two
holes on the ends of the upper angle supports at the rear of the
unit). Each hanger bracket has a 5/8" diameter mounting hole
for hook-hoisting and suspension with threaded rods, pipes, or
cables.
Note:
A pipe hanger adapter kit as illustrated in Figure 5.1
is available as an accessory from Modine. The kit consists of
two drilled 3/4" I.P.S. pipe caps and two capscrews to facilitate
threaded-pipe suspension. One kit will mount applicable WTC or
WSC models, two kits are required for WVC/WVN models.
WVC/WVN 42 Thru WVC/WVN 279
WSC 18 Thru WSC 340
WTC 33 Thru WTC 340
Threaded Pipe
Suspension
Method
Threaded Rod
Suspension
Method
Pipe Hanger
Adapter Kit
WVC/WVN 333 Thru WVC/WVN 952
