AIR 1-550.30
6
Figure 6.1 - Suggested Piping Arrangements
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Steam Systems
Unit Heater Connection for High Pressure Steam
Horizontal Unit Heater Connected to
Overhead Hot Water Mains
Vertical Unit Heater Connected to
Lower Hot Water Mains
Unit Heater Connection for Low-Pressure Steam
Open Gravity or Vacuum Return System
INSTALLATION / OPERATION
Hot Water Systems
Electrical Connections (Cont.)
2. Electric wiring must be sized to carry the full load amp draw
of the motor, starter, and any controls that are used with
the unit heater. All units with power codes 04, 05, 09, or
10 (polyphase motors) must be provided with suitable
overcurrent protection in circuit supplying heater at
installation. Overcurrent protectors should be sized based
on motor current rating shown on the unit serial plate, and
applicable national electric code procedures.
All units are provided with an electrical junction box.
Junction boxes are either integral to the motor or attached
to the unit casing. Units with explosion-proof motors have
an explosion-proof junction box attached to the motor.
Any damage to or failure of Modine units caused by
incorrect wiring of the units is not covered by Modine’s
standard warranty.
3. Location of room thermostat, when supplied, should be in
the natural circulating path of room air. Mount thermostat
about five feet above floor level where it will not be affected
by heat from the unit or other sources of drafts that would
prevent it from properly controlling room temperature. See
instructions packed with the thermostat.
4. Speed controllers furnished with specified unit heater fan
motors, are packed separately and must be connected
according to wiring diagram with each controller.
Prior to Operation
1. Make sure fuses are installed in fused disconnect switches.
2. Check all electrical connections to assure they are secure.
3. Check rigidity of unit mounting. Tighten all fasteners,
if necessary.
4. Inspect piping, strainers, traps, fittings, etc.
Initial Start-Up
1. Set thermostat to lowest position.
2. Turn on power supply to unit.
3. Open return gate valve, and then open supply gate valve
to unit.
4. Raise thermostat setting to desired position.
5. Adjust louvers (if provided) for desired heat distribution.
6. To ensure proper sequence of operation, cycle unit on and
off a few times by raising and lowering thermostat setting.
7. Check for proper rotation of fan. All fans must rotate in a
counterclockwise direction when viewed from the back
(WTC/WSC, WPC/WPN) or top (WVC/WVN) of the unit
heater.
Automatic Control Operations
Install one of the following operating systems for continuous
automatic control.
Intermittent Fan Operation — Hot Coil
A room thermostat starts and stops the fan motor. An aquastat
is sometimes strapped to the return piping to prevent fan
operation when heat is not being supplied to the unit heater.
Continuous Fan Operation — Intermittent Hot/Cold Coil
A room thermostat controls a valve which opens to allow steam
or hot water to supply the unit and closes to shut off the supply
when the thermostat is satisfied.
OPERATION
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Arrangements shown are recommendations only. Where horizontal units are shown, vertical units can be substituted or vice versa. For modifications to piping
suggestions shown, refer to your local plumbing authority.
Model WSC
Side Connections
Model WTC
Top and Bottom Connections
Model WTC
Top and Bottom Connections
Model WSC
Side Connections
Model WTC
Side Connections
Model WSC
Top and Bottom Connections
