47
LP- 446 REV. 9.3.14
each tank and wire them in series to provide temperature control of the tanks. (See Piping Diagrams in Part 4 for reference.) The
control in the Mod Con VWH will read either the temperature of the tank sensor or the status of the aquastats, and cause the boiler to
run until the water temperature of the tank(s) meets the desired set point.
If a sensor or aquastat cannot be placed directly in the tank, then one sensor should be used on the pipe carrying water from the
tank(s) to the boiler. To minimize temperature loss in the piping, this sensor should be placed as close to the tank(s) as possible. The
use of a pipe sensor will be somewhat less accurate
than using a sensor in the tank, and has the
disadvantage of requiring the boiler pump(s) to run
continuously so the sensor is always measuring the
tank water temperature.
In a multiple Mod Con VWH installation, where the
boilers are connected for cascade operation, a system
sensor is needed in addition to the tank or pipe sensor
described above. The system sensor is mounted on
the common pipe to the tank(s) from the boilers as
close to the tank(s) as possible. The purpose of this
sensor is to serve as feedback to the control and
provide it with the aggregate temperature of all firing
boilers. The master boiler control will then fire the
boilers in cascade sequence to maintain the water
temperature in this pipe and provide correct tank
heating.
The electrical junction box has separate, clearly
marked terminal strips for line voltage and low voltage
wiring. Special jacks are provided for trouble-free
cascade system wiring using standard CAT3 or CAT5
patch cables.
D. LINE VOLTAGE WIRING
NOTE:
A termination plug is included in the CAT 3 /
CAT 5 Bus Connection Point, labeled J3 in Figure 29.
DO NOT REMOVE THIS PLUG! Doing so will affect
boiler operation and void warranty.
Connect the incoming power wiring to the line voltage
terminal strip in the electrical junction box at terminals
LINE 120V, Neutral, and Ground (shown in Figure 29).
A line voltage fused disconnect switch may be required
to be externally mounted and connected according to
local wiring codes.
If the pump used for the boiler operates at 120 volts
and less than 3 amps is required, it may be connected
directly to the terminals marked BOILER HOT, BOILER
NEUT, and BOILER GRD. If the pump operates at a
voltage other than 120 volts and/or requires more than
3 amps, an external motor starter must be used to
operate the pump. If the starter is equipped with a 120
volt coil, the coil connections may be connected
directly to the terminals marked BOILER HOT and
BOILER NEUT. Refer to Figure 29 for a representative
drawing of this configuration. If a motor starter is used,
it should be selected, installed, and wired in
compliance with all local electrical codes and
requirements. In the absence of such codes or
requirements, the National Electrical Code (NFPA 70)
should be followed.
E. ALARM CONNECTIONS
The Mod Con control includes a dry contact alarm
output. This is an SPDT circuit, rated at 5 amps at 120
volts. This contact can be used to activate an alarm
light or bell, or notify a building management system if
Figure 29 - Mod Con VWH Control
Содержание 500 HL
Страница 12: ...12 LP 446 REV 9 3 14 Figure 2 Dimensions and Specifications ...
Страница 21: ...21 LP 446 REV 9 3 14 H PIPING DIAGRAMS Figure 6 ...
Страница 44: ...44 LP 446 REV 9 3 14 E GAS VALVE Figure 26 Mod Con 500 Gas Valve ...
Страница 52: ...52 LP 446 REV 9 3 14 Figure 33 Mod Con Internal Connection Diagram LP 428 K ...
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