Specifications

Part number 550-100-090/0809
g a s -f i r e d w a t e r b o i l e r — Boiler Manual
78
Field wiring — advanced
ondary heat source when another heat source, such
as a heat pump or another boiler is available.
Connect to remote alarm, when used

Connect wiring for multiple boiler operation

The U-Control provides the flexibility for control •
of multiple Ultra boilers.
You will need to program the boilers’ U-Controls •
based on the interconnection method you choose.
Install system & outdoor sensors, when used

The boiler is shipped with an outdoor sensor, a •
system supply sensor and a system return sensor.
The system supply sensor will be required for most
space heating applications. The system return sensor
must also be installed when using the system supply
sensor. Use of the outdoor sensor is optional.
Line voltage power input
Provide and install a fused disconnect or service switch 1.
(15-ampere rated recommended) as required by ap-
plicable codes.
Connect minimum 15-ampere, 120 VAC power wiring 2.
to Ultra boiler line voltage terminal strip as shown in
Figure 98, page 80 and above.
Wiring circulators
The U-Control provides for connection of up to three 1.
circulators, one of which must be the boiler circulator.
In addition, you can connect a system circulator and a
DHW circulator, for examples. See Figure 97, page 79.
The maximum allowable current for each
circulator is 2.2 amps at 120 VAC
. For
circulators with higher amp ratings, you must
install a circulator relay or starter to provide
line voltage to the circulator. For circulators
rated over 2.2 amps, connect only the circula-
tor relay or starter coil to the Ultra circulator
terminals.
You can connect any of the circulators you use to any of 2.
the three circulator activation terminals. The U-Control
setup allows you to assign which circulators activate on
a call for heat (this can be customized for each of the
heating systems supplied by the boiler).
The U-Control factory 3.
default settings for DHW heat-
ing are configured for direct piping to the boiler, with
Circulator 1 being the only circulator being activated
Wiring — general
The U-Control provides plug-in, color-coded, non-interchangeable 1.
terminal strips for all field wiring. See the schematic diagram (Fig-
ure 98, page 80) & ladder diagram (Figure 99, page 81).
The U-Control provides programmable flexibility in system op-2.
eration, allowing control of heat supply for up to three different
heating systems. Read this manual thoroughly before connecting
the wiring to ensure trouble-free start-up and operation.
Wiring — overview
You will need to make the following connections, some of which
depend on your system and how the U-Control will be programmed.
(See this and following pages for more information.)
Connect 120VAC power (minimum 15-amp source)

Connect wiring for up to three circulators

Connect external limits, if used
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Two different circuits are available — The U-Control will •
require manual reset for one of these circuits. The U-Control
will automatically reset after limit operation and re-closure for
limits in the other circuit.
Connect thermostats and/or heat demand contacts

The U-Control can regulate the boiler for up to three different •
heating systems.
Connect remote operation input, if used

The U-Control will operate and modulate the boiler based •
on a 0–10 VDC control signal from a remote controller, when
desired.
Connect the “additional heat demand” circuit to a second

heating source, when used
The U-Control allows the boiler to act as the primary or sec-•
ELECTRICAL SHOCK HAZARD — For your
safety, turn off electrical power supply at service
entrance panel before making any electrical connec-
tions to avoid possible electric shock hazard. Failure
to do so can cause severe personal injury or death.
Wiring must be N.E.C. Class 1. If original wiring as
supplied with boiler must be replaced, use only type
105 °C wire or equivalent. Boiler must be electrically
grounded as required by National Electrical Code
ANSI/NFPA 70 – latest edition.
Installation must comply with:
1. National Electrical Code and any other national, state, provincial or
local codes or regulations.
2. In Canada, CSA C22.1 Canadian Electrical Code Part 1, and any local
codes.