OMM-0153_E
• 5/11/2023 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 30 of 124
CENTURION Installation, Operation & Maintenance Manual
SECTION 2: INSTALLATION
2.12.1 Ducted Combustion Air
For ducted combustion air installations, the air ductwork must be attached directly to the air inlet
connection on the sheet metal enclosure. Consult the
Centurion Venting and Combustion Air
Design Guide,
TAG-0102 when designing combustion air ducting.
In a ducted combustion air application, the combustion air ducting pressure losses must be
taken into account when calculating the total maximum allowable venting run. When using the
unit in a ducted combustion air configuration, the minimum diameter connection at the unit is 8-
inch (20.3 cm) duct diameter connection.
2.13 Sequencing Isolation Valve Installation
Centurion units are pre-wired with a connection for an optional, external, actuator-controlled
Sequencing Isolation Valve (P/N
21008C
). This valve is an integral component of the on-board
Water Heater Management (WHM) solution. WHM allows sites with multiple Water Heaters to
designate one unit as
the “WHM Manager” and the others as “WHM Clients.” WHM mode
ensures that the system flow will be divided between at least 2 units as demand increases,
which ensures that the efficiency of the entire Water Heater array is maximized.
In addition, WHM ensures that all units receive equal run time, with additional Water Heaters
activated based on the Co
ntroller’s
Next On Valve Pos
parameter (see
Main Menu
→
Advanced Setup
→
WHM Cascade
→
Operating Controls
→
Sequencing Control
).
In the case of pre-heated DHW systems with multiple units, it is highly recommended to lower
the
Next On Valve Pos
parameter to 30-40% (Default=50%) so that subsequent Water Heaters
are engaged sooner to provide more rapid response and divide the system flow over additional
units. In DHW pre-heat systems, the required temperature rise through an individual unit can be
much lower to ensure that flow per unit does not exceed 50 gal. (189 L) per minute.
Once system load is satisfied and all Client units have stopped firing, the WHM Manager opens
the Sequencing Valves of units specified in
Min Unit
settings in
Main Menu
→
Advanced
Setup
→
WHM Cascade
→
Cascade Comm
.
The implementation of WHM, and the installation and use of this valve, is optional. However,
when WHM is implemented
,
use of this valve is
strongly recommended
.
Installation consists of installing the Sequencing Valve in the hot water outlet pipe, and then
connecting it to the pre-wired connector on the shell harness, as described below.
NOTE:
The pre-programmed Sequencing Valve control is installed on units that are part of a
Water Heater Management group. See
SECTION 8: WATER HEATER MANAGEMENT
.
WHM Sequencing Isolation Valve Installation:
1. Remove the Sequencing Isolation Valve from the shipping container.
2. Attach valve to the water outlet of the unit using the pipe union and nipple provided.
3. Ensure valve is positioned with the actuator enclosure position as shown in Figure 2-18:
Sequencing Valve Installation.
4. PVI recommends that another pipe nipple and flange be attached to the valve inlet prior to
connecting the water piping.
5. Tighten all pipe connections after the valve is properly positioned.
6. Connect the 5-pin Molex connector on the valve to the mating connector on the Centurion
harness at the rear of the unit.
