Centurion Water Heater- Edge [ii]: Install-Operation-Service
SECTION 2: INSTALLATION
OMM-0153_A
• 8/25/2022 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 32 of 131
2.12 COMBUSTION AIR
The CENTURION
Venting and Combustion Air Design Guide,
TAG-0022 (GF-2050)
must
be
consulted before any inlet air venting is designed or installed. Air supply is a direct requirement
of ANSI 223.1, NFPA-54, CSA B149.1 and local codes. These codes should be consulted
before a permanent design is determined.
The combustion air must be free of chlorine, halogenated hydrocarbons, other chemicals that
can become hazardous when used in gas-fired equipment and other combustion products.
Common sources of these compounds are swimming pools, degreasing compounds, plastic
processing, and refrigerants. Whenever the environment contains these types of chemicals,
combustion air
MUST
be supplied from a clean area outdoors for the protection and longevity of
the equipment and warranty validation.
If combustion air is supplied directly to the unit(s) though air duct(s), see Section 2.12.1, below.
If combustion air is not supplied through air ducts, it must be supplied to the unit(s) through two
permanent openings. These two openings must have a free area of
not less than one square
inch (6.5 cm
2
) for each 4000 BTUs (1.17 kW) input
for each unit
. The free area must take
into account restrictions such as louvers and bird screens.
For Canada installations, refer to the requirements specified in Sections 8.4.1 and 8.4.3 of the
CSA B149.1-10.
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-0022 (GF-2050) 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
All 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.” Once
WHM mode has been enabled (see
Main Menu
→
Advanced Setup
→
WHM Cascade
→
Cascade Configuration
,
WHM Unit Mode
equals
WHM Manager
or
WHM Client
), operation
in 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
Controller’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.
