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Part number IWHA016A/1103
3
PLUS Line Instruction Manual Supplement
PLUS &
PLUS WATER HEATERS WITH GAS-FIRED WATER BOILERS
System water piping methods
All piping methods shown in this manual
use primary/secondary connection to the
boiler loop. These designs ensure proper
flow through the Ultra boiler, for the most
efficient and reliable operation of the boiler
and the heating system. For other piping
methods, consult your local Weil-McLain
representative or refer to separate Ultra
boiler piping guides.
Wall-mounted boilers — Piping can exit
bottom of boiler enclosure. See separate
wall-mounting instructions for details.
Expansion tank and make-up water
1. Ensure expansion tank size will handle boiler and
system water volume and temperature. Allow 3
gallons for boiler and its piping.
Undersized expansion tanks cause system
water to be lost from relief valve and
make-up water to be added through fill
valve. Eventual boiler failure can result
due to excessive make-up water addition.
2. Tank must be located as shown in this supplement,
or following recognized design methods. See tank
manufacturer’s instructions for details.
3. Connect the expansion tank to the air separator
only if the separator is on the suction side of the
system circulator. Always install the system fill
connection at the same point as the expansion tank
connection to the system.
4. The piping drawings in this supplement show
diaphragm expansion tanks. See Figure 1 for piping
from air separator to expansion tank and make-up
water line using a closed-type expansion tank.
5. Refer to Ultra Boiler Manual for other system
piping examples.
Diaphragm (or bladder) expansion tank
1. Always install an automatic air vent on top of the
air separator to remove residual air from the system.
Closed-type expansion tank
1. See Figure 1 for piping connections when using a
closed-type expansion tank.
2. Pitch any horizontal piping up towards tank 1 inch
per 5 feet of piping. Connect to tank with at least
¾" piping to allow room for air to rise.
DO NOT install automatic air vents on
closed-type expansion tank systems. Air
must remain in the system and return to
the tank to provide its air cushion. An
automatic air vent would cause air to
leave system, resulting in water-logging
the expansion tank.
Install system water piping (space heating)1
Boiler circulator
The boiler circulator is shipped loose. It must be located
in either the return or supply piping, as shown in the
appropriate piping diagram in this supplement or the
Boiler Manual.
DO NOT use the boiler circulator in any
location other than those shown. The
boiler circulator is selected to ensure
adequate flow through the Ultra boiler.
Failure to comply could result in
unreliable performance and nuisance
shutdowns from insufficient flow.
Sizing space heat system piping
1. See Figures 2 and 3, pages 4 and 5, or the Ultra Boiler
Manual for recommended piping. In all diagrams,
the space heating system is isolated from the boiler
loop by the primary/secondary connection.
2. Size the piping and components in the space
heating system using recognized design methods.
Figure 1 Expansion tank piping