15
P/N 42-9470 11/07 Copyright 2007 Mestek, Inc.
Cast iron condensing boiler
Cast iron condensing boiler
— Installation and operation manual
Water piping
(continued)
Figure 11
Suggested piping — multiple boilers — primary/secondary piping, reverse-return boiler headers
Multiple boilers, primary/secondary
Sizing and fl ow control
Size circulators to provide the fl ow needed for the individual zones.
Provide fl ow/check valves where shown to prevent gravity circulation or
forced fl ow in idle zones.
DHW operation, when required
Th
e piping shown throughout this manual allows for domestic water heating
without fl ow through the heating loop(s). Th is is important for summer-
time operation of DHW tanks.
Make sure to incorporate fl ow/check valves as shown. Th ese prevent forced
fl ow in idle zones.
L
EGEND
• • • • • • •
1
200i
boiler
2
Boiler
circulator
3
System
circulator
5
Indirect-fi red DHW tank
(when used)
6
DHW
circulator
7
Flow/check
valve
8
Cold water fi ll line
9
Expansion tank (shown with diaphragm-type — see
page 12 for piping a closed-type tank) Expansion tank
(shown with diaphragm-type — see page 12 for piping
a closed-type tank)
10
Air separator with automatic air vent (Replace air vent
with piping to the tank fi tt ing on closed-type expansion
systems.)
11
Low water cut-off (when required)
12
Extra high limit (when required)
16
Boiler postpurge circulator (see page 11)
17
Header sensor, required
Isolation valve
Temperature gauge
5