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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 8
Suggested piping — single boiler — zone valve zoning — two-pipe or series loop (left), or primary/secondary piping (right)
L
EGEND
• • • • • • •
1
200i
boiler
2
Boiler
circulator
3
System
circulator
4
Boiler/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)
13
Zone valve
14
Zone circulator
15
Diff erential pressure by-pass valve — Use when high-
head circulator may cause noise, erosion or valve lift ing
problems when only a few zone valves are open.
16
Boiler postpurge circulator (see page 11)
17
Header sensor, required where shown
Isolation valve
Purge valve — Suggested locations allow for improved
system fi lling and draining and initial air elimination.
Temperature gauge
Zoning with zone valves
Flow balancing and control
On large systems, or when using a high-head circulator, install a diff erential
pressure by-pass valve to limit the head applied to the zone valves.
Some systems may require balancing valves to control fl ow in the loops.
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.
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