P/N 42-9450 8/08 Copyright 2008 Hydrotherm
Page 16 KN INSTALLATION AND OPERATION INSTRUCTIONS
Water piping (continued)
Figure 12 Suggested piping — multiple boilers — parallel- ow piping, reverse-return headers
Multiple boilers, parallel ow
Sizing and ow control
Size the boiler/system circulator to handle the ow needs of all zones. If
using variable speed control of the boiler/system circulator, ensure that the
ow never drops below the total minimum for all boilers connected. Do
not exceed the maximum ow of 50 GPM through any boiler.
DHW operation, when required
When heating system boilers are piped in parallel as in Figure 12, connect
the DHW tank as a zone o of the main header or install boilers dedicated
to the DHW application.
LEGEND • • • • • • •
1 KN boiler
4 Boiler/system circulator
5 Indirect- red DHW tank
(when used)
6 DHW circulator
8 Cold water 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 ing on closed-type expansion
systems.)
11 Low water cut-o (when required)
12 Extra high limit (when required)
16 Boiler postpurge circulator (see page 11) KN
-
2 only
17 Header sensor, required
Isolation valve
Temperature gauge
5
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