Weil-McLain CGi 4 Series Manual page 25

CGi
SERIES 4 — GAS-FIRED WATER BOILER —
4d
Piping — low temperature systems
Figure 20 Primary/secondary piping
1 Boiler isolation (balancing) valves
2 Flow/check valve
3 System or zone circulator
4 System temperature gauges
5 Zone valve
6 Drain valve
7 System temperature valves (see
instructions to the left for adjusting
valves)
8 Blend temperature gauge
Part Number 550-142-302/0124
Boiler Manual
Zoning with circulators
Figure 21 Primary/secondary piping
Zoning with zone valves
9 Relief valve
10 Automatic air vent (with diaphragm-type expansion tank),
or connect to tank fitting (closed-type expansion tank). DO
NOT use an automatic air vent when using closed-type
expansion tank. It would allow air to leave the system,
causing waterlogging of the expansion tank.
11 Fill valve
12 Diaphragm-type or bladder-type expansion tank, if used
(For closed-type expansion tank, pipe from top of air
separator to tank fitting as in Figure 17.)
13 Air separator and automatic vent, if used (Note that the fill
valve must always be connected to the expansion tank,
regardless of location of expansion tank, circulator or air
separator.)
(continued)
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