Part Number 550-142-302/0520
CGi
SERIES 4 — GAS-FIRED WATER BOILER —
Boiler Manual
23
Water piping — multiple zones
(continued)
4c
Figure 18
Zoning with circulators
— return water 130°F or higher.
Figure 19
Zoning with zone valves
— return water 130°F or higher.
1
Boiler isolation (balancing) valves
2
Flow/check valve
3
System or zone circulator
5
Zone valve
6
Drain valve
9
Relief valve
10
Automatic air vent (with diaphragm-type expansion tank), or con-
nect 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 loca-
tion of expansion tank circulator or air separator.
For systems with possible low return-water temperature (such as converted gravity systems,
radiant heating systems and heat pump systems), refer to the special piping suggestions of
Figures 20 – 24
, as applies. Failure to prevent sustained low return water temperature to
the boiler could cause corrosion of the boiler sections, resulting in severe personal injury,
death or substantial property damage.