Figure 17 Zoning with
circulators
— return water 130°F or higher.
Figure 18 Zoning with
zone valves
— return water 130°F or higher.
4c
23
Part Number
550-110-290/0219
CGt
GAS-FIRED WATER BOILER — Series 2 —
Boiler Manual
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
13
Air separator with automatic vent, if used (Note that the fill valve
must always be connected to the expansion tank.)
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 19 – 20
, page 25, as applies. Failure to prevent sustained low return water tempera-
ture to the boiler could cause corrosion of the boiler sections, resulting in severe personal
injury, death or substantial property damage.
Water piping — multiple zones
(continued)