14
Part Number 550-142-320/0720
GWA
Series 3
Gas-Fired Water Boilers –
Boiler Manual
4 Water piping — multiple zones
continued
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
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 waterlog-
ging 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 6, page 11.)
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.
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 12 – 15
, 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.
Figure 10
Zoning with circulators — return water 130°F or
higher.
Figure 11
Zoning with zone valves — return water 130°F
or higher.
