Weil-McLain CGi Series 3 Installation And Maintenance Manual page 23

CG i
GAS-FIRED wATER BOILER- sERIEs a -
Boiler Manual
4c
Water piping - multiple zones
(continued)
Figure 18
Zoning with circulators
Figure 19
Zoning with zone valves
- return water 130•F or higher. - return water 130•F or higher.
r----------,
.r--------------1
ZONE 2
~--------+:,.
i
----;~~~--1
.
i
ft
1 1
~~
!
l
I
5
'fD
+
~·
+---
--!-'
6
10
Cold
Cold
water
wttter
fill
fil
~
Ei:l
II
II
71020
71 021
1 Boiler isolation (balancing) valves
10 Automatic air vent (with diaphragm-type expansion tank), or con-
nect to tank fitting (closed-type expansion tank). DO NOT use an
auto matic air vent when using closed-type expansion tank It would
allow air to leave the system, causing waterlogging of the expansion
tank.
2 Flow/check valve
3 System or zone circulator
11 Fill valve
5 Zone valve
6 Drain valve
9 Relief valve
I&WARNINGl
12 Diaphragm-type or bladder-type expansion tank, if used (For
dosed-type expansion tank, pipe fro m top of air separato r to tan k
fitting as
Ill
Figure
17.)
13 Air separator and auto matic vent,
if
used (Note that the fill valve
must always be connected to the expansion tank, regardless of loca-
tion of expansion tank circu1ator 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 corrosio n of the boiler sections, resulting in severe personal injury,
death or substantial property damage.
Part
Number 550-142-780/0712 23