Weil-McLain CGi 4 Series Manual page 26

CGi
SERIES 4 — GAS-FIRED WATER BOILER —
4d
Piping — low temperature systems
BOILER-bypass piping
method
This piping method (
bypass because part of the circulator flow is bypassed
around the boiler (through valve
reduces the flow rate throughout the boiler, in order to
raise the average water temperature in the boiler enough
to prevent flue gas condensation. Boiler-bypass piping
is effective for some boilers — including the CGi —
provided the flow rates are adjusted according to the
instructions following.
Figures 22
for
converted gravity
systems) or
primary/secondary piping can't be applied. (
is another alternative, using system bypass in place of
boiler-bypass piping.
for radiant heating applications because it does not
protect the radiant system from possible high water
temperature.)
Boiler-bypass piping keeps system flow rate as high as
possible and temperature drop as low as possible, help-
ing to equalize the building heat distribution.
Temperature gauges
Gauge
4a
26
or ) is called a
Figure 22 23
). This method
7a
and are alternative piping suggestions
23
(large water content or steam
— for use when
radiant heating system
however, is not suitable
Figure 24
is optional if the bypass valves will be ad-
Failure to
prevent low return water temperature
of the boiler sections or burners, resulting in severe personal injury, death or substantial
property damage.
Radiant heating system piping should include a means of
water temperature
tion pumping control
Boiler return water temperature will be adequately controlled using the methods shown
in this manual provided the
apply the methods of this manual if the system is equipped with an
DO NOT
Instead,
reset control.
turn water temperature
Contact your Weil-McLain representative for suggested piping and control methods.
Failure to
prevent cold return water temperature
damage to the sections or burners, resulting in possible severe personal injury, death or
substantial property damage.
Boiler Manual
justed using cold (or room temperature) return water
to the boiler. (When setting the valves without gauge
installed — using cold or room temperature water
4a
— assume the return water temperature to be 60°F. Set
boiler-
the valves so gauge
Gauge is optional on converted gravity systems, but
4b
on radiant heating systems — to display the
required
water temperature being supplied to the radiant tubing.
Gauge is
8 required
adjustment of the bypass valves. The boiler-mounted
temperature/pressure gauge can be used if a separate
temperature gauge is not installed.
Valve adjustment
1. Start with valve
Figure 24
2. Gradually open valve
until the temperature at gauge
than gauge
through the boiler assures a low enough flow rate
and high enough average temperature to prevent
condensation even with low system return water
temperature.
3. Valve
7a
regulates the boiler flow rate.
7b
4. The boiler-mounted temperature/pressure gauge
may be used in place of a separate gauge
and the
system supply temperature
).
system supply temperature
provide controls and piping
at regardless of system supply temperature.
no less than 130°F
(continued)
reads at least 120°F.
8
on all systems to assure reliable
fully closed and
7a 7b
while closing valve
7a
reads 60 °F higher
8
. A minimum 60°F temperature rise
4a
regulates the system flow rate, while valve
to the boiler could cause corrosion
regulating the boiler return
(such as provided by an
is
relatively constant.
which can
regulate the boiler re-
to the boiler could cause corrosion
Part Number 550-142-302/0520
fully open.
7b
.
8
injec-
outdoor