Weil-McLain CGi 4 Series Manual page 28

CGi
SERIES 4 — GAS-FIRED WATER BOILER —
4d
Piping — low temperature systems
SYSTEM-bypass piping
method
This piping method is called a
because part of the circulator flow bypasses the
system (through valve
water from the boiler outlet mixes with cooler sys-
tem return water temperature in order to provide
minimum 130°F return water to the boiler. Valve
will most often be full open, but may need to be
7b
slightly closed on some low pressure drop systems
in order to cause enough flow through valve
Figure 24
vides return water temperature control for boilers
installed on
content or steam systems).
apply the piping of
Do not
heating systems
the water temperature provided to the system and
could result in excessive water temperature in the
radiant tubing.
System-bypass piping as shown in
be used with either zone valve or circulator zoning.
When used with circulator zoning however, the
boiler circulator (item
28
system-bypass
). This bypassed hot
7a
is an alternative piping method that pro-
converted gravity systems
Figure 24
. It provides no method regulating
), must be piped as shown.
3
Failure to
prevent low return water temperature
sion 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
return water temperature
by an
injection 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
door reset control.
boiler return water temperature
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
It cannot be used as one of the zoning circulators.
Do not apply system-bypass piping if the reduced
flow in the system could cause poor heat distribu-
tion. That is, system-bypass piping reduces the
flow in the system and increases the water tem-
perature supplied to the system. This can cause
increased heat from radiators at the beginning of
the system and reduced heat from radiators near
the end of the system.
. Valve adjustment
7a
1. Start with valve
2. Gradually open valve
(large water
until the temperature at gauge
130°F at all times.
on
radiant
3. Valve
water mixed with return water. Valve
a pressure drop in the system needed to bal-
ance flow through valve
4. The valve adjustment should be done with the
can
Figure 24
system at the coldest expected temperature
(60°F for converted gravity systems or high
mass radiant systems).
and the
system supply temperature
).
system supply temperature
Instead,
provide controls and piping
at
no less than 130°F
(continued)
fully closed and
7a
while closing valve
7a
8
regulates the amount of boiler supply
7a
and the system.
7a
to the boiler could cause corro-
regulating the boiler
(such as provided
is
relatively constant.
which can
regardless of system supply
to the boiler could cause corrosion
Part Number 550-142-302/0124
fully open.
7b
7b
reads at least
causes
7b
out-
regulate the