Weil-McLain CGi 4 Series Manual page 22

CGi
SERIES 4 — GAS-FIRED WATER BOILER —
4c
Water piping — multiple zones
Piping multiple zones
Follow instructions on pages 20 and 21 to install near-
boiler or single-zone piping. (Also refer to
radiant heating systems or converted gravity sys-
, below, if applicable.)
tems
See
Figure 18
Zoning with circulators (Figure 18)
(return temp over 130°F)
1. Size each circulator to individual circuit require-
ments.
2. Do not install circulator on boiler (except for
primary/secondary piping).
3. Install isolation (balancing) valves to adjust flow
to distribute heat to all zones.
4. Install and wire a separate relay for each zone
circulator.
Zoning with zone valves (Figure 19)
(return temp over 130°F)
1. Install isolation (balancing) valves to adjust flow to
distribute heat to all zones.
2. Provide a separate 24-volt transformer to power the
zone valves. Size the transformer to handle the total
rated load of all connected zone valves.
22
or to complete installation.
Figure 19
DO NOT connect directly from
3-wire zone valves to the T-T termi-
nals on the boiler . When using 3-wire
zone valves, install an isolation relay.
Connect the zone valve end switch wires
to the isolation relay coil. Connect the
isolation relay contact across the boiler
T-T terminals. Failure to comply can
result in damage to boiler components
or cause unreliable operation, resulting
in severe property damage.
Radiant heating system piping should include a means of regulating the boiler return water
temperature and the system supply temperature (such as provided by an injection pumping
control). Boiler return water temperature will be adequately controlled using the methods
shown in this manual provided the system supply temperature is relatively constant.
apply the methods in this manual if the system is equipped with an
DO NOT
. Instead, provide controls and piping which can regulate the boiler return water
control
temperature at no less than 130°F regardless of system supply temperature. Contact your
Weil-McLain representative for suggested piping and control methods. Failure to prevent
cold return water temperature to the boiler could cause corrosion damage to the sections
or burners, resulting in possible severe personal injury, death or substantial property damage.
Boiler Manual
Piping for radiant heating
systems or converted gravity
Piping for
systems
Converted gravity (or steam) systems
Whenever possible, use the primary/secondary piping
shown in
Figures 20 or 21
sign allows changing boiler flow rate without affecting
primary circuit flow rate.
If
Figures 20 or 21
pass piping shown in
You can also use the piping shown in
page 29 (system-bypass), if the reduced flow rate in
the heating system will not cause heat distribution
problems.
Radiant heating systems
Preferably, use primary/secondary piping, as shown
in Figures 20 or 21
method of either
Do not use the piping of Figure 24
because this method does not control radiant system
supply temperature.
If radiant system tubing has no oxygen barrier, a
must be used.
exchanger
on page 25. This piping de-
cannot be used, use the boiler-by-
on page 27.
Figure 22 or Figure 23
Figure 24
Failure to prevent low return water
temperature to the boiler could
cause corrosion of the boiler sec-
tions or burners, resulting in severe
personal injury, death or substantial
property damage.
on page 25. Alternatively, use the
on page 27.
Figure 22 or Figure 23
(system-bypass),
outdoor reset
Part Number 550-142-302/0520
on
heat