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
Piping for radiant heating systems or converted
gravity systems
See
Figure 18
Zoning with circulators (Figure 18)
(return temp over 130°F)
1. Size each circulator to individual circuit re-
quirements.
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
Boiler Manual
, below, if applicable.)
or to complete installation.
Figure 19
DO NOT connect directly from
3-wire zone valves to the T-T
terminals on the boiler
using 3-wire zone valves, install an
isolation relay. Connect the zone
valve end switch wires to the isola-
tion relay coil. Connect the isolation
relay contact across the boiler T-T
terminals. Failure to comply can re-
sult in damage to boiler components
or cause unreliable operation, re-
sulting in severe property damage.
Radiant heating system piping should include a means of regulating the boiler re-
turn 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.
DO NOT apply the methods in this manual if the system is equipped with an out-
door reset control. Instead, provide controls and piping which can regulate the
boiler return water 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.1
Piping for radiant heating
systems or converted grav-
ity systems
Converted gravity (or steam) systems
Whenever possible, use the primary/secondary
piping shown in
piping design 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 distribu-
tion problems.
Radiant heating systems
Preferably, use primary/secondary piping, as
shown in
Figures 20 or 21
tively, use the method of either
on page 27.
23
(system-bypass), because this method does not
control radiant system supply temperature.
. When
If radiant system tubing has no oxygen barrier, a
heat exchanger
on page 25. This
Figures 20 or 21
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 boil-
er sections or burners, resulting
in severe personal injury, death
or substantial property damage.
on page 25. Alterna-
Figure 22 or Figure
Do not use the piping of Figure 24
must be used.
Part Number 550-142-302/0124
on