Install Instructions

Part Number 550-142-902/1016
CGi
GAS-FIRED WATER BOILER — SERIES 3 — Boiler Manual
22
4c
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 sys-
tems
, below, if applicable.)
SeeFigure 18 or Figure 19 to complete installation.
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.
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.
Piping for radiant heating
systems or converted gravity
systems
Converted gravity (or steam) systems
Whenever possible, use the primary/secondary piping
shown in Figures 20 or 21 on page 25. This piping de-
sign allows changing boiler flow rate without affecting
primary circuit flow rate.
If Figures 20 or 21 cannot be used, use the boiler-by-
pass piping shown in Figure 22 or Figure 23 on page 27.
Yo u  can also usethe piping shown in Figure 24 on
page 29 (system-bypass), if the reduced flow rate in
the heating system will not cause heat distribution
problems.
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.
Radiant heating systems
Preferably, use primary/secondary piping, as shown
in Figures 20 or 21 onpage25.Alternatively,usethe
method of either Figure 22 or Figure 23 on page 27.
Do not use the piping of Figure 24 (system-bypass),
because this method does not control radiant system
supply temperature.
If radiant system tubing has no oxygen barrier, a heat
exchanger
must be used.
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.
DO NOT apply the methods in this manual if the system is equipped with an outdoor 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.
Water piping — multiple zones