Weil-McLain CGA25SPDN Boiler User Manual


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GOLD CGa Gas-Fired Water Boiler — Boiler Manual
20
Part Number 550-101-009/0107
Failure to PREVENTLOWRETURNWATERTEMPERATURE to the boiler could cause corrosion 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
REGULATINGTHEBOILERRETURN
WATERTEMPERATURE
and the SYSTEMSUPPLYTEMPERATURE (such as provided by an INJEC
TIONPUMPINGCONTROL
).
"OILER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 of this manual if the system is equipped with an OUTDOOR
RESETCONTROL
Instead, PROVIDECONTROLSANDPIPING which can REGULATETHEBOILERRE
TURNWATERTEMPERATURE
at NOLESSTHAN& regardless of system supply temperature.
#ONTACTYOUR7EIL-C,AIN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.
Primary/secondary (preferred)
Bypass piping method
0RIMARYSECONDARYbypass piping is preferred because
the flow rate and temperature drop in the heating
circuit(s) is determined only by the heating circuit
circulator(s). So adjustment of the bypass valves in
the boiler circuit will not cause a change in the heating
circuit rate and temperature distribution.
Figures 13 and 14, page 21, show suggested bypass
arrangements using
PRIMARYSECONDARY bypass piping
(preferred) for low temperature systems such as RADIANT
HEATINGSYSTEMS
or CONVERTEDGRAVITYSYSTEMS. For
alternatives, see pages 22 through 25.
The bypass valves (items
A and B) provide mixing of
hot boiler outlet water with cooler system return water
— set to assure a minimum return water temperature
(at least 130°F) to the boiler. Set the valves as explained
below.
Temperature gauges
'AUGEA is suggested, but optional on any system.
'AUGE
B is optional on converted gravity systems,
but
REQUIREDon radiant heating systems — to display
3d
the water temperature being supplied to the radiant
tubing.
'AUGE
is REQUIREDon all systems to assure the return
water temperature is accurately set for a minimum of
130°F. If this gauge is not available however, adjust the
valves such that the boiler-mounted temperature/pres-
sure gauge reads at least 150°F when the system return
water is cold (approximately 60°F water temperature).
Valve adjustment
(Figures 13 and 14 on
ly)
1. Set the valves while the system is cool, setting for the
coldest expected water temperature (usually 60°F
since the system will often drop to room tempera-
ture between cycles).
2. Start with valve
A fully closed and B fully open.
 'RADUALLYOPENVALVE
A while closing valve B until
the temperature at gauge reads 130°F when gauge
A reads 60°F.
 .OTETHATVALVE
A regulates the amount of hot wa-
ter from the boiler supply which mixes with return
WATER6ALVEB regulates the amount of system water
flowing through the boiler secondary loop.
Piping — low temperature systems
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