Weil-McLain CGA25SPDN Boiler User Manual


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GOLD CGa Gas-Fired Water Boiler — Boiler Manual
24
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.
Piping — low temperature systems (continued)
SYSTEM-bypass piping
method
This piping method (&IGURE, page 25) is called a SYS
TEMBYPASS
because part of the circulator flow bypasses
the system (through valve A). This bypassed hot water
from the boiler outlet mixes with cooler system return
water temperature in order to provide minimum 130°F
RETURNWATERTOTHEBOILER6ALVE
B will most often be
full open, but may need to be slightly closed on some
low pressure drop systems in order to cause enough
flow through valve
A.
&IGURE is an alternative piping method that provides
return water temperature control for boilers installed
on
CONVERTEDGRAVITYSYSTEMS (large water content
or steam systems).
$/./4
apply the piping of &IGURE  on RADIANT
HEATINGSYSTEMS
. It provides no method of regulat-
ing the water temperature provided to the system and
could result in excessive water temperature in the radi-
ant tubing.
System-bypass piping as shown in
&IGURE can be used
with either zone valve or circulator zoning. When used
with circulator zoning however, the boiler circulator
(item), must be piped as shown. It cannot be used as
one of the zoning circulators.
$/./4 apply system-bypass piping if the reduced
flow in the system could cause poor heat distribution.
That is, system-bypass piping reduces the flow in the
system and increases the water temperature 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
1. Start with valve A fully closed and B fully open.
 'RADUALLYOPENVALVE
A while closing valve B until
the temperature at gauge reads at least 130°F at all
times.
 6ALVE
A regulates the amount of boiler supply water
MIXEDWITHRETURNWATER6ALVE
Bcauses a pressure
drop in the system needed to balance flow through
valve A and the system.
4. The valve adjustment should be done with the
system at the coldest expected temperature (60°F
for converted gravity systems or high mass radiant
systems).
3d
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