Weil-McLain GOLD CGS 550-110-260/02002 - Manual (Page 20)

Part number 550-110-260/0200
20
GOLD CGs Gas-Fired Water Boiler
Water piping — low temp systems
3e
This piping method is called a boiler-bypass because part of the circulator flow is bypassed
around the boiler (through valve 7a ). This method reduces the flow rate throughout the
boiler, in order to raise the average water temperature in the boiler enough to prevent flue gas
condensation. Boiler-bypass piping is effective for some boilers — including the CGs —
provided the flow rates are adjusted according to the instructions following.
Figures 10 and 11 are alternative piping suggestions for converted gravity (large water content
or steam systems) or radiant heating system — for use when primary/secondary piping
can’t be applied. ( Figure 12 is another alternative, using system bypass in place of boiler-
bypass piping. Figure 12 however, is not suitable for radiant heating applications because it
does not protect the radiant system from possible high water temperature.)
Boiler-bypass piping keeps system flow rate as high as possible and temperature drop as low
as possible, helping to equalize the building heat distribution.
Boiler-bypass piping
method
Temperature gauges
Gauge 4a is optional if the bypass valves will be adjusted using cold (or room temperature)
return water to the boiler. (When setting the valves without gauge 4a installed — using cold
or room temperature water — assume the return water temperature to be 60 °F. Set the valves
so gauge
8 reads at least 120 °F.
Gauge 4b is optional on converted gravity systems, but required on radiant heating systems
— to display the water temperature being supplied to the radiant tubing.
Gauge 8 is required on all systems to assure reliable adjustment of the bypass valves. The
boiler-mounted temperature/pressure gauge can be used if a separate temperature gauge is
not installed.
1. Start with valve 7a fully closed and 7b fully open.
2. Gradually open valve 7a while closing valve 7b until the temperature at gauge 8 reads
60 °F higher than gauge 4a . A minimum 60 °F temperature rise through the boiler assures
a low enough flow rate and high enough average temperature to prevent condensation
even with low system return water temperature.
3. Valve 7a regulates the system flow rate, while valve 7b regulates the boiler flow rate.
4. The boiler-mounted temperature/pressure gauge may be used in place of a separate
gauge 8 .
Valve adjustment
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 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 of 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.