Part number 550-110-260/0107
18
GOLD CGs Gas-Fired Water Boiler — Boiler Manual
Piping — low temp systems
3d
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
).
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 re-
turn 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.
Primary/secondary
(preferred)
bypass piping method
Primary/secondary
bypass 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 8
and
9
, page 19, show suggested bypass ar-
rangements using
primary/secondary
bypass piping
(preferred) for low temperature systems such as
radiant
heating systems
or
converted gravity systems
. For
alternatives, see pages 0 through 3.
The bypass valves in
Figures 8
and
9
(items
7a
and
7b
)
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
Gauge
4a
is suggested, but optional on any system.
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 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 8 and 9 only)
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).
. Start with valve
7a
fully closed and
7b
fully open.
3. Gradually open valve
7a
while closing valve
7b
until
the temperature at gauge
8
reads 130°F when gauge
4a
reads 60°F.
4. Note that valve
7a
regulates the amount of hot wa-
ter from the boiler supply which mixes with return
water. Valve
7b
regulates the amount of system water
flowing through the boiler secondary loop.
