Bryant 246 - Water Controls

F. 011/018
SEP/04/2008/THU 09:17 AM UTC TECH PUB
FAX Ho. 317 240 5662
Water Controls
The water controls for the boiler consist of three com¬
ponents:
1- Water temperature high-limit control (electric).
2, Combination temperature-pressure-altitude gauge.
3, Pressure relief valve (must be piped to suitable
drain).
Install temperature-pressure-altitude gauge in the
tapping indicated in Figure 13. Remove the glass
cover of the gauge and manually set inner pointer to
indicate the vertical height from the gauge to the
highest point in the piping system.
Boiler with Refrigeration System
When the boiler is used in connection with a
refrigeration system, it must be installed so that the
chilled medium is piped in parallel with the heating
boiler, with appropriate valves to prevent the chilled
medium from entering the heating boiler. An example
of such piping is shown in Figure 24.
When the boiler is connected to heating coils located
in air handling units where they may be exposed to
refrigerated air circulation, the boiler piping system
must be equipped with flow Control valves or other
automatic means to prevent gravity circulation of the
boiler water during the cooling cycle.
Note: It is recommended that a relief valve be in¬
stalled between valve A and the boiler or valve B and
the boiler. This relief valve will protect the boiler
from expansion pressures during the cooling season.
COMBINATION PRESSURE/
.VACUUM GAUGE
VALVES A h B — OPEN FOR HEATiNd close r'Gn COOLING
V StlG^PRESSURE
LIMIT.
^ ' LOW-WATER
CUTOFF
Figure 23 - Steam Controls
AB6457
Figure 24 - Refrigerant Diagram
D4 Gas Controls
732 Automatic Pilot:
The pilot assembly includes a normally open switch
wired in series with the Bryant automatic gas control
valve. The switch is at the free end of the monometal
element, assembled so that the fixed end is' positioned
at the pilot flame..Heat applied to the fixed end of the
monometal element causes the free end to move. This
closes the switch and completes the electrical circuit
to the control valve. The circuit will close within one
minute. It will remain closed as long as there is nor¬
mal pilot flame. While closed, the boiler is under the
direct automatic control of the room thermostat or
other operating control as long as the main manual
gas shutoff valve is open. If the pilot flame goes out
for any reason, the monometal element will cool and
the free end will move back to its original position.
This breaks the electric circuit and the. Bryant
automatic, gas control valve will close. This shuts off
tire gas supply to the main burner. ;
Bryant Automatic Gas Control Valve:
The Bryant gas control valve operates on the prin¬
ciple of differential pressure on either. side of a
flexible diaphragm which divides the main body -of
the valve into two compartments. The lower compart
ment is under constant-pressure fromrthe‘'gasisuppJy“
line. Gas pressure to the upper compartment is con¬
trolled by a small valve actuated by. an electric heat
motor.. The control valve allows gas to flow to or from
the upper compartment 'V * /
The electric heat motor is connected into the 24-Volt
control circuit with the room thermostat or other
boiler operating controls. When there is a call for
heat, the control valve closes the supply port to the
upper, compartment and allows the gas above the
diaphragm to bleed off through an escapement to the
pilot
The supply pressure on the bottom then pushes the
diaphragm up and gas flows to the main burners.