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VGF FLANGED GLOBE VALVES
17
63-2618—01
Mixing Valve (Fig. 21)
• As the stem moves downward:
—
Flow from port B to AB decreases linearly.
—
Flow from port A to AB increases at an equal per-
centage rate.
• As the valve stem moves upward:
—
Flow from port B to AB increases.
—
Flow from port A to AB decreases.
NOTE:
The B port seat of the VGF3_EM valves is con-
structed as a cage, not as a seat, and moves
through the B port. It does not offer tight close-
off. For leakage specifications, see Table 4. B port
flow is at a minimum when stem travel down is
3/4 in. (20 mm) in 2-1/2 and 3 in. mixing valves.
OUTDOOR RESET CONTROL (FIG. 24)
• Connect the A port to a boiler output.
• Connect the B port to the system return.
AIR HANDLING APPLICATIONS (FIG. 23)
• Connect the A port to the output of a coil.
• Connect the B port to the coil bypass.
BOILER/CHILLER BYPASS (FIG. 25)
• VGF mixing valves are not recommended for boiler or
chiller bypass due to B port close-off ratings. Use
diverting model instead.
IMPORTANT
VGF Mixing Valves are assembled through the
lower (B) port. The B port stop collar (see Fig. 21)
holds the stem and plug assembly in the bonnet.
Ensure the stem remains raised while servicing
the valve or installing stem extensions. The stem
collar provides a hard stop for direct-acting
MP953 pneumatic actuators, and should not be
removed.
Note that the full stroke of the valve stem can be greater
than the control stroke dimension, Y, in Table 8, which is
measured from the closure of the A port. Honeywell
actuators are constructed for this Y dimension, and limit
stem travel appropriately.
DIVERTING VALVE (FIG. 22)
• As the valve stem moves downward:
—
Flow from port AB to A decreases linearly.
—
Flow from port AB to B increases linearly.
• As the valve stem moves upward:
—
Flow from port AB to A decreases.
—
Flow from port AB to B increases.
OUTDOOR RESET CONTROL (FIG. 25)
• Connect the A port to the building supply.
• Connect the B port to the boiler return.
AIR HANDLING APPLICATIONS (FIG. 26)
• Connect the A port to the coil supply.
• Connect the B port to the system return.
NOTE:
The A and B connections may be reversed when
using pneumatic actuators.
Fig. 21. VGF31EM mixing valve operation.
NOTE:
B port stop collar is shipped on VGF31EM25/30
and VGF32EM25/30 valves.
Fig. 22. VGF31LD diverting valve operation.
B PORT
STOP COLLAR
B PORT
AB PORT
A PORT
STEM
UP
M22410C
B PORT STOP COLLAR IS SHIPPED ON VGF31EM25/30
AND VGF32EM25/30 VALVES.
1
1
B PORT
AB PORT
A PORT
M36097
STEM
DOWN