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Service; Check-Out - Honeywell VC7900 Series Product Data

Modulating control valves
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In a direct acting model, 2 V signal will be fully closed, and 9 V will
be fully open. In a reverse acting model, 9 V is closed and 2 V is
open. However, because of the soft close off of the VC valve, initial
(and final) movements of the actuator will not cause any significant
changes in the valve stem position.
On a loss of power, the actuator will remain in the last position, and
will resume normal operation on power up. On loss of signal, a
direct acting device will go to the closed default position. A reverse
acting device will default open.


This valve should be serviced by a trained, experienced service
1. If the valve is leaking, drain system OR isolate valve from the
system. Do not remove valve body from plumbing.
2. Check to see if the cartridge needs to be replaced.
3. If the motor or other internal parts of the actuator is damaged,
replace the entire actuator assembly.
NOTE: Honeywell hydronic valves are designed and tested for
silent operation in properly designed and installed
systems. However, water noises may occur as a result
of excessive water velocity. Piping noises may also
occur in high temperature (over 212°F [100°C])
systems with insufficient water pressure.
Do not use boiler additives which are petroleum based
or contain mineral oil, hydrocarbons, or ethylene glycol
acetate. Compounds which can be used, with
minimum 50% water dilution, are diethylene glycol,
ethylene glycol, and propylene glycol(anti-freeze


1. Raise the set point of the thermostat above room temperature to
initiate a call for heat.
2. Observe all control devices - 2 way valve should open. Port A in
3 way valve should open, and port B should close.
3. Lower the set point of the thermostat below room temperature.
4. Observe the control devices. 2 way valve should close. Port A
in 3 way valve should close, and port B should open.
Home and Building Control
Honeywell Inc.
1985 Douglas Drive North
Golden Valley, MN 55422
Printed in Canada
In Canada:
Honeywell Limited–Limitée
155 Gordon Baker Road
North York, ON M2H 3N7
Helping You Control Your World

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