APEN0H-028CH33A0308
4
Fig.7–WiringColour Code for CableModels for 0-10Vdc
Controller (Series 70).
OPERATION
WITHSERIES70, 0/2-10VDCCONTROLLER
(refer to figure8)
In theVC7900, an electronic circuit compares the voltage of the
feedback potentiometer to the signal voltage. If they aredifferent, then
the circuit closes the appropriate triac and drives themotor in the
direction that will bring the circuit back intobalance. In addition, the
standard limit switchesmaintain the travel to thenormal operating range.
In a direct actingmodel, 2V signal will be fully closed, and9Vwill be fully
open. Ina reverse actingmodel, 9V is closedand 2V is open. However,
because of the soft close off of theVC valve, initial (and final)
movements
of theactuator will not cause any significant changes in the valve stem
position.
On a loss of power, the actuator will remain in the last position, andwill
resume normal operation onpower up. On loss of signal, adirect acting
devicewill go to the closed default position. A reverse acting devicewill
default open.
SERVICE
This valve should be serviced by a trained, experienced service
technician.
1. If the valve is leaking, drain system
OR
isolate valve from the system.
Do not remove valve body fromplumbing
.
2. Check to see if the cartridge needs tobe replaced.
3. If themotor 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 noisesmayoccur as a result of excessive
water velocity. Piping noisesmayalsooccur inhigh
temperature (over 212
˚F
[100
℃
]) systemswith insufficient
water pressure.
IMPORTANT
Do not use boiler additiveswhich are petroleum based
or containmineral oil, hydrocarbons, or ethylene glycol
acetate. Compoundswhich can be used, withminimum
50%water dilution, arediethylene glycol, ethylene glycol
and propylene glycol(anti-freeze solutions)
CHECK-OUT
1. Raise the set point of the thermostat above room temperature to
initiatea call for heat.
2. Observe all control devices - 2way valve should open. Port A in 3way
valve should open, andport B should close.
3. Lower the set point of the thermostat below room temperature.
4. Observe the control devices. 2way valve should close. Port A in3
way valve should close, and port B should open.
Automation andControl Solutions
Honeywell (Tianjin) Limited
No. 66, BaiHeRoad
TianjinEconomic-Technological Development Area
Tianjin, 300457, P.R.C.
Phone: +86-22-2532 0745
Fax:
+86-22-2532 5214
Subject to changewithout notice.
