DH-SMT/SI
VI.JA.G2.02
© Danfoss 11/2006
13
Instructions
Pilot-controlled PCVQ DN 100 - DN 250 (PN 16, PN 25)
8
Trouble Shooting
Fault
Possible cause
Remedy
Controller does
not hold the flow
rate on a
constant level
Throttle valve is open too widely.
Slightly close the throttle valve,
see section 7.10.
Air in the actuators
1. Loosen impulse tube connections at
the actuators by approx. 1 rotation.
2. Deaerate,
Caution hot water !
(move impulse tube until medium
penetrates).
3. Tighten impulse tube connections.
Impulse tubes or impulse tube
connections are dirty or damaged.
1. Remove impulse tube.
2. Clean impulse tubes and impulse
tube connections and check for free
passage.
Flow rate is too low
Valve plug of the pilot valve AVP-F
does not open:
Valve seat or plug is dirty or damaged, trim
is dirty.
1. Remove impulse tube.
2. Dismount actuator and trim.
Procedure, see section 9.4.
3. Clean seat and plug.
4. If damaged, replace trim or valve.
Valve plug of the pilot valve VFQ 21
does not open:
Valve seat or plug is dirty or damaged,
trim is dirty.
1. Remove impulse tube.
2. Dismount actutor and trim 1 ).
Procedure, see sections 9.1 and 9.2.
3. Clean seat and plug.
4. If damaged, replace trim or valve.
Rolling diaphragm in the actuator of the
valve unit is defective, i.e. valve VFQ 21
does not open.
1. Remove impulse tube.
2. Loosen union nut SW 46 and remove
actuator, see also section 9.1.
3. Replace actuator.
1)
The trim can be replaced by qualified personnel up to DN 125.
From DN 150 replacement should be carried out by the Danfoss service personnel.
