Carel Heos, User Manual

Page: 27 / 60

27
ENG
Heos +0300078EN - rel. 1.6 - 23.11.2017
When starting the defrost, the compressor is controlled at the defrost
speed (parameter dH2). The bypass valve (HGV) is activated, the fans
switch off and the expansion valve operates as normal. At the end of
the defrost, the HGV is deactivated, the dripping period elapses with
compressor operating at minimum capacity, the expansion valve
operating and the fans off . This is followed by the post-dripping stage,
with the compressor reactivated and the fans off . At the end of the post-
dripping stage, normal control resumes.
time
DEF
FAN
HGV
EEV
CMP
speed
Normal
reg.
Normal
reg.
Defrost state Drip Post drip
Min
Speed
Fig. 6.p
Key
CMP Compressor HGV Hot gas bypass valve
EEV Expansion valve Drip Dripping time
FAN Fan Post drip Post-dripping time
DEF Defrost
Defrost by reversing the cycle (d0 = 1, 3)
W aterloop
Fig. 6.q
When starting the defrost, the compressor decelerates to minimum
speed, and after a delay (dG5) the 4-way valve is activated.
After 5 seconds, the compressor accelerates to the defrost speed dG2,
until the defrost ends. After the time dG6 elapses, the 4-way valve is
deactivated and control resumes after a delay (dG7). During the defrost,
the expansion valve can be set to operate as normal or remain in a stable,
set position (parameters dG8, dG9, dG10)
Par. Description Def U.M. Min Max
dG2 Compressor speed (defrost by reversing the cycle) 50.0 rps cIc cIb
dG3 Maximum acceleration in defrost (reverse cycle) 1.0 rps cId cIE
dG4 Out of envelope alarm delay (defrost by reversing cycle) 600 s 0 999
dG5 4-way valve changeover delay on defrost 10 s 0 99
dG6 4-way valve changeover delay after defrost 10 s 0 99
dG7 End defrost delay (defrost by reversing cycle) 60 s 0 180
dG8
EEV mode at start defrost
1 -- 0 1
dG9
EEV mode during defrost
1 -- 0 1
dG10 EEV mode at end defrost 1 -- 0 1
time
DEF
FAN
4 WV
EEV
CMP
speed
Min Speed
Fixed Fixed
Min Speed
Defrost Speed
Fig. 6.r
Key
CMP Compressor
EEV
Expansion valve
FAN Fan
DEF Defrost
4WV Reversing valve
Maximum time between consecutive defrosts (parameter dI)
Parameter dI (screen Dca03) is a safety parameter used to perform cyclical
defrosts every “dI” hours, even without the Real Time Clock (RTC). It is also
useful if the pLAN or RS485 serial network is disconnected, when defrosts
are controlled by the supervisor. At the start of each defrost, irrespective
of the duration, an interval starts being counted. If this interval exceeds
dI without a defrost being performed, one is started automatically.
The count is always active even if the controller is OFF. If set on Master
controller, the parameter has eff ect on all the sub-LANs connected, if set
on a Slave controller, it only has an eff ect locally.
Par. Description Def U.M. Min Max
dI Interval between two consecutive defrosts 0=disabled 8 h 0 500
d4 Enable defrost at start-up
0: disabled (NO); 1: enabled (YES) 0 -- 0 1
d5 Defrost delay at start-up or from digital input 0 min 0 240
Defrost at start-up (parameter d4)
Defrost at start-up has priority over the control request. On the Master
controller the defrost at start-up will be a network defrost, while on the
Slave controllers it will be local.
Defrost delay at start-up (parameter d5)
Also active when d4=0. If the digital input is set to enable or start a defrost
via an external contact, parameter d5 represents the delay between
enabling or calling the defrost and when it eff ectively starts. In a Master/
Slave network, to activate the heater defrost via a digital input on the
Master, it is suggested to use parameter d5 to delay the various defrosts
on the Slaves, thus avoiding current overloads.
Example: if due to an RTC fault, the scheduled defrost (td3) is not
performed, after the safety time dI, a new defrost starts.
time
td1
DEF
ON
OFF
td2
td3
dl
Fig. 6.s
Key
dI Maximum time between consecutive defrosts DEF Defrost
td1…td3 Scheduled defrosts