ECKELMANN UA 400 - Discharge Gas Defrosting (Hot Gas Defrosting)

Firmware V3.15
21.04.2021
38/401
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5.5.3 Discharge gas defrosting (hot gas defrosting)
Discharge gas defrosting involves feeding discharge gas into the evaporator and can be performed with either
hotorcoldgas.
The discharge gas is supplied from a point upstream of the condenser (hot gas defrosting) or from the receiver
downstreamofthecondenser(coldgasdefrosting).
These notes apply to two-pipe discharge gas defrosting. In doing so, the defrost relays are used for the
actuation of special solenoid valves for the discharge gas defrosting. In discharge gas defrosting allowance is
made for the specific properties of the discharge gas:
Demand defrost counter ignored on initiation of defrosting
No internal initiation of defrosting
No interruption of defrosting in occurrence of temperature alarm
Discharge gas defrosting requires a pack controller in the system. Case controllers which participate in the
hotgasdefrostingmustbeassignedtoapackcontrollerusingtheparameterRefr.Sys.No.. The
parameterRefr.Sys.TypemustalsobesetforVS3010BSpackcontrollers.Nofurtherparametershaveto
be set here.
Activating discharge gas defrosting on UR 141 TK (LT):
Discharge gas defrosting is always active on the UR 141 TK (LT) and does not require any further parameter
setting.
Termination of discharge gas defrosting on UA 131 DD:
Defrosting is terminated by the defrost termination temperature sensors at the earliest 4 minutes after defrost
initiation.
Termination of discharge gas defrosting on UR 141 TK (LT):
Defrosting is terminated by the defrost termination temperature sensors without delay. If an internal defrost
timer is set on the UA 141 TK (LT), it will be changed automatically to external defrosting by the pack controller
the first time discharge gas defrosting is initiated. This prevents the case controller from automatically initiating
defrosting.
Compressor damage!
Danger due to liquid refrigerant on the suction side of the compressor!Dischargegasdefrosting
as described herein is D2D two-pipe discharge defrosting, which can be performed only with hot gas.
Notes on discharge gas defrosting (controller type UA 131 DD, UR 141 TK (LT))

Compressor damage!Danger due to liquid refrigerant on the suction side of the
compressor!DuringthefirststartoftheUA131adefrostingisinitiatedimmediatelyfollowingthe
start. If the installation is not secured with suitable pack controller control lines for initiating the
discharge gas defrosting, liquid refrigerant can e.g. enter the suction hose. Therefore care must be
taken with applications with discharge gas defrosting that the manual defrost is deactivated following
the start of the controller and that the defrost timer is set to external defrost. Alternatively, i.e. in
addition, the activation of the regulator control elements specific to the discharge gas can be secured
using suitable control lines, e.g. from the pack controller.

Discharge gas defrosting cannot be used together with the master-slave function. With discharge gas
defrosting the operation must be terminated when the CAN bus defrost command ends. With master-
slavedefrostingtheoperationwouldnormallycontinueuntilthesafedefrosttimeexpires.
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