Electric Reheat; Cooling System - Liebert DM User Manual

54 Chapter 6 System O&M

6.1.6 Electric Reheat

Check the rust on the electric reheat. If necessary, clean the dust with wire brush, or replace the heater.
The electric reheat is classified into upflow heater and downflow heater, as shown in Figure 6-5. Three temperature
switches are in series connection within the internal control circuit of the heater, including two auto-reset switches and
one manual reset switch. When the heater does not respond to the heating demand, check that the manual reset
switch is on.

6.1.7 Cooling System

Check the cooling system components once a month to make sure that the system function is normal and there are no
signs of wearing. Because the failure or damage of components is usually accompanied by corresponding faults,
regular checking is a major means to prevent most system faults. The refrigerant pipes must be supported by properly
set brackets, and be laid away from the ceiling, floor or anywhere that vibrates. Check the refrigerant pipes once every
six months to make sure that they are not worn out, and the fixing brackets are not loosened.
Each system has a sight glass to facilitate the observation of refrigerant flow and the system moisture content. When
the system moisture content is too high, the sight glass turns from green to yellow.
When the cooling system is faulty, you can locate the fault by referring to certain parameters of system operation.
Call for humidification
Note:
HMV: humidifier valve
IFS: Infrared small pan
IFL:Infrared large pan
Figure 6-4 Humidification control logic
Manual reset switch
Manual reset switch
Automatic reset switch
Upflow electric reheat
Figure 6-5 Upflow electric reheat and downflow electric reheat
DM Series 16kW Air Conditioner User Manual
On in last
No
15 hours?
Yes
HMV and
lamps on
4min: IFS
7min: IFL
Humidification
lamps only
8min: IFS
10min: IFL
Downflow electric reheat
HMV pre-fill
IFS: 30s
IFL: 60s
refill
110% ～ 500%
Automatic reset switch