Changeover Between Cooling And Heating Cycle; Heating To Cooling; Service Operation; Purging - Hyundai HDFN-80-1400 Operation Instructions Manual

5.6 Changeover between Cooling and Heating Cycle.

5.6.1 Cooling to heating
Perform dilute operation to equalize the solution concentration and change the cycle.
(1) Change the selection switch in the control panel to heating from cooling.
(Snap switch – SW-4)
(2) Operate the cooling-heating change-over valves:
V7 : Open (adjustment is required.)
V12 : Open (adjustment is required.)
(3) Drain the cooling water in both the absorber and condenser completely and keep dry.
(4) Start-up the heating operation following the instruction in the 5.5.1 Start-up.

5.6.2 Heating to cooling

(1) Change the selection switch in the control panel to cooling from heating.
(Snap switch – SW-4)
(2) Operate the cooling-heating change-over valves:
V7 : Close
V12 : Close
(3) Start-up the cooling operation following the instruction in the 5.4.1 Start-up.

5.7 Service Operation

"Service operation" means that only the solution pump is operated manually by
controlling the service switch in the control panel.
Such operation is performed in the following cases:
(1) In the case that the solution level in the high pressure generator is low at starting.
The service operation pump up the solution to the high pressure generator to provide the
condition suitable for start-up.
(2) In the case that crystallization of solution occurs during cooling operation.
It can be de-crystallized by parallel operation of the service operation. If the service
operation can not be performed because the crystallization spreads over the solution pump,
other way for de-crystallization will be taken.
(3) In the case that re-generation of the refrigerant is required.
When the volume of re-generated refrigerant is less and the refrigerant pump makes noise
due to cavitation even at good condition for refrigerant pump start-up, the refrigerant can
be re-generated by service operation to stop the cavitation a few minutes which will bring a
normal operation.
6.

Purging

6.1 Importance of Purging

Water as refrigerant and lithium bromide solution as absorbent are charged in the gas/oil direct-fired
absorption chiller-heater. The lower the refrigerant pressure, at the lower temperature the
refrigerant evaporates. Therefore, the chiller-heater shall be kept in high vacuum. Generally, if non-
condensing gas such as hydrogen gas, air, etc. stays inside the chiller-heater, the following
phenomena may be considered to happen:
40