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Maintenance and service
Installer and user reference guide
134
RWEYQ8~14T9Y1B
VRV IV water-cooled system air conditioner
4P452191-1B – 2020.10
22.2 Maintenance of the plate heat exchanger
The performance of a plate heat exchanger may decline due to scale accumulation.
It may be damaged by freezing due to the decrease in the flow rate. For this
reason, it is necessary to carry out programmed maintenance at regular intervals in
order to prevent scale.
At the beginning of the season, carry out following inspections:
▪
water quality test and follow the recommendations as described in
▪
clean the water filter,
▪
water flow rate is correct,
▪
operational conditions (e.g. pressure, water flow rate, outlet temperature,…) are
normal.
22.2.1 To clean the plate heat exchanger
Disassembling and cleaning of the plate heat exchanger is not possible. Please use
following steps.
Prerequisite:
Provide a connection port on the water inlet and on the water outlet
and connect a circulation pump in between these 2 connection ports when
cleaning with chemicals.
Prerequisite:
Provide a stop valve in front of the inlet water pipe connection port
and a stop valve after the outlet water connection port.
Prerequisite:
Use a solution with 5% diluted formic, citric, oxalic, acetic or
phosphoric acid for cleaning scale. NEVER use hydrochloric, sulphuric or nitric acid
because such solutions have a strong corrosive feature.
1
Connect the piping for circulation of cleaning chemicals to the inlet piping of
the plate heat exchanger.
2
Fill a cleaning solution of 50°C~60°C for a while in the plate heat exchanger.
3
Circulate for 2~5 hours by using a pump. Time for cleaning depends on the
temperature of the cleaning solution or the degree of scale accumulation.
Therefore, please watch the change of dirtiness of the cleaning solution to
determine the level of removal of scale.
4
After circulating the cleaning solution, discharge the solution from the plate
heat exchanger.
5
Fill the plate heat exchanger with a solution of 1-2% sodium hydroxide (NaOH)
or sodium bicarbonate (NaHCO
3
).
6
Circulate this solution for 15-20 minutes for neutralization purpose.
7
Rinse the inside of the plate heat exchanger with care using fresh and clean
water.
8
When using any commercially available cleaning agent, check in advance that
such agent has no corrosive features against stainless steel and copper. Ask
the manufacturer of the cleaning agent for more details.
9
Check if the unit can operate in a normal way.