Daikin RWEYQ144PCTJ, Installation Manual

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English 7
7. HANDLING OF THE BRAZED PLATE-
TYPE HEAT EXCHANGER
CAUTION
A brazed plate-type heat exchanger is used for this unit. Because
its structure is different from a conventional type heat exchanger, it
must be handled in a different manner.
7-1 When designing the equipment
1.
Install a strainer (50 mesh or more) at the water inlet side adjacent to
the outside unit in order to prevent any foreign materials such as
dust, sand, etc. from entering.
2.
Depending on the water quality, scale may stick to the plate-type
heat exchanger. In order to remove scale, it is necessary to use
chemicals to clean it at regular intervals. To this end, install a gate
valve in the water piping. Set up a piping connection port on the pip-
ing between this gate valve and the outside unit for cleaning by
chemicals.
3.
For the purpose of cleaning and water drain-off from the outside unit
(water draining during a long period of non-use in winter, draining
upon starting of season-off), install an “air discharge valve” and a
“water draining plug” at the inlet/outlet ports of water piping. In addi-
tion, install an “automatic air discharging valve” at the top of riser pip-
ing or at the top of a portion where air tends to stay.
4.
Independent of the piping inlet of the outside unit, install a cleanable
strainer at a portion close to the pump piping inlet.
5.
Carry out complete cooling/thermal insulation of water piping and
outdoor dehumidification. If complete cooling or thermal insulation
has not been carried out, any damage may be caused during severe
winter due to freezing, in addition to thermal loss.
6.
When you stop operation during night or winter, it is necessary to take
measures to prevent water-related circuits from natural freezing in the
area the ambient temperature drops below 32°F (0°C) (by water drain
off, keeping the circulation pump running, warming up by a heater,
etc.) Freezing of water related circuits may result in any damage to
the plate-type heat exchanger. Therefore, take appropriate measures
depending on the circumstances of use.
(Refer to figure 7)
1. Example of piping
2. Water inlet piping
3. Strainer
4. Air discharge valve (for joint use with cleaning port)
5. Cleaning device
6. Strainer for pump
7. Automatic air discharge valve
8. Water outlet piping
9. Joint use with water draining plug
10. Plate-type heat exchanger
11. Outside unit
7-2 Before starting a test run
1.
Before starting a test run, please make sure that the piping work has
been carried out in a proper manner. Especially, make sure that the
strainer, air discharge valve, automatic water supply valve, expansion
tank and cistern are positioned at their places correctly.
2.
After water has been completely filled in, first run the pump only, and
then make sure that no air has been caught in the water circulation
system and that the water flow rate is correct. If any air has been
caught or the flow rate is not enough, the plate-type heat exchanger
may freeze. Measure any water pressure loss before and after the
outside unit and make sure that the flow rate is as designed. In case
of any abnormality, stop the test run immediately and carry out trou-
ble shooting to resolve the trouble.
3.
Following the installation manual, carry out a test run of the outside
unit.
4.
After the test run has been completed, inspect the strainer at the inlet
piping of the outside unit. Clean it if it is dirty.
7-3 Daily service and maintenance
1.
Management of water quality
The plate-type heat exchanger has a structure that does not permit
dismantling and cleaning, or replacing any parts. Please pay attention
carefully to the quality of water to be used for the plate-type heat
exchanger in order to prevent corrosion and sticking of scale.
The water to be used for the plate-type heat exchanger should have at
least the quality as specified in the table below.
When using any corrosion prevention agent, scale depressant agent,
etc., such agent should have no corrosive features against stainless
steel and copper.
2.
Management of condenser water flow rate
If the condenser water flow rate is not enough, it will result in freezing
damage to the plate-type heat exchanger. Check for any clogging of
the strainer, any air being caught, any reduction in the flow rate due
to failure of the circulation pump by measuring the temperature and
pressure differences at the inlet and outlet ports of the plate-type
heat exchanger. If the aged difference in the temperature or pressure
has increased beyond the proper range, the flow rate should have
decreased. Stop the operation and remove the cause before restart-
ing the operation.
3.
Steps to be taken if a freeze-protection device is activated
If the freeze-protection device is activated during operation, be sure
to remove the cause before restarting the operation. If the freeze-pro-
tection device has been once activated, a partial freezing has already
occurred. If you restart the operation without removing the cause, the
plate-type heat exchanger will be closed and the ice cannot be
melted, and in addition, the freezing process will be repeated, result-
ing in any damage to the plate-type heat exchanger, and this can lead
to refrigerant leaking or water entering the refrigerant circuit.
7-4 Water quality
Water quality standards for condenser water, hot water and
makeup water (4) (6)
Item (5)
Cooling water system (3)
Hot water system (2) Tendency (1)
Circulation system
Circulation
water
Makeup
water
Circulation
water
(68 to 140°F
(20 to 60°C))
Makeup
water
Corrosion Scale
Standard items
pH (77°F (25°C))
6.5 to 8.2 6.0 to 8.0 7.0 to 8.0 7.0 to 8.0
{ {
Electrical Conductivity
(mS/ft. (mS/m))
(77°F (25°C))
Less than
24.4 (80)
Less than
9.1 (30)
Less than
9.1 (30)
Less than
9.1 (30)
{ {
Chloride ions
(mgcl
–
/L)
Less than
200
Less than
50
Less than
50
Less than
50
{
Sulfate ions
(mgSO
4
2-
/L)
Less than
200
Less than
50
Less than
50
Less than
50
{
Acid consumption
(pH4.8) (mgCaCO
3
/L)
Less than
100
Less than
50
Less than
50
Less than
50
{
Total hardness
(mgCaCO
3
/L)
Less than
200
Less than
70
Less than
70
Less than
70
{
Calcium hardness
(mgCaCO
3
/L)
Less than
150
Less than
50
Less than
50
Less than
50
{
Ionic-state silica
(mgSiO
2
/L)
Less than
50
Less than
30
Less than
30
Less than
30
{
Reference items
Iron (mgFe/L)
Less than
1.0
Less than
0.3
Less than
1.0
Less than
0.3
{ {
Copper (mgCu/L)
Less than
0.3
Less than
0.1
Less than
1.0
Less than
0.1
{
Sulfate ion
(mgS
2-
/L)
Shall not be
detected
Shall not be
detected
Shall not be
detected
Shall not be
detected
{
Ammonium ion
(mgNH
4
+
/L)
Less than
1.0
Less than
0.1
Less than
0.3
Less than
0.1
{
Residual chlorine
(mgCl/L)
Less than
0.3
Less than
0.3
Less than
0.25
Less than
0.3
{
Free carbon dioxide
(mgCO
2
/L)
Less than
4.0
Less than
4.0
Less than
0.4
Less than
4.0
{
Stability index
6.0 to 7.0 — — —
{ {
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