Mitsubishi Electric QAHV-N560YA-HPB, Service Handbook

Page: 167 / 176

[
IX
Troubleshooting ]
- 160 -
HWE1517A GB
2. Detailed workflow: From determining the need for cleaning up to the completion of cleaning
Explained below are details of steps (1) through (6) in the previous page.
(1) Determining the need for cleaning
*Removal procedure for short pipe for checking the presence of scale
3 1
2
3
Photo 2: Short pipe for checking the
presence of scale Photo 3: Disassembled view of the short pipe for checking the
presence of scale
Disassembled
view
Fastener
(2) Preparation for cleaning
Photo 1: Location of the short pipe for checking the presence of scale
3
P
2
1 4
P
Heat pump unit
Figure 1 Cleaning device (inside the dashed lines)
2) The short pipe for checking the presence of scale
can be found (see Photo 1) when seen from
below the panel side of the machine room.
(The short pipe is gold and is located behind the
compressor.)
1) Shut off the power to the unit, close the valves at the hot water supply port, feed water port, and circulation water
inlet before proceeding to the next step. (See the outline diagram for the location of pipe connections.)
3) The short pipe is installed as shown in Photo 2. It can be disassembled into three components:
1
Short pipe,
2
fastener, and
3
gas cooler pipe.
To remove these components, first remove the saddle shown in Photo 1 from the top, pull up and out the fasteners
2
, and then remove the gas cooler pipes
3
that are connected to the short pipe
1
.
If the thickness of scale on the short pipe on the entire surface has exceeded 0.5 mm, perform cleaning.
Saddle
2
Items to prepare (Inside the dashed lines in Figure 1 is the cleaning
device.)
• Cleaning agent
• Sodium nitrate (neutralizing agent)
The use of solution type sodium nitrate is preferable. When using
the powder type, powder must be well dissolved.
•
1
Container (for cleaning)
Approximate holding capacity (three to four times the internal
volume of the circuit)
•
2
Pump (15 L/min; water head: 3 m minimum)
•
3
Submersible pump (placed in the container for exhaust water)
•
4
Container for placing exhaust water (Approximate holding
capacity: 100 L)
• pH tester
• Water pressure gauge (to measure approximate flow rate), if
available
• Water
*Internal gas cooler volume (the parts to be cleaned of scale):
Approximately 7 L
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