Mark MISTRAL MDX 33 User manual

MARK MISTRAL MDX 33 0662060
Technical manual EN

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EN
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READ THIS DOCUMENT BEFORE
INSTALLING THE HEATER
Warning
Incorrect installation, adjustment, alteration, repair or maintenance work may
lead to material damage or injury. All work must be carried out by certified,
qualified professionals. If the appliance is not positioned in accordance with the
instructions, the warranty shall be rendered void. This appliance is not intended
for use by children or persons with a physical, sensory or mental handicap, or
who lack the required experience or expertise, unless they are supervised or have
been instructed in the use of the appliance by somebody who is responsible for
their safety. Children must be supervised to ensure that they do not play with the
appliance.
1 General
1.1 Application
Appliance type MISTRAL MDX 33 is solely suitable for the free and direct intake of the
air to be heated and the free discharge of heated air into the room. If areas are to be
heated in which corrosive vapours are present (chlorinated hydrocarbons in particular),
which are either produced directly in the area, or which may be drawn in from the
outside by the heater via a duct or an open connection, wall air heaters cannot be used
because of the risk of corrosion to the heat exchanger.
Subject to change
The manufacturer is committed to constantly improving its products and reserves
the right to make changes in the specifications without prior notice. The technical
details are considered correct but do not form the basis for a contract or warranty. All
orders are accepted according to the standard terms of our general sales and delivery
conditions (available upon request). The information in this document is subject to
change without notice. The most recent version of this manual is always available at
www.markclimate.com/downloads.
1.2 General warnings
Incorrect installation, adjustment, alteration, maintenance or repair of the MISTRAL
MDX may lead to material or environmental damage and/or injuries. The appliance
should therefore be installed, adapted or converted by a skilled and qualified installer,
taking into account national and international regulations. Faulty installation,
adjustment, alteration, maintenance activity or repair shall render the warranty void.

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2 Technical specifications
2.1 Technical specifications
coolingheating
Type MDX 33
Power HP 12
Nominal capacity 1kW 33,5
Absorbed power 1kW 15,3
EER 12,19
Nominal capacity 2kW 37,5
Absorbed power 2kW 9,08
Nominal capacity 3kW 30,7
Absorbed power 3kW 10,79
SCOP 4,05
Electrical data
Power supply Ph/V/Hz 3/380-415/50
Maximum current A 19,60
Fuse A 32
Refrigerant features
Refrigerant R410A
Quantity refrigerant pre-load4kg 8
DC Inverter compressor no. / type 1 / Rotary DC Inverter
Pipe connections Liquid inch 1/2”
Gas Ø mm 28
Distance indoor and outdoor unit min m 2
max m 90
Max height difference m 40
Specifications outdoor unit
Dimensions (LxHxD) mm 1120x1558x528
Net weight kg 157
Sound pressure level (5 mtr.) max dB(A) 47
Air flow max m3/h 11300
Operating limits (outside temperature) Cooling °C -5 ~ +48
Heating °C -20 ~ +24
1 Indoor air temperature 27°C DB, 19°C WB; outdoor air temperature 35°C DB; equivelant refrigerant piping length 7.5m with zero level difference.
2 Indoor air temperature 20°C DB, 19°C WB; outdoor air temperature 7°C DB, 6°C WB; equivelant refrigerant piping length 7.5m with zero level
difference.
3 Indoor air temperature 16°C DB, 19°C WB; outdoor air temperature -19,8°C DB, -20°C WB; equivelant refrigerant piping length 7.5m with zero
level difference.
4 Excl. refill liquid pipe

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2.2 Heating capacities
Outdoor air
temp.
Indoor air temp. ºC DB
≤ 16 18 20 21 22 24
TC PI TC PI TC PI TC PI TC PI TC PI
ºC DB ºC WB kW kW kW kW kW kW kW kW kW kW kW kW
-19.8 -20 30.71 10.79 30.60 10.91 30.48 11.03 30.48 11.09 30.48 11.16 30.36 11.29
-18.8 -19 31.19 10.82 31.07 10.94 30.96 11.05 30.95 11.11 30.95 11.17 30.83 11.30
-16.7 -17 31.67 10.83 31.55 10.95 31.55 11.07 31.43 11.13 31.43 11.20 31.31 11.07
-13.7 -15 32.14 10.86 32.02 10.96 32.02 11.09 31.90 11.15 31.90 11.21 31.79 10.84
-11.8 -13 32.62 10.87 32.50 10.99 32.50 11.11 32.38 11.17 32.38 11.22 31.79 10.63
-9.8 -11 32.86 10.88 32.86 11.00 32.74 11.12 32.74 11.17 32.62 11.24 31.79 10.53
-9.5 -10 33.10 10.90 32.98 11.00 32.98 11.12 32.86 11.19 32.86 11.25 31.79 10.44
-8.5 -9.1 33.45 10.91 33.45 11.01 33.33 11.13 33.21 11.20 33.21 11.26 31.79 10.29
-7 -7.6 36.07 10.92 35.95 11.02 35.95 11.14 35.83 11.61 34.64 11.04 31.79 9.96
-5 -5.6 36.55 10.94 36.43 11.03 36.43 11.14 36.07 12.00 34.64 11.42 31.79 10.30
-3 -3.7 37.26 10.95 37.14 11.03 37.14 10.78 36.07 11.29 34.64 12.00 31.79 10.83
0-0.7 38.21 10.96 40.36 11.04 37.50 10.48 36.07 11.87 34.64 11.32 31.79 10.17
32.2 40.71 11.65 40.36 10.76 37.50 10.18 36.07 10.92 34.64 10.42 31.79 9.42
54.1 43.21 11.05 40.36 10.24 37.50 9.70 36.07 9.97 34.64 9.53 31.79 8.67
7 6 43.21 10.44 40.36 9.71 37.50 9.08 36.07 8.72 34.64 8.36 31.79 7.66
97.9 43.21 9.84 40.36 9.20 37.50 8.55 36.07 8.24 34.64 7.92 31.79 7.30
11 9.8 43.21 9.21 40.36 8.63 37.50 8.08 36.07 7.80 34.64 7.53 31.79 6.99
13 11.8 43.21 8.63 40.36 8.15 37.50 7.66 36.07 7.42 34.64 7.19 31.79 6.71
15 13.7 43.21 8.21 40.36 7.79 37.50 7.36 78.93 7.15 34.64 6.94 31.79 6.51
Correction factor for frost accumulation
Heat exchanger inlet port temperature (C / RH 85%) -7 -5 -2 0 2 5 7
Correction factor for frost accumulation 0.94 0.93 0.89 0.84 0.83 0.91 1.00
2.3 Cooling capacities
Outdoor
temp.
(ºC DB)
Indoor temp. (ºC DB/WB)
DB:20.8; WB:14 DB:23.3; WB:16 DB:25.8; WB:18 DB:27; WB:19 DB:28.2; WB:20 DB: 30.7; WB:22 DB:32; WB:24
TC PI TC PI TC PI TC PI TC PI TC PI TC PI
kW kW kW kW kW kW kW kW kW kW kW kW kW kW
-5 23.50 5.48 27.59 5.97 33.03 6.58 33.50 7.72 36.32 7.54 41.75 8.35 43.02 9.21
-2 23.50 5.55 27.59 6.04 33.03 6.71 33.50 7.78 36.32 7.65 41.75 8.46 43.02 9.27
0 23.50 5.62 27.59 6.12 33.03 6.83 33.50 7.90 36.32 7.73 41.75 8.61 4302 9.38
2 23.50 5.70 27.59 6.20 33.03 6.98 33.50 7.97 36.32 7.82 41.75 8.75 43.02 9.53
4 23.50 5.75 27.59 6.30 33.03 7.07 33.50 8.09 36.32 7.93 41.75 8.84 43.02 9.64
6 23.50 5.88 27.59 6.40 33.03 7.19 33.50 8.27 36.32 8.05 41.75 8.98 43.02 9.79
8 23.50 5.97 27.59 6.53 33.03 7.33 33.50 8.41 36.32 8.19 41.75 9.13 43.02 9.96
10 23.50 6.09 27.59 6.65 33.03 7.44 33.50 8.54 36.32 8.35 41.75 9.30 43.02 10.11
12 23.50 6.21 27.59 6.79 33.03 7.72 33.50 8.71 36.32 8.51 41.75 9.48 42.42 10.19
14 23.50 6.33 27.59 6.94 33.03 8.08 33.50 9.27 36.32 8.68 41.75 9.69 41.95 10.32
16 23.50 6.46 27.59 7.10 33.03 8.28 33.50 9.50 36.32 8.86 40.51 9.81 41.35 10.44
18 23.50 6.58 27.59 7.25 33.03 8.60 33.50 9.88 36.32 9.05 40.03 10.16 40.87 10.71
20 23.50 6.73 27.59 7.50 33.03 9.31 33.50 10.55 36.32 9.73 39.43 10.68 40.27 11.24
21 23.50 6.79 27.59 7.80 33.03 9.98 33.50 11.19 36.32 10.08 39.20 10.95 40.03 11.51
23 23.50 7.26 27.59 8.42 33.03 10.73 33.50 11.96 36.32 10.84 38.72 11.48 39.43 12.05
25 23.50 7.78 27.59 9.08 33.03 11.58 33.50 12.56 36.32 11.64 38.12 12.02 38.95 12.58
27 23.50 8.31 27.59 9.76 33.03 12.26 33.50 13.32 36.32 12.49 37.52 12.56 38.36 13.14
29 23.50 8.89 27.59 10.49 33.03 13.19 33.50 13.71 36.20 13.29 37.04 13.57 37.88 13.67
31 23.50 9.51 27.59 11.25 33.03 14.10 33.50 13.96 35.72 13.83 36.44 14.06 37.28 14.23
33 23.50 10.15 27.59 12.05 33.03 14.77 33.50 14.36 35.13 14.37 35.97 14.58 36.80 14.79
35 23.50 10.81 27.59 12.92 33.03 15.07 33.50 15.30 34.53 15.32 35.37 15.48 36.20 15.63
37 23.50 11.53 27.59 13.83 33.03 15.18 33.07 16.00 34.18 16.22 34.89 16.43 35.61 16.65
39 23.50 12.27 27.59 14.77 33.03 15.45 32.65 16.62 33.72 16.90 34.29 17.24 35.13 17.38
41 23.50 12.73 27.59 15.36 33.03 15.68 32.23 17.21 33.25 17.57 33.04 17.73 34.63 17.92
43 23.50 13.19 27.59 15.65 33.03 16.21 32.12 18.03 32.78 18.32 33.23 18.63 33.36 18.77
45 23.50 13.80 27.59 16.08 33.03 17.22 31.91 19.18 32.32 20.24 32.95 21.25 32.82 21.66
48 23.50 15.91 27.59 17.14 33.03 18.36 31.54 20.66 31.85 21.88 32.20 23.10 32.33 24.33
CR: Combination ratio
TC: Total capacity (kW)
PI: Power input (compressor + outdoor fan motor (kW))

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3 Unit Placement and Installation
3.1 Acceptance and unpacking
»When units are delivered check whether any damage occurred during shipment.
If there is damage to the surface or outside of a unit, submit a written report to the
shipping company.
»Check that the model, specifications and quantity of the units delivered are as
ordered.
»Check that all accessories ordered have been included. Retain the technical manual
for future reference.
3.1.1 Hoisting
»Do not remove any packaging before hoisting. If units are not packaged or if the
packaging is damaged, use suitable boards or packing material to protect the units
units.
»Hoist one unit at a time, using two ropes to ensure stability.
»Keep units upright during hoisting , ensur ing that the angle to the vertical does
not exceed 30°.
3.2 Placement
3.2.1 Placement considerations
Placement of outdoor units should take account of the following considerations:
»Air conditioners should not be exposed to direct radiation from a high-temperature
heat source.
»Air conditioners should not be installed in positions where dust or dirt may affect
heat exchangers.
»Air conditioners should not be installed in locations where exposure to oil or to
corrosive or harmful gases, such as acidic or alkaline gases, may occur.
»Air conditioners should not be installed in locations where exposure to salinity may
occur unless the anti-corrosion treatment for high-salinity areas customization
option has been added and the precautions described in Chapter 10 “Installation in
Areas of High Salinity” are taken.
»Outdoor units should be installed in well-drained, well-ventilated positions that are
as close as possible to the indoor units.
3.2.2 Spacing
Outdoor units must be spaced such that sufficient air may flow through each unit.
Sufficient airflow across heat exchangers is essential for outdoor units to function
properly. Figures 3.1 to 3.5 show spacing requirements in three different scenarios.

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Figure 3.1 Single unit installation (unit: mm)
Figure 3.2 Parallel connect the two units or above (unit: mm)
Figure 3.3 Parallel connect the front with rear sides (unit: mm)
3.2.3 Base structures
Outdoor unit base structure design should take account of the following considerations:
»A solid base prevents excess vibration and noise. Outdoor unit bases should be
constructed on solid ground or on structures of sufficient strength to support the
units’ weight.
»Bases should be at least 200mm high to provide sufficient access for installation
of piping.
»Either steel or concrete bases may be suitable.
»A typical concrete base design is shown in Figure 3.4. A typical concrete specification
is 1 part cement, 2 parts sand and 6 parts crushed stone with Ø10mm steel reinforcing
bar. The edges of the base should be chamfered.
»To ensure that all contact points are equally secure, bases should be completely
level. Base design should ensure that the points on the units’ bases designed for
weight-bearing support are fully supported. Bolt spacings should be as per Figure
3.5.

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»A drainage ditch should be provided to allow drainage of condensate that may form
on the heat exchangers when the units are running in heating mode. The drainage
should ensure that condensate is directed away from roadways and footpaths,
especially in locations where the climate is such that condensate may freeze.
Figure 3.4 Outdoor unit typical concrete base structure design (unit: mm)
Figure 3.5 Expansion bolt positioning and space(unit: mm)
3.2.4 Centralized drainage
When centralized drainage is required, install two waterproof covers for the chassis, as
shown in Figure 3.6. Install the water outlet union pipe and sealing ring on the chassis,
and then connect the drainage pipe to complete centralized drainage installation.
Figure 3.6 Centralized drainage
3.3 Indoor units
For placement of indoor units please see the technical manual of the indoor unit
Mistral MDX.

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4 Refrigerant Piping Design
4.1 Design Considerations
Refrigerant piping design should take account of the following considerations:
»The amount of brazing required should be kept to a minimum.
»On the two inside sides of the first indoor branch joint the system should, as far
as possible, be equal in terms of number of units, total capacities and total piping
lengths.
4.2 Material Specification
Only seamless phosphorus-deoxidized copper piping that complies with all applicable
legislation should be used. Temper grades and minimum thicknesses for different
diameters of piping are specified in the tables on the next page.
Piping outer
diameter (mm)
Temper1Minimum
thickness (mm)
Ø 6.35
O (annealed)
0.8
Ø 9.53 0.8
Ø 12.7 0.8
Ø 15.9 1.0
Ø 19.1 1.0
Ø 22.2
1/2H
(half hard)
1.2
Ø 25.4 1.2
Ø 28.6 1.3
Ø 31.8 1.5
Ø 38.1 1.5
Ø 41.3 1.5
Ø 44.5 1.5
Ø 54.0 1.8
1 O: coiled piping; 1/2H: straight piping
4.3 Permitted Piping Lengths and Level Differences
The piping length and level difference requirements that apply are summarized in the
table above and are fully described as follows:
»The total length of piping in one refrigerant system should not exceed 50m.
»The largest level difference between indoor unit and outdoor unit should not
exceed 40m (if the outdoor unit is above) or 40m (if the outdoor unit is below).
Additionally: If the outdoor unit is above and the level difference is greater than
20m, it is recommended that an oil return bend is set every 10m in the gas pipe of
the main pipe.
When the outdoor unit connects to one indoor unit, the piping length and level

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difference requirements that apply are summarized in the tables below.
The max height drop (m) The length of
refrigerant pipe (m)
The number
of bends
Outdoor unit is above Outdoor unit is below
40 40 max 90 / min 2 ≤ 10
Equivalent lenght of all liquid pipes
and gas pipes < 90 m
Equivalent lenght of all liquid pipes
and gas pipes > 90 m
Gas pipe (mm) Liquid pipe (mm) Gas pipe (mm) Liquid pipe (mm)
Ø 28 Ø 12.7 Ø 28 Ø 12.7
4.4 Refrigerant Leakage Precautions
R410A refrigerant is not flammable in air at temperatures up to 100°C at atmospheric
pressure and is generally considered a safe substance to use in air conditioning systems.
Nevertheless, precautions should be taken to avoid danger to life in the unlikely event
of a major refrigerant leakage. Precautions should be taken in accordance with all
applicable legislation. Where no applicable legislation exists, the following may be
used as a guide:
»Air conditioned rooms should be large enough that if leakage of all the refrigerant
in the system occurs, the concentration of the refrigerant in the room does not
reach a level dangerous to health.
»A critical concentration (at which point R410A becomes dangerous to human
health) of 0.3 kg/m3can be used.
»The potential concentration of refrigerant in a room following a leak can be
calculated as follows:
- Calculate the total amount in of refrigerant in the system (“A”) as the
nameplate charge (the charge in the system when delivered from the factory)
plus the additional charge added as per Part 8.1 “Calculating Additional
Refrigerant Charge”.
- Calculate the potential refrigerant concentration as A divided by B.
- If A/B is not less than 0.3 kg/m3, counter measures such installing mechanical
ventilators (either ventilating regularly or controlled by refrigerant leakage
detectors) should be taken.
»Since R410A is heavier than air, particular consideration should be given to leak
scenarios in basement rooms.

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Figure 4.1 Potential refrigerant leak scenario
MISTRAL MDX
outdoor unit
MISTRAL MDX
indoorunit
Figure 4.2 Mechanical ventilator controlled by refrigerant leak detector
OUTSIDE AIR
AIR VENT
LEAKAGE DETECTOR
CONNECTED TO MECHANICAL
VENTILATOR
5 Refrigerant Piping Installation
5.1 Procedure and Principles
5.1.1 Installation procedure
Installation of the refrigerant piping system should proceed in the following order:
Note: Pipe flushing should be performed once the brazed connections have been
completed with the exception of the final connections to the indoor units. That
is, flushing should be performed once the outdoor unit have been connected but
before the indoor units are connected.
Pipe
insulation
Pipe brazing and
installation
Pipe
flushing
Gastightness
test
Joint
insulation
Vacuum
drying

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5.1.2 Three principles for refrigerant piping
Reasons Measures
CLEAN
Particles such as oxide produced
during brazing and/or building
dust can lead to compressor
malfunction
»Seal piping during storage1
»Flow nitrogen during brazing2
»Pipe flushing3
DRY
Moisture can lead to ice formation
or oxidization of internal
components leading to abnormal
operation or compressor damage
»Pipe flushing3
»Vacuum drying4
SEALED
Imperfect seals can lead to
refrigerant leakage
»Pipe manipulation5 and brazing2
techniques
»Gas tightness test6
Notes:
1See 5.2.1 “Pipe delivery, storage and sealing”.
2See 5.5 “Brazing”.
See 5.6 “Pipe Flushing”.
4See 5.8 “Vacuum Drying”.
5See 5.3 “Manipulating Copper Piping”.
6See 5.7 “Gas tightness Test”.
5.2 Storing Copper Piping
5.2.1 Pipe delivery, storage and sealing
»Ensure that piping does not get bent or deformed during delivery or whilst stored
stored.
»On construction sites store piping in a designated location.
»To prevent dust or moisture entering, piping should be kept sealed whilst in storage
and until it is about to be connected. If piping is to be used soon, seal the openings
with plugs or adhesive tape. If piping is to be stored for a long time, charge the
piping with nitrogen at 0.2 0.2-0.5MPa and seal the openings by brazing.
»Storing piping directly on the ground risks dust or water ingress. Wooden support
supports can be used to raise piping off the ground.
»During installation, ensure that piping to be inserted through a hole in a wall is
sealed to ensure dust and/ or fragments of wall do not enter.
»Be sure to seal piping being installed outdoors (especially if being installed vertically)
to prevent rain entering.
5.3 Manipulating Copper Piping
5.3.1 De-oiling
»Lubrication oil used during some copper pipe manufacturing processes can cause
deposits to form in R410A refrigerant systems, causing system errors. Oil-free copper
piping should therefore be selected. If ordinary (oily) copper piping is used, it must
be cleaned with gauze dipped in tetrachloroethylene solution prior to installation.
»CAUTION! Never use carbon tetrachloride (CCl4) for pipe cleansing or flushing, as
doing so will seriously damage the system.

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5.3.2 Cutting copper piping and removing burrs
»Use a pipe cutter rather than a saw or cutting machine to cut piping. Rotate the
piping evenly and slowly, applying even force to ensure that the piping does not
become deformed during cutting. Using a saw or cutting machine to cut piping
runs the risk of copper shavings entering the piping. Copper shavings are difficult
to remove and pose a serious risk to the system if they enter the compressor or
block the throttling unit unit.
»After cutting using a pipe cutter, use a reamer/scraper to remove any burrs that
have formed at the opening, keeping the opening of the piping downwards to
avoid copper shavings from entering the piping.
»Remove burrs carefully to avoid scratches , which may prevent a proper seal being
formed and lead to refrigerant leakage.
5.3.3 Expanding copper piping ends
»Ends of copper piping can be expanded so that another length of piping can be
inserted and the joint brazed.
»Insert the expanding head of the pipe expander into the pipe. After completing
pipe expansion, rotate the copper pipe a few degrees to rectify the straight line
mark left by the expanding head.
»CAUTION! Ensure that the expanded section of piping is smooth and even. Remove
any burrs that remain after cutting.
Figure 5.1 Mechanical ventilator controlled by refrigerant leak detector
5.3.4 Flared joints
Flared joints should be used where a screw thread connection is required.
»Before flaring 1/2H (half hard) piping, anneal the end of the pipe to be flared.
»Remember to place the flare nut on the piping before flaring.
»Ensure the flared opening is not cracked, deformed or scratched, otherwise it will
not form a good seal and refrigerant leakage may occur.
»The diameter of the flared opening should be within the ranges specified in the
table below. Refer to Figure 5.2.
Pipe (mm) Flared opening diameter
(A) (mm)
Figure 5.2 Flared opening
Ø 6.35 8.7 - 9.1
Ø 9.53 12.8 - 13.2
Ø 12.7 16.2 - 16.6
Ø 15.9 19.3 - 19.7
Ø 19.1 23.6 - 24.0
»When connecting a flared joint, apply some compressor oil to the inner and outer

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surfaces of the flared opening to facilitate the connection and rotation of the flare
nut, ensure firm connection between the sealing surface and the bearing surface,
and avoid the pipe becoming deformed.
5.3.5 Bending piping
Piping bending methods
»Hand bending is suitable for thin copper piping (Ø6. 35mm - Ø12. 7mm).
»Mechanical bending (using a bending spring, manual bending machine or powered
bending machine) is suitable for a wide range of diameters (Ø6. 35mm - Ø54.0mm).
CAUTION!
»When using a spring bender, ensure that the bender is clean before inserting it in
the piping.
»After bending a copper pipe, ensure that there are no wrinkles or deformation on
either side of the pipe.
»Ensure that bend angles do not exceed 90°, otherwise wrinkles may appear on the
inner side of the pipe, and the pipe may buckle or crack. Refer to Figure 5.3.
»Do not use a pipe that has buckled during the bending process; ensure that the
cross section at the bend is greater than 2/3 of the original area.
Figure 5.3 Pipe bending in excess of 90°
5.4 Refrigerant Piping Supports
When the air conditioner is running, the refrigerant piping will deform (shrink, expand,
droop). To avoid damage to piping, hangers or supports should be spaced as per the
criteria in the table below. In general, the gas and liquid pipes should be suspended in
parallel and the interval between support points should be selected according to the
diameter of the gas pipe.
Pipe (mm) Interval between support points (m)
Horizontal Piping Vertical Piping
< Ø20 1 1.5
Ø20 – Ø40 1.5 2
> Ø40 2 2.5
Suitable insulation should be provided between the piping and the supports. If wooden
dowels or blocks are to be used, use wood that has undergone preservative treatment.
Changes in refrigerant flow direction and refrigerant temperature result in movement,

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expansion and shrinkage of the refrigerant piping. Piping should therefore not be
fixed too tightly, otherwise stress concentrations may occur in the piping, with the
potential for rupturing.
5.5 Brazing
Care must be taken to prevent oxide forming on the inside of copper piping during
brazing. The presence of oxide in a refrigerant system adversely affects the operation
of valves and compressors, potentially leading to low efficiency or even compressor
failure. To prevent oxidation, during brazing nitrogen should be flowed through the
refrigerant piping.
CAUTION!
»Never flow oxygen through piping as doing so aids oxidation and could easily lead
to explosion and as such is extremely dangerous.
»Take appropriate safety precautions such as having a fire extinguisher to hand
whilst brazing.
Flowing nitrogen during brazing
»Use a pressure reducing valve to flow nitrogen through copper piping at 0.02-
0.03MPa during brazing.
»Start the flow before brazing starts and ensure that the nitrogen continuously
passes through the section being brazed until the brazing is complete and the
copper has cooled down completely.
Figure 5.4 Flowing nitrogen through piping during brazing Legend
1Copper piping
2Section being brazed
3Nitrogen connection
4 Hand valve
5 Pressure-reducing valve
6 Nitrogen
»When joining a shorter section of piping to a longer section, flow nitrogen from the
shorter side to allow better displacement of air with nitrogen.
»If the distance from the point where nitrogen enters the piping to the joint to be
brazed is long, ensure that the nitrogen is flowed for sufficient time to discharge all
the air from the section to be brazed before commencing brazing.

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Figure 5.5 Flowing nitrogen from shorter side during brazing
Piping orientation during brazing
Brazing should be conducted downwards or horizontally to avoid filler leakage.
Figure 5.6 Piping orientation during brazing
Piping overlap during brazing
The table below specifies the minimum permissible piping overlap and the range of
permissible gap sizes for brazed joints on piping of different diameters. Refer also to
Figure 5.7.
D (mm) Minimum permissible B (mm) Permissible A – D (mm)
5 < D < 8 6 0.05 - 0.21
8 < D < 12 7
12 < D < 16 8 0.05 - 0.27
16 < D < 25 10
25 < D < 35 12 0.05 - 0.35
35 < D < 45 14
Figure 5.7 Piping overlap and gap for brazed joints
Legend
A Inner diameter of larger pipe
D Outer diameter of smaller pipe
B Inlaid depth (overlap)

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Filler
»Use a copper/phosphorus brazing alloy (BCuP) filler that does not require flux.
»Do not use flux. Flux can cause corrosion of piping and can affect the performance
of compressor oil.
»Do not use anti-oxidants when brazing. Residue can clog piping and damage
components.
5.6 Pipe Flushing
5.6.1 Purpose
To remove dust, other particles and moisture, which could cause compressor
malfunction if not flushed out before the system is run, the refrigerant piping should
be flushed using nitrogen. As described in 5.1.1 “Installation procedure”, pipe flushing
should be performed once the piping connections have been completed with the
exception of the final connections to the indoor units. That is, flushing should be
performed once the outdoor units have been connected but before the indoor units
are connected.
5.6.2 Procedure
CAUTION!
Only use nitrogen for flushing. Using carbon dioxide risks leaving condensation in the
piping. Oxygen, air, refrigerant, flammable gases and toxic gases must not be used for
flushing. Use of such gases may result in fire or explosion.
Procedure
The liquid and gas sides can be flushed simultaneously; alternatively, one side can be
flushed first and then Steps 1 to 8 repeated, for the other side. The flushing procedure
is as follows:
1. Cover the inlets and outlets of the indoor units to prevent dirt getting blown in
during pipe flushing. (Pipe flushing should be carried out before connecting the
indoor units to the piping system.)
2. Attach a pressure reducing valve to a nitrogen cylinder.
3. Connect the pressure reducing valve outlet to the inlet on the liquid (or gas) side
of the outdoor unit.
4. Use blind plugs to block all liquid (gas) side openings, except for the opening at the
indoor unit which is furthest from the outdoor unit (“Indoor unit A” in Figure 5.8.)
5. Start to open the nitrogen cylinder valve and gradually increase the pressure to
0.5MPa.
6. Allow time for nitrogen to flow as far as the opening at indoor unit A.
7. Flush the first opening:
a. Using suitable material, such as a bag or cloth, press firmly against the
opening at indoor unit A.
b. When the pressure becomes too high to block with your hand, suddenly
remove your hand allowing gas to rush out.
c. Repeatedly flush in this manner until no further dirt or moisture is emitted
from the piping. Use a clean cloth to check for dirt or moisture being emitted.
Seal the opening once it has been flushed.
8. Flush the other openings in the same manner, working in sequence from indoor
unit A towards the outdoor unit.

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9. Once flushing is complete, seal all openings to prevent dust and moisture from
entering.
Figure 5.8 Pipe flushing using nitrogen
Outdoor
nitrogen gas cylinder
Indoor
unit
unit A
gas pipe
liquid pipe
5.7 Gas tightness test
5.7.1 Purpose
To prevent faults caused by refrigerant leakage, a gas tightness test should be
performed before system commissioning.
5.7.2 Procedure
CAUTION!
Only dry nitrogen should be used for gas tightness testing. Oxygen, air, flammable
gases and toxic gases must not be used for gas tightness testing. Use of such gases
may result in fire or explosion.
Procedure
The gas tightness test procedure is as follows:
Step 1
»Once the piping system is complete and the indoor and outdoor units have been
connected, vacuum the piping to -0.1MPa.
Step 2
»Charge the indoor piping with nitrogen at 0.3MPa through the needle valves on the
liquid and gas stop valves and leave for at least 3 minutes (do not open the liquid or
gas stop valves). Observe the pressure gauge to check for large leakages. If there is
a large leakage, the pressure gauge will drop quickly.
»If there are no large leakages, charge the piping with nitrogen at 1.5MPa and leave
for at least 3 minutes. Observe the pressure gauge to check for small leakages. If
there is a small leakage, the pressure gauge will drop distinctly.
»If there are no small leakages, charge the piping with nitrogen at 4.2MPa and leave
for at least 24 hours to check for micro leakages. Micro leakages are difficult to
detect. To check for micro leakages, allow for any change in ambient temperature
over the test period by adjusting the reference pressure by 0.01MPa per 1°C of
temperature difference. Adjusted reference pressure = Pressure at pressurization +

EN
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(temperature at observation – temperature at pressurization) x 0.01MPa. Compare
the observed pressure with the adjusted reference pressure. If they are the same,
the piping has passed the gastightness test. If the observed pressure is lower than
the adjusted reference pressure, the piping has a micro leakage.
»If the leakage is detected, refer to 5.7.3 “Leak detection”. Once the leak has been
found and fixed, the gas tightness test should be repeated.
Step 3
»If not continuing straight to vacuum drying (see 5.8 “Vacuum Drying”) once the gas
tightness test is complete, reduce the system pressure to 0.5-0.8MPa and leave the
system pressurized until ready to carry out the vacuum drying procedure.
Figure 5.9 Gas tightness test
LIQUID PIPE
GAS PIPE
GAS SIDE
STOP VALVE
MISTRAL MDX
INDOOR UNIT
MISTRAL MDX
OUTDOOR UNIT
LIQUID SIDE
STOP VALVE
NITROGEN
5.7.3 Leak detection
The general methods for identifying the source of a leak are as follows:
1. Audio detection: relatively large leaks are audible.
2. Touch detection: place your hand at joints to feel for escaping gas.
3. Soapy water detection: small leaks can be detected by the formation of bubbles
when soapy water is applied to ajoint.
4. Refrigerant leak detection: for leaks that are difficult to detect, refrigerant leak
detection may be used as follows:
a. Pressurize the piping with nitrogen at 0.3MPa.
b. Add refrigerant into the piping until the pressure reaches 0.5MPa.
c. Use a halogen refrigerant detector to find the leak.
d. If the leak source cannot be found, continuing charging with refrigerant to a
pressure of 4MPa and then search again.
5.8 Vacuum Drying
5.8.1 Purpose
Vacuum drying should be performed in order to remove moisture and non-condensable
gases from the system. Removing moisture prevents ice formation and oxidization
of copper piping or other internal components. The presence of ice particles in the

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system would cause abnormal operation, whilst particles of oxidized copper can cause
compressor damage. The presence of non-condensable gases in the system would
lead to pressure fluctuations and poor heat exchange performance.
Vacuum drying also provides additional leak detection (in addition to the gas tightness
test).
5.8.2 Procedure
During vacuum drying, a vacuum pump is used to lower the pressure in the piping to
the extent that any moisture present evaporates. At 5mmHg (755mmHg below typical
atmospheric pressure) the boiling point of water is 0°C. Therefore a vacuum pump
capable of maintaining a pressure of -756mmHg or lower should be used. Using a
vacuum pump with a discharge in excess of 4L/s and a precision level of 0.02mmHg
is recommended.
CAUTION!
»Before performing vacuum drying, make sure that all the outdoor unit stop valves
are firmly closed.
»Once the vacuum drying is complete and the vacuum pump is stopped, the low
pressure in the piping could suck vacuum pump lubricant into the air conditioning
system. The same could happen if the vacuum pump stops unexpectedly during
the vacuum drying procedure. Mixing of pump lubricant with compressor oil could
cause compressor malfunction and a one-way valve should therefore be used to
prevent vacuum pump lubricant seeping into the piping system.
Procedure
The vacuum drying procedure is as follows:
Step 1
»Connect the blue (low pressure side) hose of a pressure gauge to the outdoor unit
gas pipe stop valve, the red (high pressure side) hose to the outdoor unit liquid pipe
stop valve and the yellow hose to the vacuum pump.
Step 2
»Start the vacuum pump and then open the pressure gauge valves to start vacuum
the system.
»After 30 minutes, close the pressure gauge valves.
»After a further 5 to 10 minutes check the pressure gauge. If the gauge has returned
to zero, check for leakages in the refrigerant piping.
Step 3
»Re-open the pressure gauge valves and continue vacuum drying for at least 2 hours
and until a pressure difference of 756mmHg or more has been achieved. Once
the pressure difference of at least 756mmHg has been achieved, continue vacuum
drying for 2 hours.
Step 4
»Close the pressure gauge valves and then stop the vacuum pump.
»After 1 hour, check the pressure gauge. If the pressure in the piping has not increased,
the procedure is finished. If the pressure has increased, check for leakages.