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18 - SAFETY CONSIDERATIONS
Before connecting the refrigerant lines carefully follow the
steps below:
- Remove the freon holding charge from the refrigerant
circuits.
- Select the diameter of the copper tubing according the
units installed and according to the distance between the
indoor and outdoor units.
- Use silver alloy rod for soldering purposes and ensure that
this work is done in a nitrogen atmosphere.
- To avoid oxidation insulate the refrigerant lines adequately.
- Pull a vacuum in the refrigerant circuit until a pressure of
6.9 Pa is maintained for at least 2 hours.
- Charge the refrigerant circuit with the necessary amount
of R-410A refrigerant (in accordance with table 1 and the
length of the refrigerant lines).
- Check there are no refrigerant leaks.
The following conditions should be observed:
- The maximum speed permitted in any line is 15 m/s.
- Suction line must be insulated and have a 2% slope towards
the compressor and the horizontal pipe run.
- In long pipe runs it is be necessary to adjust the oil charge &
freon amount.
- If the liquid line flow is downward, it is necessary to install
pressure equalizer for heights above 10 m.
- The liquid should be subcooled by at least 1 K at the
expansion inlet. In this case, if the liquid line flow is upward
and the pipe is longer than 15 m, it must be subcooled by
1 K for each 3.5 m in excess of 15 m.
- Subcooling can be contained in the liquid and suction lines
(maximum 15 m) of the units.
- For each meter of refrigerant pipe installed, refrigerant has
to be added in accordance with below table.
Necessary checks/precautions before start-up:
- Ensure that all electrical connections are properly
tightened.
- Ensure that the unit is level and well-supported.
- Check the condition of the ductwork in case damage has
occurred during installation.
- The air filter should be clean and in place.
- All the panels should be fitted and firmly secured with the
corresponding screws.
- Make sure that there is sufficient space for servicing and
maintenance purposes.
- Check the drain connections.
- Ensure that there are no refrigerant leaks.
- Confirm that the electrical power source agrees with the
unit nameplate rating.
WARNING: The compressors are mounted on vibration
isolators. Do not loosen or remove the support mounting bolts.
- Check for proper fan rotation.
Refrigerant guidelines for R-410A:
Refrigerant R-410A consists of a non-azeotropic blend of 50%
of R-32, 50% of R-125, and is characterised by the fact that at
the time of the change in state the
temperature of the liquid/vapour mixture is not constant.
All checks must be pressure tests, and the appropriate pres-
sure/temperature ratio table must be used for the interpreta-
tion of the values.
Leak detection is especially important for units charged with
refigerant R-410A. Depending on whether the leak occurs in
the liquid or the vapour phase, the proportion of the different
components in the mixture remaining in the unit is not the
same.
The following basic guidelines must be observed:
• Leaks must be repaired immediately by qualified personnel.
• Refrigerant must never be discharged to the atmosphere.
• Use a refrigerant reclaim unit.
• Any loss of oil from the system during maintenance must
be stopped immediately and the collected oil must by
removed in accordance with applicable regulations
38RM-N units are supplied with a freon holding charge. This
must be removed before soldering the connecting refrigerant
lines to the unit. Once the soldering has been completed,
the complete refrigerant circuit must be evacuated then the
correct quantity of R-410A refrigerant for each system must
be charged.
WARNING: If any brazing is to be done the refrigerant circuit
must be filled with nitrogen. Combustion of refrigerant
produces toxic phosgene gas.
VERY IMPORTANT:
- Never use the compressor as a vacuum pump.
- Liquid refrigerant must never be introduced into the suction
line.
- Do not overcharge with refrigerant.
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