Johnson Controls YORK EMHC 18 Instrucciones De Instalación página 14

by johnson controls
Installation of interconnecting
pipes
The length of the interconnecting tubing of
the units should be as short as possible.
The maximum admissible distances with
regard to the circuit and standard tubing
diameters are indicated on each apparatus
of the corresponding indoor units.
Pipes to be used
Special care should be taken that the tubing
that interconnects the two units is kept
clean and dry, even prior to installation. It is
advisable to take into account the following
recommendations:
- Use copper refrigerant quality tubing
only.
- Do not work outdoors when raining.
- The ends of the tubing should remain
closed during installation.
- Do not leave dryer filters or the compressor
out in the open air.
- For welding use low melting point rods
with a 5% silver content, minimum.
- When welding and as long as the tubing is
hot, maintain a flow of dry nitrogen so as to
avoid internal rusting and scaling that could
cause contamination and obstructions.
- Do not use strippers on copper-copper
joints.
- Connection between units should be
carried out by means of the flaring
method.
Insulation of refrigerant pipes
Due to the fact that the capillary piping is
installed in the outdoor unit, both the larger
as well as the smaller diameter pipes are
in the relative low pressure side of the
system.
Consequently, to avoid condensed water
dripping on the floor, both pipes should
be insulated adequately. The thickness of
same should be at least 8 mm. (see Fig.
17).
Emptying and dehydrating
(Figs. 18 and 19)
Air does not act as a refrigerant since it
cannot be liquefied by the compressor.
Any air and humidity remaining in the
cooling system has undesirable effects, as
indicated below. Consequently, they should
be eliminated completely.
- High pressure increases.
- Consumed power supply increases.
- Equipment performance decreases.
- Water contained in the air could freeze
and block the capillaries.
- Water can cause corrosion of certain
parts of the circuit, and deterioration of
the compressor.
14
Process
- Fit an adapter to the pump to avoid
contamination of the POE oil.
- Connect the vacuum pump and service
pressure gauges to the system.
- Carry out a vacuum of up to at least 50
microns.
- Make sure the system does not loose
vacuum.
- If it does, detect leaks and repair.
Cooling Interconnections
R-410A refrigerant
- R-410A refrigerant is a 50% binary mixture
of HFC-32 and HFC-125. Its reaction as a
refrigerant gas is nearly azeotropic (creep
below 0.17°K). Does not contain chlorine
and, thus, it does not harm the ozone layer.
Nevertheless, should a circuit be drained,
the gas should always be recovered and in
no case released in the atmosphere.
- In comparison to R-22, R-410A operates
at higher pressures. At 60% higher on the
high side and at 75% more on the low side.
See following table.
Temperature °C R-410A pressure bar g
-1
7
43
54
- R-410A refrigerant should be charged
always in liquid form. Should the tank not
have a dipping pipe, it should be turned
upside down.
- The R-410A refrigerant tanks stand out
because they are pink.
- Due to the fact that it does not contain
chlorine, R-410A refrigerant can be used
only in combination with POE (Polyol
Ester) type synthetic oil.
- R-410A refrigerant is not flammable at
atmospheric pressure. Nevertheless, as it
contains 50% HFC-32, it should never be
pressurised with air or any gas other than
nitrogen (the same as R-22).
POE oil
- POE oil is highly hygroscopic. Its water
absorbing capacity is 15 times greater
than mineral oil.
- POE oil containers should be metallic
and should be kept open the least time
possible. They should be hermetically
sealed after use.
- Never open a circuit or compressor charged
with POE oil while under vacuum. Should
either one be under atmospheric pressure,
it should not remain open for more than
GB
15 minutes. Should this not be possible, a
flow of dry nitrogen should be established.
- POE oil cannot be mixed with mineral oil.
Amounts of over 5% of mineral oil mixed
with POE will cause transitory obstructions
within the expansion systems..
- It is recommendable to use filter-dryers on
systems using POE oil.
- Should the POE oil become contaminated
with water, a vacuum pump is no longer
sufficient. Excessive presence of humidity
causes sludge and acids that damage the
compressor. Therefore, any contaminated
oil should be changed or recovered by
means of filters.
- Due to its high hygroscopic nature, POE
oil can cause burns on the skin. The use of
gloves during handling is recommended.
- The POE oils that are adequate for R-410A
systems are as follows:
MOBIL EAL ARCTIC 22 CC (ICI)
EMKARATE RL32CF (ICI)
Specific tools
For installing equipment charged with
R-410A refrigerant and POE oil, the following
tools are required:
- Pressure gauges. Specific for R-410A.
High pressure (red) with a range of -1 to
53 bar. Low pressure (blue) with a range
6,8
of -1 to 38 bar. With ½" threaded UNF-20
connections.
8,9
- Hoses. Of HNBR rubber and with nylon
internal lining. Operating pressure 5.1
25
Mpa, bursting pressure 27.4 Mpa. ½"
UNF-20 thread.
32,6
- Vacuum pump. High vacuum (two stages)
and with adapter to avoid part of the mineral
oil in the pump from flowing towards the
circuit charged with POE oil. With adapter
for ½" UNF-20 thread.
- Electronic scale. Needed because it is
impossible to charge R-410A by using a
charge cylinder due to the bubbles caused
by the high pressure and speed of gas
evaporation.
- Refrigerant tank. Adequate for a pressure
of 47 bar and for containing R-410A only
(painted pink). With adapter for ½" UNF-
20 thread.
- Leak detector. Specific for HFC. Sensitivity
of approximately 23 gr. year.
- Recovery equipment. Specific unit for
recovery of R-410A.
Minimum thickness of tubing
Due to the greater operating pressures
of R-410A refrigerant, the interconnection
of the split units requires seamless DHP
copper tubing with thicker walls.