Table 9: Replacing refrigerant piping
Installation condition Approach
You are replacing an outdoor unit that uses
R-22, R-410A, or other refrigerant with an
outdoor unit that uses R-454B refrigerant
Replace the refrigerant piping to reduce
cross-contamination of oils and refrigerants.
See .
If replacing the refrigerant piping is not
practical, take the following precautions:
1. Inspect the refrigeration piping for kinks,
sharp bends or other restrictions, and for
corrosion.
2. Determine if there are any low spots
which might be serving as oil traps.
3. Flush the refrigeration piping with
a commercially available flush kit to
remove as much of the existing oil and
contaminants as possible.
4. Install a suction line filter-drier to trap
any remaining contaminants, and remove
after 50 h of operation.
You are replacing the outdoor unit because
of a compressor burnout
Replace the refrigerant piping or, at a
minimum, thoroughly flush the refrigerant
piping with a commercially available flush kit.
6. If the outdoor unit is being replaced due to a compressor burnout, then the installation of a
100% activated alumina suction-line filter-drier in the suction-line is required, in addition to
the field-installed biflow liquid-line drier. Take the following steps:
- Operate the system for 10 h. Monitor the suction drier pressure drop.
- If the pressure drop exceeds 3 psig, replace both the suction-line and liquid-line driers.
- After a total of 10 h runtime where the suction-line pressure drop has not exceeded 3
psig, replace the liquid-line drier, and remove the suction-line drier.
Installation Manual: R-454B Outdoor Split-System Air Conditioner22
Johnson Controls Ducted Systems
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