Installation Guideline - Carrier 38AUM Series Installation, Operation & Maintenance Manual

INSTALLATION GUIDELINE

Replacement/Retrofit – R-22 to Puron®
Replacement/retrofit installations require change-out of outdoor unit, metering device, and filter driers. Change-out of
indoor coil (evaporator) and interconnecting tubing is recommended.
Existing evaporator coil – If the existing evaporator coil may be re-used, check with the coil manufacturer to verify
the coil construction is suitable for operation with the higher pressures of Puron® (R-410A). Also determine if the
existing TXV valve is compatible with R-410A, replace if necessary. The minimum factory test pressure rating must be
2413 kPa (350 psig). Existing coil will need to be purged with Nitrogen to remove as much mineral oil as possible to
eliminate cross contamination of oils.
Acid test – If the existing system is being replaced because of a compressor electrical failure, assume acid is in
system. If system is being replaced for any other reason, use an approved acid test kit to determine acid level. If even
low levels of acid are detected, install a 100 percent activated alumina suction-line filter drier in addition to the
replacement liquid-line filter drier. Remove the suction line filter drier as soon as possible, with a maximum of 72 hr of
operation. Recommendation: Install a ball valve in the liquid line at the filter drier location when installing a suction
filter in the suction line.
Existing refrigeration piping – Reuse of existing refrigerant piping involves three issues: quality (strength) of existing
tubing, cleanliness and tube size. Inspect all tube segments and joints for signs of damage, corrosion or poor brazing.
Flush the interconnecting piping system with dry Nitrogen to eliminate as much trace of mineral oil as possible.
Same tube sizes are capable of handling higher flow rates (expressed as tons of cooling capacity) with Puron
refrigerant compared to R-22 at constant pressure drops. For example, a 1/2-inch OD liquid line is rated at 33% higher
tons with Puron® than with R-22 (at 5°pressure drop). A 1 1/8-inch OD suction line is rated at 53% higher tons with
Puron® than with R-22 (at 2° pressure drop). Refrigeration lines selected for R-22 use are typically oversized for
Puron® applications. Carefully check the existing suction line size against the table for maximum size (see Table
Piping Recommendation); replace vertical riser segments if necessary. Check existing liquid line size against sizing
data (see Table Piping Recommendation); replace with smaller lines when feasible.
Installation
1. Remove the existing evaporator coil or fan coil and install the replacement coil when appropriate.
2. Drain oil from low points and traps in suction line tubing (and hot gas bypass tubing if appropriate) and evaporator if
they were not replaced. Removing oil from evaporator coil may require purging of the tubing with dry nitrogen.
3. Unless indoor unit is equipped with a Puron® approved metering device, change the metering device to a thermal
expansion valve (TXV) designed for Puron® (R-410A).
4. Remove the existing outdoor unit. Install the new outdoor unit according to these installation instructions.
5. Install a new field-supplied liquid-line filter drier at the indoor coil just upstream of the TXV or fix orifice metering
device.
6. If a suction line filter drier is also to be installed, install suction line drier downstream of suction line service valve at
condensing unit.
Failure to follow this caution may result in equipment damage.
Never install suction-line filter drier in the liquid-line of a Puron® system.
7. If required, install a 100% activated alumina suction line filter drier at the outdoor unit.
8. Evacuate and charge the system according to the instructions in this installation manual.
9. Operate the system for 10 hr. Monitor the pressure drop across the suction line filter drier. If pressure drop exceeds
21kPa (3 psig), replace suction-line and liquid-line filter driers. Be sure to purge system with dry nitrogen and evacuate
when replacing filter driers. Continue to monitor the pressure drop across suction-line filter drier. Repeat filter changes
is necessary. Never leave suction-line filter drier in system longer than 72 hr (actual time).
CAUTION
UNIT DAMAGE HAZARD
Page 7