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171
Cleaning
Inspect unit at the beginning of each heating and cooling season
and during each season as operating conditions may require.
MICROCHANNEL HEAT EXCHANGER (MCHX) CON
-
DENSER COIL MAINTENANCE AND CLEANING
RECOMMENDATIONS
Routine cleaning of coil surfaces is essential to maintain proper
operation of the unit. Elimination of contamination and remov
-
al of harmful residues will greatly increase the life of the coil
and extend the life of the unit. The following steps should be
taken to clean MCHX condenser coils:
1. Remove any foreign objects or debris attached to the core
face or trapped within the mounting frame and brackets.
2. Put on personal protective equipment, including safety
glasses and/or face shield, waterproof clothing, and
gloves. It is recommended to use full-coverage clothing.
3. Start high-pressure water sprayer and purge any soap or
industrial cleaners from sprayer before cleaning condenser
coils. Only clean, potable water is authorized for cleaning
condenser coils.
4. Clean condenser face by spraying the core steadily and uni
-
formly from top to bottom while directing the spray straight
toward the core. Do not exceed 30 degree angle. The nozzle
must be at least 12 in. from the core face. Reduce pressure
and use caution to prevent damage to air centers.
CONDENSATE DRAIN
Check and clean each year at start of cooling season. In winter,
keep drains and traps dry.
FILTERS
Clean or replace at start of each heating and cooling season or
more often if operating conditions require. Refer to Installation
Instructions for type and size.
1. Remove economizer outdoor-air filters from the hoods by
removing the filter retainers.
2. Clean filters with steam or hot water and mild detergent.
3. Reinstall filters in hoods after cleaning. Never replace
cleanable filters with throwaway filters.
OUTDOOR-AIR INLET SCREENS
Clean screens with steam or hot water and a mild detergent. Do
not use disposable filters in place of screens.
Lubrication
FAN SHAFT BEARINGS
Lubricate fan shaft bearings at least once a year with suitable
bearing grease. Optional extended grease lines may be provid
-
ed on pulley side of blower. See table for typical lubricants.
* Preferred lubricant because it contains rust and oxidation inhibitors.
FAN MOTOR BEARINGS
The condenser-fan motors have sealed bearings so no field lu
-
brication is required.
DOOR HINGES
All door hinges should be lubricated at least once a year.
Electronic Expansion Valve (EXV)
Each circuit has 2 EXVs on which superheat may be adjusted if
necessary by using the
Comfort
Link controller. Adjustment is
not normally required or recommended.
The TXV is set to maintain 10 to 13°F superheat leaving the
evaporator coil. It controls the flow of refrigerant to the evapo
-
rator coils.
Refrigeration Circuits
LEAK TESTING
Units are shipped with a full operating charge of R-410A (see
unit nameplate). If there is no pressure in the system, introduce
enough nitrogen to search for the leak. Repair the leak using
good refrigeration practices. After leaks are repaired, system
must be evacuated and dehydrated using methods described in
GTAC II, Module 4, System Dehydration.
REFRIGERANT CHARGE
Amount of refrigerant charge is listed on unit nameplate. Refer
to Carrier GTAC II; Module 5; Charging, Recovery, Recycling,
and Reclamation section for charging methods and procedures.
Unit panels must be in place when unit is operating during
charging procedure.
NOTE: Do not use recycled refrigerant as it may contain
contaminants.
NO CHARGE
Use standard evacuating techniques. After evacuating system,
weigh in the specified amount of refrigerant from the unit
nameplate.
LOW CHARGE COOLING
Due to the compact, all-aluminum design, microchannel heat
exchangers will reduce refrigerant charge and overall operating
weight. As a result, charging procedures for MCHX units re
-
quire more accurate measurement techniques. Charge should
be added in small increments. Using cooling charging charts
provided (Fig. 56-77), add or remove refrigerant until condi
-
tions of the chart are met. As conditions get close to the point
on the chart, add or remove charge in
1
/
4
-lb increments until
complete. Ensure that all fans are on and all compressors are
running when using charging charts.
To Use the Cooling Charging Chart
Use the outdoor air temperature, saturated suction temperature
(SST), and saturated condensing temperature (available on the
Comfort
Link display), and find the intersection point on the
cooling charging chart. If intersection point is above the line,
carefully recover some of the refrigerant. If intersection point
is below the line, carefully add refrigerant.
NOTE: Indoor-air cfm must be within normal operating range
of unit.
CAUTION
Do not apply any chemical cleaners to MCHX condenser coils.
These cleaners can accelerate corrosion and damage the coils.
CAUTION
Excessive water pressure will fracture the braze between air
centers and refrigerant tubes.
MANUFACTURER
LUBRICANT
Texaco
Regal AFB-2*
Mobil
Mobilplex EP No. 1
Sunoco
Prestige 42
Texaco
Multifak 2
Содержание WeatherExpert 48N2
Страница 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Страница 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Страница 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Страница 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Страница 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Страница 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Страница 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Страница 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Страница 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Страница 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Страница 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Страница 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Страница 168: ...168 Fig 47 Sensor and Ignition Position Fig 48 Combustion Blower Details SENSOR DETAILS IGNITION DETAILS ...
Страница 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...