AAON RN Series 6 - 140 tons Outdoor Heat Pump Yearly Maintenance

The AAON RN Series 6 - 140 tons Outdoor Heat Pump Yearly Maintenance emphasizes safety on all steps when maintenance is being conducted on the machine. Finishing this lenghty procedure ensures that the quality of performance does not drop.

MaintainX

04/26/2021

AAON RN Series 6 - 140 tons Outdoor Heat Pump Yearly Maintenance

At least once each year, a trained, qualified service technician should check out the unit. Fans, evaporator coils, and filters should be inspected at least monthly.

Gas Heating

WARNING! Once a year, before the unit is in operation for the heating season, a qualified service technician should inspect all flue product carrying areas of the furnace and main burners for continued safe operation.

DANGER! LEAK CHECK GAS PIPE The gas pipe in the unit should be checked for leaks before startup. Leak checking is the responsibility of the installing contractor. All connections should be checked for leaks annually after installation. Failure to leak che

Make sure all gas supply lines have been purged of air before turning on the electrical power switch.

Turn the gas valve to the on position (see startup instructions).

Turn the main electrical power on and set the controls to the heating mode of operation.

The combustion ventilation motor should operate.

The control will automatically supply energy to the igniter and the gas valve after the heating call is made.

The flame sensing probe detects the presence of the flame. Should no flame be detected in 10 seconds, the ignition system will recycle.

If no flame is detected after 3 tries, ignition system will lockout.

Remove the call for heating. The main gas valves should be extinguished.

The supply fans are controlled by the ignition system. In the fan “Auto” mode the fan comes on 45 seconds after the flame is proved and goes off 120 seconds after the heating call is removed.

Furnace combustion ventilation air and flue openings should be checked annually for debris and obstructions. If vent extensions are used they must meet category III requirements.

This appliance contains a wire screen at the vent outlet. Each heating season, prior to placing the appliance in heat mode maintenance check that no debris or foreign matter has accumulated in the vent outlet. A good practice is to check for debris each t

In the event the vent outlet becomes blocked do not attempt to start the appliance in heat mode until the entire vent opening is cleared.

In the event the unit shut down because the vent was blocked a qualified technician or service agency should monitor the unit prior to re-starting.

The gas burner and heat exchanger should never require cleaning. If cleaning is necessary, this indicates faulty operation of the unit.

Cleaning should only be done by a qualified service agency and only after consultation with an AAON service representative.

If induced draft blower/motor assembly has to be replaced, care must be taken to provide an airtight seal between the blower housing and the burner box.

Gas Heat Exchanger Removal

WARNING! Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

DANGER! LEAK CHECK GAS PIPE The gas pipe in the unit should be checked for leaks before startup. Leak checking is the responsibility of the installing contractor. All connections should be checked for leaks annually after installation. Failure to leak ch

Removal

Disconnect all wiring on the heat exchanger.

Disconnect flex gas lines and pull out of the way.

Remove screws around the perimeter of the heat exchanger face plate that connect it to the unit. Only the outermost screws should be removed.

Pull the heat exchanger straight back and out of the unit. It may be necessary to remove some of the control door jambs.

Reinstallation

Ensure that the neoprene isolator is installed around the perimeter of the heat exchanger.

Insert heat exchanger into opening so that the back of the main plate is against the unit bulkhead.

Figure 51 - Gas Heat Exchanger

Attach the heat exchanger to the bulkhead using the holes around the perimeter.

Connect flex gas lines to the piping on the heat exchanger. If flexible gas piping in the unit must be replaced connectors cannot be reused, only new connectors must be used.

Connect wiring per the wiring diagram on the controls compartment door.

Purge gas lines to the gas valves at the unit.

DX Cooling

Set unit controls to cooling mode of operation with supply fans on.

Check the fan for correct operating direction, amperage and voltage.

Check compressor operation, rotation, amperage and voltage to the unit nameplate (check the amperage on the load side of the compressor contactor).

Condenser Fans (6-25 and 30 ton)

Condenser fans and motors can be removed and reinstalled as individual assemblies.

WARNING! Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

WARNING! Improper installation, adjustment, alteration, service, or maintenance can cause property damage, personal injury, or loss of life. Startup and service must be performed by a Factory Trained Service Technician.

Removal

Take off the fan grill by removing the screws that attach it to the orifice.

The condenser fan motor wires can then be accessed and disconnected.

Remove the screws that attach the orifice to the condenser assembly. The screws are located on the top of the orifice around the perimeter, and in some cases, through the side of the condenser assembly into the orifice.

With the wires disconnected and the screws removed, the fan, motor and orifice assembly can be lifted off the unit

Figure 52 - Removal of a Condenser Fan Assembly

Reinstallation

Set the condenser fan, motor and orifice assembly back into the condenser assembly with the motor wires on the side closest to the control panel.

Attach the orifice to the condenser assembly using all of the points where screws were removed.

Reconnect the fan motor wires.

Attach the fan grill at all of the points where screws were removed.

Condensate Drain Pans

Drain pans will have moisture present and require periodic cleaning to prevent microbial growth.

Cleaning of the drain pans will also prevent any possible plugging of the drain lines and overflow of the pan itself.

Cleaning of the drain pans and inside of the unit should be done only by qualified service technician

Evaporator Coil (6-25 and 30 ton)

WARNING! Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

Removal

Evacuate refrigerant from the systems.

Remove the expansion valve bulbs from the suction lines.

Disconnect the suction and liquid line copper connections to the evaporator coil.

Figure 53 - Evaporator Coil Access

Remove the screws attaching the filter rack to the evaporator coil blank-off panels at the door opening and along the top of the coil.

Remove the screws attaching the filter rack to the back wall. Angle filter rack away from coil so it fits through the door opening. It may be necessary to remove economizer damper assembly.

Remove screws attaching access side, back, and top blank-off panels to the evaporator coil and the unit.

Angle the coil so that it fits through the door opening. Remove the evaporator coil.

Reinstallation

Install the coil in the unit drain pan. There should be about a 1/4” gap between the upstream side of the coil and the back of the drain pan

Secure the coil to the back wall of the unit with the blank-off panel. Attach the top and access side blank-off panels to the coil.

Attach the filter rack to the back, top, and access side coil blank-off panels upstream of the coil.

Reinstall economizer damper assembly if necessary.

Connect the suction and liquid copper connections to the evaporator coil.

Reinstall the expansion valve bulbs on the suction lines.

Evacuate the refrigerant systems. Weigh in the nameplate refrigerant charge.

See Adjusting Refrigerant Charge section to check for proper sub-cooling and superheat of the refrigerant systems.

Brazed Plate Heat Exchanger Cleaning

Because of a normally high degree of turbulence in brazed plate heat exchangers, for many applications the heat exchanger channels are self cleaning.

For applications that are not self cleaning (i.e. hard water at high temperatures, etc.) or applications where additional cleaning is desired, it is possible to clean the brazed plate heat exchanger by circulating a cleaning liquid.

Use a tank with weak acid, 5% phosphoric acid (H3PO4) or, if the exchanger is frequently cleaned, 5% oxalic acid (H2C2O4).

Pump the cleaning liquid through the exchanger. For optimum cleaning, the cleaning solution flow rate should be a minimum of 1.5 times the normal flow rate, preferably in a back-flush mode.

After cleaning, the heat exchanger must be rinsed with clean water. A solution of 1-2% sodium hydroxide (NaOH) or sodium bicarbonate (NaHCO) before the last rinse ensures that all acid is neutralized.

E-Coated Coil Cleaning

Documented quarterly cleaning of e-coated coils is required to maintain coating warranty coverage.E-Coated Coil Maintenance Record document is available on the AAON website

WARNING! Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

Surface loaded fibers or dirt should be removed prior to water rinse to prevent restriction of airflow. If unable to back wash the side of the coil opposite of the coils entering air side, then surface loaded fibers or dirt should be removed with a vacuum

If a vacuum cleaner is not available, a soft non-metallic bristle brush may be used. In either case, the tool should be applied in the direction of the fins. Coil surfaces can be easily damaged (fin edges bent over) if the tool is applied across the fins

Use of a water stream, such as a garden hose, against a surface loaded coil will drive the fibers, dirt and salts into the coil. This will make cleaning efforts more difficult. Surface loaded fibers must be completely removed prior to using low velocity c

Quarterly cleaning is required to maintain warranty coverage and is essential to maintain the life of an E-coated coil. Coil cleaning shall be part of the unit's regularly scheduled maintenance procedures.

Failure to clean an E-coated coil on the prescribed quarterly cycle will void the warranty and may result in reduced efficiency and durability in the environment.

A routine two-step quarterly coil cleaning is required to maintain warranty.

Step one is to clean the coil with the below approved coil cleaner (see approved products list under the "Recommended Coil Cleaners” section.

Step two is to use the approved salt/chloride remover under the "Recommended Chloride Remover” section to dissolve soluble salts and revitalize the unit.

It is very important when cleaning and/or rinsing not to exceed 130°F and potable water pressure is less than 100 psig to avoid damaging the unit and coil fin edges.

Failure to clean an E-coated coil will void the warranty and may result in reduced efficiency and durability.

CAUTION! Harsh chemicals, household bleach, or acid cleaners should not be used to clean outdoor or indoor e-coated coils. These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the E-coating. If there is dir

For routine quarterly cleaning, first clean the coil with the below approved coil cleaner. After cleaning the coils with the approved cleaning agent, use the approved chloride remover to remove soluble salts and revitalize the unit.

Recommended Coil Cleaner – Step 1

GulfCoatTM Coil Cleaner, assuming it is used in accordance with the manufacturer's directions on the container for proper mixing and cleaning, has been approved for use on

Never use any cleaners that are not approved.

Recommended Chloride Remover – Step 2

Concentrate, assuming it is used in accordance with the manufacturer's directions on the container for proper mixing, has been approved for use on Ecoated coils to remove chlorides/salts & sulfates.

Never use any chloride removers that are not approved.

Warranty Protection – Step 1

Complete the coil cleaning following these steps:

Ensure that the power to the unit is off and locked out

Clean the area around the unit if needed to ensure leaves, grass or loose debris will not be blown into the coil.

Remove panels or tops as required gaining access to the coil(s) to be cleaned.

Using a pump up sprayer, fill to the appropriate level with potable water and add the correct amount of approved cleaner as per manufacture instructions leaving room for the pump plunger to be reinserted.

NOTE: Coils should always be cleaned / back flushed, opposite of airflow to prevent impacting the dirt into the coil.

If the coils have heavy dirt, fibers, grass, leaves etc. on the interior or exterior face areas, a vacuum and brush should be used to remove those surface contaminants prior to applying cleaner. The interior floor, drain tray or pan areas should also be v

Apply the mixed cleaner to coil surfaces using a pressurized pump up sprayer maintaining a good rate of pressure and at a medium size nozzle spray, (not a solid stream and not a wide fan but somewhere in the middle). Work in sections/panels ensuring that

Apply the cleaner to unit interior air exiting side coil surfaces first. Work in sections/panels moving side to side and from top to bottom

Generously soak coils by spraying cleaner directly on and into the fin pack section to be cleaned and allow the cleaning solution to soak for 5 to 10 minutes.

Using pressurized potable water, (<100 psi), rinse the coils and continue to always work in sections/panels. Start at the top of the coil and slowly move vertically downward to the bottom.

Then, staying in the same vertical area, slowly move back up to the top where you started. Now move over slightly overlapping the area just completed and repeat above. Continue until all coil areas on the inside of the unit have been rinsed

Complete steps 5-9 for the exterior air entering side of the coils.

Final rinse – Now complete a quick rinse of both sides of the coil including the headers, piping, ubends and hairpins.

If the coil has a drain pan or unit floor that is holding rinse water or cleaner, extra time and attention will need to be taken in those areas to ensure a proper rinse has been completed.

Warranty Protection – Step 2 Complete the coil chloride (salt) removal following these steps:

CHLORRID® is a concentrate to be used for both normal inland applications at a 100:1 mix ratio OR for severe coastal applications 50:1 mix ratio with potable water, (2.56 ounces of Chlorrid to 1 gal of water).

Using a pump up sprayer, fill to the appropriate level with potable water and add the correct amount of CHLOR*RID® salt remover leaving room for the pump plunger to be reinserted

Apply CHLOR*RID® to all external coil surfaces using a pressurized pump up sprayer maintaining a good rate of pressure and at a medium size nozzle spray, (not a solid stream and not a wide fan but somewhere in the middle). Work in sections/panels ensuring

Generously soak coils by spraying CHLOR*RID® directly on and into the fin pack section. Let stand for 5 to 10 minutes keeping the area wetted. Do not allow to dry before rinsing.

Using pressurized potable water, (<100 psi), rinse the CHLOR*RID® and dissolved chlorides/salts off of the coils continuing to always work in sections/panels.

Starting at the top of the coil, begin rinsing the coil from side to side until you reach the bottom. Repeat as many times as is necessary to ensure all coil sections/panels have been completed and are thoroughly rinsed

Reinstall all panels and tops that were removed.

Microchannel Coil Cleaning

Air-cooled heat exchangers may include microchannel coils

Cleaning microchannel coils is necessary in all locations. In some locations it may be necessary to clean the coils more or less often than recommended.

In general, a condenser coil should be cleaned at a minimum of once a year. In locations where there is commonly debris or a condition that causes dirt/grease build up it may be necessary to clean the coils more often.

Proper procedure should be followed at every cleaning interval. Using improper cleaning technique or incorrect chemicals will result in coil damage, system performance fall off, and potentially leaks requiring coil replacement.

Documented routine cleaning of microchannel coils with factory provided ecoating is required to maintain coating warranty coverage.

Use the E-Coated Coil Cleaning section for details on cleaning ecoated coils.

Field applied coil coatings are not recommended with microchannel coils

Allowed Chemical Cleaners and Procedures

AAON recommends certain chemicals that can be used to remove buildup of grime and debris on the surface of microchannel coils.

These chemicals have been tested for performance and safety and are the only chemicals that AAON will warrant as correct for cleaning microchannel coils.

There are two procedures that are outlined below that will clean the coils effectively without damage to the coils

Use of any other procedure or chemical may void the warranty to the unit where the coil is installed. With all procedures make sure the unit is off before starting.

WARNING! Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

The water pressure used to clean should not exceed 140 psi, from no closer than 6 inches from the coils, and with the water aimed perpendicular to the coils.

Simple Green

Simple Green is available from AAON Parts and Supply (Part# T10701) and is biodegradable with a neutral 6.5 pH. Recommendation is to use it at a 4 to 1 mix. Use the following procedure.

Rinse the coil completely with water. Use a hard spray but be careful not to bend or damage the fins. A spray that is too hard will bend the fins. Spray from the fan side of the coil

With a pump sprayer filled with a mix of 4 parts water to one part Simple Green spray the air inlet face of the coil. Be sure to cover all areas of the face of the coil.

Allow the coil to soak for 10-15 minutes

Rinse the coil with water as in step one

Repeat as necessary.

Water Flush

This procedure can be used when the only material to cause the coil to need cleaning is debris from plant material that has impinged the coil face.

Rinse the coil completely with water. Use a hard spray but be careful not to bend or damage the fins. A spray that is too hard will bend the fins. Spray from the fan side of the coil.

Spray and rinse the coil from the face.

CAUTION! Use pressurized clean water, with pressure not to exceed 140 psi. Nozzle should be 6” and 80° to 90° from coil face. Failure to do so could result in coil damage.

Application Examples

The two procedures can be used to clean microchannel coils. They will fit with the application depending on the area. In some areas where the spring/summer has a large cottonwood bloom #2 might work fine if the unit is installed on an office building and

Generally the best and broadest based procedure is #1. The grease cutting effect of the Simple Green is good for restaurant applications.

Other Coil Cleaners

There are many cleaners on the market for condenser coils. Before using any cleaner that is not covered in this section you must get written approval from the AAON warranty and service department.

Use of unapproved chemicals will void the warranty. AAON testing has determined that unless a chemical has a neutral pH (6-8) it should not be used.

Beware of any product that claims to be a foaming cleaner. The foam that is generated is caused by a chemical reaction to the aluminum fin material on tube and fin coils and with the fin, tube, and coating material on microchannel coils.

Microchannel coils are robust in many ways, but like any component they must be treated correctly. This includes cleaning the coils correctly to give optimal performance over many years.

Roofing

The cleaning procedures outlined here use relatively benign ingredients.

When working with a rooftop unit care should be taken to make sure the chemicals will not adversely affect the roof coating.

Checking with the roofing supplier/manufacturer is the best way to proceed. If the roofing supplier/manufacturer is not available testing of the chemicals on the roof coating is recommended.

Commercial roofing material manufacturers using PVC and EPDM have been contacted and indicate that there should be no problem with any of the procedures outlined above.

Supply Fans

WARNING! Electric shock hazard. Shut off all electrical power to the unit to avoid shock hazard or injury from rotating parts.

CAUTION! Blower wheels and bands must be inspected for excessive dust build up periodically and cleaned if required. Excessive dust build up on blower wheels may cause an unbalanced state; leading to vibration and/or component failure. Damages due to exce

Lubrication

All original fan motors and bearings are furnished with factory lubrication. Some applications will require that bearings be relubricated periodically. The schedule will depend on the operating duty, temperature variations or other severe atmospheric cond

Bearings should be re-lubricated when at normal operating temperatures, but not running. Rotate the fan shaft by hand and add only enough grease to purge the seals. DO NOT OVERLUBRICATE.

Recommended greases are:

SHELL OIL - DOLIUM R

CHEVRON OIL - SRI No. 2

TEXACO INC. - PREMIUM RB

Removal (6-25 and 30 tons)

Remove fan access panel. Panel is attached with eight 3/8” bolts.

Remove the wire connections from Auxiliary Limit Switch (if applicable) which is mounted in the brace at the fan opening

Remove the brace located at the fan opening.

Remove the six bolts that connect the motor mount to the blower frame. Two bolts are on the angle on the back of the motor mount box, two are on the bottom inside the motor mount box and two are on the inside front of the motor mount box.

Figure 54 - 9-25 and 30 ton Supply Fan

Figure 55 - Bolts which Connect Motor Mount to Blower Fan

Slide the motor mount back away from the air inlet, so that the blower wheel is clear of the inlet. A screw driver or crowbar can be used to help accomplish this. Use the pry slots on the back side of the motor mount.

Pull the motor mount to the edge of the blower frame at the opening.

Remove the motor mount with the motor and blower wheel attached. Large motors will require more than one person.

Care must be taken not to damage the compressors or refrigerant lines when removing the motor and fan assembly.

Power Exhaust Motor and Belt Removal

Remove the four bolts holding the motor mount. There are rivet nuts on the backside.

Remove the belt tensioner bolt completely, as indicated by the arrow below.

At this point the motor mount can be slid toward the wheel, and the belt can be removed.

Once the belt is removed the motor and mount can be lifted out. Make sure the wires to the motor are loose.

Phase and Brownout Protection Module

The DPM is a Digital Phase Monitor that monitors line voltages from 200VAC to 240VAC 1ɸ and 200VAC to 600VAC 3ɸ. The DPM is 50/60 Hz self-sensing. DPM should be wired according to unit specific wiring diagram include in the control compartment

When the DPM is connected to the line voltage, it will monitor the line and if everything is within the setup parameters, the output contacts will be activated. If the line voltages fall outside the setup parameters, the output relay will be deenergized a

Once the line voltages recover, the DPM will re-energize the output relay after the restart time delay. All settings and the last 4 faults are retained, even if there is a complete loss of power.

DPM Setup Procedure

With the supply voltage active to the module, you can setup all of the DPM’s settings without the line voltage connected.

To change the setpoint parameters use the right arrow key to advance forward through the setpoint parameters and the left arrow to backup if needed. When each parameter is displayed use the up/down keys to change and set the parameter.

After adjustments are made or if no adjustments are made it will take 2 to 4 minutes before the DPM energizes the output relay unless there is an out of tolerance issue with the incoming line voltage.

Recommended Default Set-up

Line Voltage 460VAC, 3Ø

Over & Undervoltage ±10%

Trip Time Delay 5 Seconds

Re-Start Time Delay 2 Minutes

Phase Imbalance 5%

Phase and brownout module may be this type on some products (as seen in the above picture).

No setup is needed with this module version, other than checking that the voltage jumper voltage matches the unit voltage

Source: Aaon