temperzone ISD 950KBX-P Reverse Cycle Ducted Split Systems Instruction Manual

temper zone ISD 950KBX-P Reverse Cycle Ducted Split Systems

GENERAL

• Temperzone ISD/OSA Air Cooled Split Systems.

• Follow these instructions to ensure the optimum performance, reliability and durability.

• Units must be installed in accordance with all national and regional regulations and bylaws. National Health and Safety regulations must be followed to avoid personal

• injuries.
  The appropriate local permits must be acquired and adhered to.

• Local regulations on maximum boundary noise need to be considered when positioning the unit.

• Seismic restraints must be fitted if required.

This appliance is not intended for use by persons (including children) with reduced physical, sensory or mental capabilities, or lack of experience and knowledge, unless they have been given supervision or instruction concerning use of the appliance by a person responsible for their safety. Children should be supervised to ensure that they do not play with the appliance.

INSTALLATION

Indoor unit – ISD

Positioning & Mounting
Line length restrictions between indoor and outdoor unit are given in the Specification sheet.
Clearances for servicing are shown in the Dimension diagrams on the supplied Specifications sheet.
Filter slide rails are built into the return air spigot. Access for filter replacement should be considered.
Mount unit level as drain tray has a built-in slope. Access to fixing centres beneath the return air spigot can be made via the removable bungs in the spigots base.
Flexible duct connections are recommended between the supply and return ducts and the unit.

Drains
Main drain tray drain pipe to be installed as per figure 1 diagram below.

Outdoor Unit – OSA

Positioning

• a. Clearances for optimum airflow and access for servicing are shown in figure 3 and the Dimension diagram on the supplied Specifications Sheet
• b. Consideration should be given to the piping route to the Indoor unit as well as power and control cabling.
• c. The Outdoor unit noise levels need to be considered in respect to boundary noise limits. Change the Outdoor unit position if necessary or erect an acoustic barrier.
• d. If multiple units are to be placed side-by-side then allow at least 2m between coil faces.
• e. Units are designed to be sited outdoors. If siting in a plant room or enclosed space, ensure discharge air is not forced to recirculate back through the coil/s, reducing performance.

Mounting.

• a. For base mounting, fasten the unit to a solid level base using the four mounting points in the feet.
• b. Some commercial rubber pads between the Outdoor unit feet and the base can minimise transmission of vibration.
• c. Units are designed to be sited outdoors. If siting in a plant room or enclosed space, ensure discharge air is not forced to recirculate back through the coil/s, reducing performance.

Drains

The condensate drain pipe to be installed as per figure 1 diagram.
The optional Drain Connection Adaptors 25/13mm (x4) (p/n 060-000-039), can be used to assist in the drainage of water and condensate from the base of the Outdoor unit if necessary. For a totally drip free installation (eg plant room) mount the unit in a separate drain tray.

REFRIGERATION SYSTEM

General

All refrigeration pipe brazing, evacuation and charging shall be performed by a technician with a current Refrigerant Handling Licence.
Hot Work Permits should be acquired where necessary before work commences.
Follow the Refrigerant Handling Code of Practice guidelines.

Piping and Brazing

• a. The Outdoor unit has shut off valves and uses swaged pipe connections. It is shipped with a pre-charge of R410A refrigerant.
• b. The Indoor unit is shipped from the factory with pressured nitrogen.
• c. Immediately before removing the brazed pipe seals from the Indoor and Outdoor units, relieve the pressure to atmosphere after first ensuring the Outdoor unit shut off valves are closed.
• d. Refer to supplied Specification Sheet for pipe sizing.
• e. Use clean sealed refrigeration grade piping designed for R410A.
• f. Before brazing any pipe connections, ventilate the pipe concerned with low pressure nitrogen.
  g. Use pipe cutters to avoid swarf.
  h. Use long radius bends (2x pipe dia.).
  i. Insulate both suction (gas) and liquid lines; seal all insulation joints.
  j. Ensure open pipe ends are sealed until the final connection is made.
  k. If the outdoor unit is to be installed above the indoor unit, then the suction riser should be trapped at the bottom of the vertical rise and then again at 8 m
  (maximum) intervals. This is to ensure oil return to the compressor. The trap should be a ‘swan-neck’ curve in the pipe, with no change in the pipe size.
  Refer figure 2.

Evacuation and Charging

• a. Evacuate Indoor Unit and interconnecting pipework to a vacuum pressure of 500 microns and hold for 15 minutes.

• b. The OSA Outdoor unit is supplied with
  R410A refrigerant sufficient for 10m line length.

• c. Calculate additional refrigerant to suit your line length; refer supplied Specification sheet.

  • Do not exceed the maximum refrigerant charge specified
  • For line lengths less than the pre-charge distance stated above, deduct excess refrigerant at the rate specified, or coil excess pipe out of sight.

• d. If needed, add refrigerant via the Schraeder connection on the smaller of the Outdoor unit’s two service valves. Note: Refrigerant can cause suffocation in high concentrations. Increasing the refrigerant charge, increases the minimum room size to be served by the system. Refer Specification Sheet for minimum floor area. Options to reduce concentration may include: leak detection sensors, forced ventilation, safety shut-off valves and/or overflow rooms.

• e. Record the total amount of refrigerant on the label provided on the electrical box.

• f. Open the service valve at the Outdoor unit to allow refrigerant to flow throughout the system.

• g. For long line lengths, oil (of the correct type) should be added to the refrigerant system at the rate shown in the Specification Data table.

• h. Leak check all brazed and fitted joints.

WIRING

Electrical Requirements

• Electrical power wiring must be fitted and certified by persons with appropriate qualifications and certification.
• A signed electrical ‘Certificate of Compliance’ must be left with the unit for insurance purposes.
• DO NOT install wiring in contact with refrigeration piping. See figures 4 & 5 on page 11 for power wiring and control wiring schematics and positioning.

Power to Outdoor Unit – OSA

• All power wiring is to be done to the appropriate electrical standard of the country in which the unit is being installed.
• The person installing the wiring is responsible for the correct selection of wiring size and auxiliary components.
• See the Specification Sheet for supply voltage range, frequency, phase, maximum operating current and RCD type. Wire the outdoor unit directly from the Electrical Distrib tion Board.
• The unit shall have its own dedicated circuit breaker on the Distribution Board.
• A lockable Isolator Switch shall be fitted adjacent to but not on the outdoor unit (as per AS/NZS 3000).

Power to Indoor Unit – ISD

Three phase mains power wiring to the indoor unit shall be taken from the connection on the outdoor unit. A 24 hour power supply to the compressor crank case heaters is required, otherwise the warranty is void.

Control

Indoor – Outdoor

• a. The Outdoor unit is fitted with a unit controller (UC8) which communicates with an Indoor Unit Controller (IUC) in the Indoor unit.
• b. Communication wiring between indoor and outdoor unit shall be shielded twisted pair cable, wire gauge 22 to 26 AWG (optional Temperzone part).
• c. Communications wiring shall be connected to the indoor and outdoor units as per diagram, refer fig.4 page 6.
• d. It is recommended that communications cabling not be laid directly adjacent to any high voltage 230 or 400 VAC power cables for more than 1m. To minimise signal interference, it is preferable to keep the communication cable at least 300mm away from the mains cable as much as possible and only coming together through wall penetrations and other narrow passages.
• Note: Use the clips provided to keep cables clear of the Gas line.

Room Temperature Controller

Various options are available to control the air conditioning unit operation.

• a. Temperzone TZT-100 Wall Thermostat, which is shown in the ISD/OSA wiring diagrams. It can be wired directly to the indoor unit or the outdoor unit.(Refer to www.temperzone.biz for full features and details; model search ‘TZT-100’. Separate ‘Installer’ and ‘User’ instructions are supplied with the TZT-100 for installation and operation.)
• b. BMS Control via dry contact and analog inputs: both the Outdoor unit controller (UC8) and the Indoor unit controller (IUC) offer facilities to connect a BMS system via a series of no-voltage contacts and 0-10V dc analog signals. Note: 0-10V indoor fan speed control input is only on UC8.
  c. BMS control via Modbus over RS485. For a full list of the Modbus control setup, settings and read/write parameters. Contact Temperzone for details, or visit www.temperzone.biz; model search ‘BMS’.

Refer Section 7.0 for more details on Control settings.

Remote on/off

The UC8 has an input for a remote on/off function on terminal ‘On’, signal return is terminal ‘0V’. When used the remote on/off terminals should connect to a voltage-free relay contact. When not used the remote on/off

terminals should be shorted (‘looped’)

Capacity control

OSA ECO units offer the following capacity control options:

• Automatic control when the unit connects to the
  TZT-100 wall thermostat.

• 0-10V control signal via terminal ‘VC’ on the UC8 circuit board, signal return is terminal ‘0V’.

• Control by a building management system via Modbus RTU or BACnet-IP serial communications.

Unit Controller (UC8)

The temperzone Unit Controller 8 (UC8) is the successor to the UC6 controller. Each dual compressor OSA unit utilises two UC8 Controllers, one for each refrigeration system. The UC8 controllers receive requests such as ‘Unit On/Off’, ‘Start compressors’,
‘Activate HEAT (Reverse Cycle)’ and transfer the requests to the outputs after enforcing safety timers.
The Unit Controller provides several system protection functions. These are covered in Appendix I (p.9).

For additional information, refer to the UC8 Controller label on the unit or www.temperzone.biz for operation & fault diagnostics information; model search ‘UC8’. References available:

• UC8 Operation Manual : Air-to-Air Units
• UC8 Fault & Display Messages (as per unit label) UC8 Quick Reference and Operation Fault Diagnosis UC8 Troubleshooting Guide
• UC8 Modbus Communications
• UC8 BACnet Communications
• UC8 Master-Slave Connection

START-UP PROCEDURE

Before starting the compressor

1. Before working on the unit remove mains power from the unit by opening the mains isolating switch.
2. Remove the shipping blocks from beneath each compressor. Check that each compressor is securely mounted.
3. Check the thermostat and/or other controls are correctly wired to the unit.
4. Check tightness of electrical connections.
5. Check the air filters have been correctly installed, if present.
6. Check that all indoor fan motors can freely rotate.
7. Apply mains power to the unit by closing the mains isolating switch.
8. Check the supply voltage between each phase and neutral.
9. heck air diffusers are open.
10. Before starting the compressors a four hour delay period is required to allow the crankcase heaters to drive any liquid refrigerant out of the compressor oil. Mains power must be switched on during this four hour delay period.

Commissioning

After the four hour delay period has expired (see step 10 in section 5.1) complete the following procedure. You can use the Commissioning Sheet (supplied with the unit) to help you.

1. Place the UC8 master controller in commissioning mode by holding down the SW3 push button on the circuit board (see Section 4.5) until the display shows:
   ‘0’ [release] ‘1’ [long press] ‘t’; [short
   press] repeat to find ‘c’, then [long press] to select. This Commissioning mode ‘c’ reduces the waiting times at start-up and between cycles.for the next half hour, or until the controller is reset by removing power.

2. Start compressor number 1 in cooling mode. Note: Compressors are directional. If a compressor rotates incorrectly it will not pump, be noisy and draw minimal current. If this is the case switch
   the unit off and check for correct mains phase connections at the main power terminals and re-check.

3. Check the outdoor fan motors run smoothly.
   Note: Outdoor fans do not necessarily start rotating immediately after the compressor is started.
   The fans may run-on for a short period after the compressor stops.
   Outdoor fans stop during outdoor coil de-ice cycles.

4. Measure the current draw on each phase to the compressor motor and to each fan motor. Check the readings against the specified values in the wiring diagram or specification sheet.

5. The display and pushbutton on the UC8 can be used to check temperatures and pressures. Short presses on the pushbutton cycles through the available options. Table 1 on page 8 shows, in sequence, what information is available – with examples.
   Alternatively use a set of pressure gauges suitable for R410A refrigerant.

6. Repeat steps 2 to 5 for each compressor.

7. Test operation of the compressors when operating in heating mode.

8. Check for desired supply air flow rate at each outlet.

9. Touch up any outdoor unit paintwork damage to prevent corrosion.

10. Sign the check label.

Commissioning of variable speed (EC) indoor plug fans

A unit equipped with variable speed (EC) indoor plug fans allows adjustment of the fan speeds to obtain the desired indoor supply airflows.
Using TZT-100 option If the unit is controlled with a temperzone TZT-100 wall thermostat then adjustments are made as follows:

1. Stop all compressors. The UC8 display should show a flashing dot (– ●).

2. Hold down the SW3 push button on the circuit board until the display shows:
   ‘0’ [release] ‘1’ [long press] ‘t’; [short press] repeat to find ‘H’, then [long press] to select.
   The indoor fan will start and run at High speed. The display shows the fan control voltage for the Highspeed setting, factory default
   value is 8.0V.

3. Each following button press increases the control voltage in steps of 0.5V. The maximum is 10V. Pressing the button when the maximum of 10V is reached causes the control voltage to step down to the minimum of 3V, where-after subsequent presses once again raise the control voltage in steps of 0.5V.

4. When the desired High speed control voltage is displayed, [long press] to select and save. The controller then exits the menu and the fan stops.

5. from the flashing dot (– ●), hold down the SW3 push button on the circuit board until the display shows:
   ‘0’ [release] ‘1’ [long press] ‘t’; [short press] repeat to find ‘L’, then [long press] to select.
   The indoor fan will start and run at the Low speed setting. The factory default value is 5.0V

6. Repeat steps 3 and 4 to adjust the fan Low speed setting. The minimum control voltage for Low speed is 1V and the maximum control voltage for Low speed is 8V. (Note: A ‘low’ control voltage of less than 2V is not recommended.) If ‘low’ is set higher than ‘high’, the ‘high’ is made equal to ‘low’.

Using Alternative Thermostats Follow same procedure as for TZT-100.
Note:

• If fan speed selections are different from the factory default values then the procedure above must be carried out for each UC8 controller in the unit.

• It is allowed to make the control voltages for low and high fan speed equal. This makes the indoor fan act as a fixed speed fan.

• It is allowed to control the indoor fan speed by an external source, independent of the UC8 controller.

• It is then the responsibility of the system-designer and installer to ensure proper and safe operation of the indoor fan, and the system as a whole, under all operating conditions.
  Setting the indoor fan speed too low can bring risk of frost forming on the indoor coil with potential nuisance frost protection trips on cooling, possibly even unit lock-out, and/or HP trips on heating.
  Setting the indoor fan speed too high can bring a risk of blowing moisture off the fins of the indoor coil and into the supply air duct. Water could then start leaking from the supply air vents and diffusers and corrosion of ducting may occur.

• Setting the indoor fan speed too high can also bring a risk of ‘over-condensing’ (when the unit is heating) which in turn could cause the unit to perform more outdoor coil de-ice cycles than necessary.

OPERATION

Safety timers

The UC8 receives control signals and transfers the signals to the outputs after enforcing safety timers and other protection functions. If the compressor is held off, or held on, by a safety timer then the display shows message ‘H-O-L-d’. Normal durations of safety timers are:

• Minimum off time 3 minutes
• Minimum run time 1.5 minutes
• Min. cycle time 6 minutes (up to 10 compressor starts per hour)
• Min. mode change-over time 10 minutes (cooling to heating or vice -versa)

Variable Capacity

OSA 840/950G units are equipped with two compressors where the first compressor is variable capacity (ie digital scroll type); the second fixed capacity. DIP switch 14 on the UC8 circuit board can be used to select one of two operating modes:

Compressor operating capacities and 0-10V control voltages are:

Note:

• At any time, when operating conditions dictate, safety functions can restrict unit operating capacity.
• Unless the application requires close control it is recommended to operate OSA ECO units in standard capacity control mode.
• When a capacity signal is presented that is lower than the minimum capacity (for example 0V on input ‘VC’) then the compressor operates on minimum duty.
• If a unit operates on low capacity for extended periods then the unit may periodically perform oil flush cycles. Under such operating conditions compressor lubricating oil may slowly settle in parts of the refrigeration system other than the compressor; oil flush cycles help to return the lubricating oil to the compressor. During an oil flush cycle compressor capacity is increased to a certain minimum. The duration of an oil flush cycle is 1 minute.7. Controls

CONTROLS

General
The control details shown in this document relate to the operation of a unit with a single digital compressor (Stage 1: variable capacity controlled) and a fixed capacity compressor (Stage 2: on/off controlled).

TZT-100 wall thermostat
When the unit is controlled with a TZT-100 wall thermostat then it is necessary to configure the UC8 controllers in the unit as a master and a slave. Follow these steps:

1. On the master UC8: DIP switch 11/switch 12 OFF
2. On the slave UC8: OFF DIP switch 11 ON/switch 12 OFF
3. The thermostat connects to the master UC8 as shown below.
4. The Master-Slave communications cable (factory supplied and connected) must stay connected between individual UC8’s (refer wiring schematic sheet 1, grid reference 5-E to 8-E).

To connect the thermostat to the unit it is recommended to use shielded twisted pair type cable, suitable for RS485 communications. Signals A and B should form one twisted pair.

Note: The cable shield should connect to terminal ‘0V’ on the UC8 controller only. Do not connect at both ends. Connect the thermostat as follows:Capacity Staging. A TZT-100 must be configured for two-stage operation.

TZT-100 has its own DIP switches that must be set as follows:

Communications format for TZT-100
Communications format must be set as per recommended Modbus RTU:

• Baud rate (bd or br): 19200
• Data bits: 8
• Parity: Even
• Stop bits (Pa): 1
• TZT-100 address (Ad); 7

TZT-100: The procedure to check and adjust these settings is:

1. Press and hold the O/RIDE button until the display shows the PIN
2. Use the UP & DOWN buttons to select PIN code 88:21, then press O/RIDE in installer mode.
3. Use the O/RIDE and PROG buttons to cycle through the various installer settings.
   If necessary, refer TZT-100 User Manual for more detail.

Control using switched and 0-10V signals

An external controller that provides 24V AC switched signals or has a set of voltage-free relay contacts should be connected as per the diagram below. UC8 inputs ‘VF’ and ‘VC’ will accept a 0-10V capacity control signals. If no capacity control signal is available then link UC8 terminals ‘VF’ and ‘5’ and ‘VC’ and ‘12’.
It is necessary to configure the UC8 controllers in the unit as master and slave; refer Section 7.2 and follow steps 1, 2 & 4.

Control via Modbus RTU communications
OSA ECO units can be fully monitored and controlled via Modbus RTU serial communications. The following is typical for most installations:

• Set DIP switches 11 and 12 OFF on all UC8 controllers.

• Connect BMS terminal A / TX+ to terminal A1 on all UC8 controllers.

• Connect BMS terminal B / TX- to terminal B1 on all UC8 controllers.
  It is recommended to ‘daisy-chain’ the A&B connections using shielded
  twisted pair type cable, suitable for RS485 communications. Signals A and B should form one twisted pair. The cable shield should connect to terminal ‘0V’ on the UC8 controller. The Master/Slave communications cable connected between the UC8 controllers must be removed.
  DIP switch 11 must be set to OFF on both UC8 controllers.

• To avoid collisions of messages on the RS485 serial communications cable it is necessary to ensure each connected UC8 controller has a unique Modbus device address. Refer to section 7.6 for the procedure.

For detailed information about monitoring and control via Modbus RTU refer to document “UC8 Modbus communications”, available free on the temperzone internet website.

Setting the UC8 Modbus device address

To view or change the Modbus device address of a UC8 follow these steps:

• Power up the unit but leave the compressors off.

• Hold down the SW3 pushbutton on the UC8 circuit board until the display shows:
  ‘0’ [release] ‘1’ short press to ‘2,’ [long press] A, [long press]

• The display will show the current Modbus device address. The factory default address is ‘44’. [Short press] the button to select higher numbers, for example press once to change the address to 45, press twice for address 46 and so forth.[Long press] to save the chosen address. After address 99 the number returns back to 1.

• The controller returns to the default state (_●).

MAINTENANCE

WARNING HAZARDOUS VOLTAGE. ENSURE ALL POWER SUPPLIES ARE ISOLATED BEFORE PERFORMING MAINTENANCE. FAILURE TO ISOLATE POWER CAN LEAD TO SERIOUS INJURY.

Monthly

1. Check air filters, if fitted, and vacuum or wash clean as necessary.
2. Check condensate drain for free drainage.
3. Check compressor compartment for oil stains indicating refrigerant leaks.
4. Check system operating pressures via the UC8 (refer Section 5.2.5).

Six Monthly

1. Check the tightness of electrical connections.
2. Check for signs of corrosion on electrical connections in high salt atmospheres; replace where necessary.
3. Check the tightness of all fans, motor mountings
4. Check system operating pressures via the UC8 (refer Section 5.2.5).
5. Check and/or replace indoor air filters
6. Check condensate drain for free drainage.

Yearly

1. Check all refrigerant piping for chafing and vibration.
2. Check the operation of electric heaters, if fitted
3. Check air supply at all diffusers
4. Check for excessive noise and vibration and correct as necessary.
5. Check for insulation and duct damage and repair as necessary.
6. Check system operating pressures via the UC8 (refer Section 5.2.5).
7. Remove lint and dust accumulation from outdoor coil fins with soft brush or low pressure water spray.
8. Touch up any paintwork damage to prevent corrosion.

TROUBLESHOOTING

Room temperature varies significantly from its setting

• Unit may have been incorrectly sized for the building.
• Drafts from wrongly placed supply air diffusers or from the back of the wall plaque could be affecting the temperature sensor built into the wall plaque.
• Poor air circulation in the room can cause incorrect temperature readings.
• If using a BMS, check it has been correctly wired to control the compressor capacity.

Air conditioner does not seem to deliver the heating when most needed

• Heating capacity at design conditions may be incorrect. As the outside temperature falls, heat losses through the walls, floor and ceiling increase.
• Check the unit’s brochure for information on the minimum/ maximum operating temperatures.

When heating, units have de-icing cycles built in to remove ice on the outdoor coil.

• This usually means reversing the cycle for a few minutes during which time there is no heating and in fact a little cooling can occur.

In a new building, why does it take some days before the air conditioning heat hump unit seems to work properly

• Many new buildings, especially a commercial buildings, have a large amount of concrete and other structural materials that are generally cold and full of moisture. This is most evident in the winter when trying to heat the building from scratch.

Unit is leaking water

• Check the drain trap/vent/slope.
• Water carry-over: Reduce the maximum fan speed.

Air conditioner runs excessively – the temperature remains too hot in summer or too cold in winter.

• Windows or doors may be opened to non conditioned areas.
• Keep doors to unconditioned areas closed.
• Leaves, papers or other items blocking air flow over the outdoor unit coil.
• Location of wall controller or remote temperature sensor is incorrect.
• Check for leaks in supply or return air ductwork.

Outdoor unit displays an error code:

• Refer to UC8 Controller label on the unit for operation & fault diagnostics information or visit www.temperzone.biz; model search ‘UC8’.

WARRANTY

Please refer to the separate warranty document supplied with the unit, or visit www.temperzone.biz for details.

New Zealand
customerservices@temperzone.co.nz
Telephone: 0800 TZWARRANTY (899 2777)

Table 1, Information available on the UC8 display.

Suction line pressure 1034 kPa

Evaporating temperature| °C| Et|

Evaporating temperature 12°C

Compressor suction line temperature| °C| SLt|

Suction line temperature 18°C

Compressor suction side superheat| K| SSH|

Suction side superheat 6K

Compressor discharge line pressure| kPa| dLP|

Discharge line pressure 2447 kPa

Condensing temperature| °C| Ct|

Condensing temperature 42 °C

Compressor discharge line temperature| °C| dLt|

Discharge line temperature 70°C

Compressor discharge side superheat| K| dSH|

Discharge side superheat 28K

De-­‐ice sensor temperature  (located on fins of the outdoor coil)| °C| ICEt|

De-­‐ice sensor temperature 39°C

Capacity| %| CAP|

Capacity 100%

Expansion valve 1 opening| %| EE1|

Expansion valve 1 75% open

Expansion valve 2 opening| %| EE2|

Expansion valve 2 75% open

APPENDIX I PROTECTION FUNCTIONS

• • The UC8 implements system protection functions such as indoor coil frost, extreme high and low pressures, rapid on-off cycling of the compressors, loss of refrigerant and more.
• The following applies to all protection functions except where otherwise indicated:
• Unit operating capacity may automatically be reduced before a protection function is activated. Such a reduction may be sufficient to prevent an actual trip from occurring.
• When a compressor is stopped by a protection function it is held off for a period of 3 minutes, after which it is allowed to restart (provided the cause of the trip has cleared).
• When a protection function is active and when a unit is locked out the alarm relay output “FLT” is active.
• More detailed information about protection functions and troubleshooting refer to document “UC8 troubleshooting information”, available for free download from the temperzone internet website.

High pressure protection (HP)

Some OSA ECO units may be fitted with high pressure switches. These switches connect to UC8 inputs IN#1. When a high pressure switch activates (the electrical circuit opens) then the compressor is stopped. Most OSA ECO units are fitted with high pressure transducers connected to UC8 input HPT. A compressor is switched off when the discharge line pressure reading exceeds 4238 kPa.

The display shows the letters ‘HP’ when protection is active.

Low pressure protection (LP)

Some OSA ECO units may be fitted with low pressure switches. These switches connect to UC8 inputs IN#2. When a low pressure switch activates (the electrical circuit opens) then the compressor is stopped.

Most OSA ECO units are fitted with low pressure transducers connected to UC8 input LPT. A compressor is switched off when the suction line pressure reading falls below 228 kPa.The display shows the letters ‘LP’ when protection is active.

Indoor coil frost protection

When the unit is cooling the evaporating temperature in the indoor coil should remain above -8°C. If this temperature falls below -8°C then ice (frost) likely will form on the indoor coil. If the low temperature persists for longer than 6 minutes then the protection function activates. When indoor coil frost protection is activated the compressor is stopped for 6 minutes, after which it is allowed to restart.

High discharge line temperature protection
The controller monitors the compressor discharge line temperature via a sensor connected to input ‘DL’ (red wires). The compressor is stopped when:

• The temperature rises above 110°C for longer than 30 minutes.
• The temperature rises above 120°C (immediate action).

The display shows the message ‘Hi-t’ when protection is active.

High discharge superheat protection
Discharge superheat is defined as the difference between the compressor discharge gas temperature and the condensing temperature. When this temperature differential becomes very high it is an indication that the compressor is being starved of refrigerant gas. Common reasons for this could be a lack of refrigerant (under-charged or loss-of-charge) or a problem with the expansion device (for example a stuck accurator or loose wiring to an EEV).

The protection is activated when discharge superheat exceeds 45K for longer than 30 minutes. The display shows the message ‘Hi-dSH’ when protection is active.

Low discharge superheat protection
Discharge superheat is defined as the difference between the compressor discharge gas temperature and the condensing temperature. When this temperature differential stays very low it can be an indication that the compressor is being flooded with liquid refrigerant. Common reasons for this could be an excess of refrigerant (over-charged) or a problem with the expansion device (for example a stuck accurator or loose wiring to an EEV).

The protection is activated when discharge superheat remains below the threshold for longer than 15 minutes. The threshold varies linearly from 0K at standard mode minimum capacity (40%) to 10K at nominal capacity (100%).This protection function is disabled when a compressor operates at less than standard mode minimum capacity (< 40%).
The threshold for a variable speed compressor operated in boost mode (capacity above 100%) is fixed at 10K.

• The display shows the message ‘LO-dSH’ when protection is active. ****

High evaporation temperature / high suction line temperature protection
When the unit has a low pressure transducer connected to the compressor suction line then the controller calculates the evaporating temperature from the suction line pressure reading. If the unit does not have a low pressure transducer then the controller finds the evaporating temperature via a coil temperature sensor (input IC when the unit is cooling, input OC when the unit is heating, yellow wires). Additionally the controller monitors the compressor suction line temperature via a sensor connected to input ‘SL’ (white wires).
The protection function stops the compressor when:

• The evaporating temperature remains above 27.5°C for longer than 15 minutes.
• The suction line temperature remains above 30°C for longer than 15 minutes.

The display shows the message ‘Hi-SL’ when protection is active.

Other alarms
The controller performs many other protection functions. For example:

• Signals from sensors and transducers must remain inside normal operating range.
• Modbus RTU communications with connected devices (e.g. TZT-100 or SAT-3 thermostat, a Carel Power+ inverter) must continue uninterrupted.
• Modbus RTU communications with a controller such as a BMS that is controlling the unit must continue uninterrupted.

Refer to document ‘UC8 Troubleshooting Guide’ for details.

Lock-out

Each protection function has a trip counter. A trip counter is reset to 0 whenever the compressor run request is removed. Any trip that has occurred more than 12 hours ago is removed from the trip count. For some protection functions, when the trip counter reaches value 3 (i.e. three consecutive trips occur) then the unit is “locked out”.

When a unit is locked out the compressor is not allowed to start. Lock-out is designed to protect the compressor from repeatedly starting when a serious fault exists that requires the attention of a service technician.

The display shows the code of the fault that caused the lock-out condition. A unit that is locked out can be unlocked using any one of the following methods:

• Remove mains power from the unit for at least 3 seconds, then restore power.
• Issue an ‘unlock’ command via Modbus RTU serial communications.
• Reset the controller via Modbus RTU serial communications.

APPENDIX II

AIR HANDLING PERFORMANCE
Note: Airflows are for a dry coil. Reduce airflow by 10% in wet coil conditions. In a free blow or low resistance application, beware of exceeding indoor fan motor’s full load amp limit (refer Specifications document). As filters are optional, the fan air flows given are for units installed without filters.

ISD 840KXY-P
ISD 950KXY-P

CONNECTING ALTERNATIVE THERMOSTATS or BMS

A non-Temperzone alternative thermostat (non-communicating contact switching type) can be connected to:

1. UC8 on the outdoor unit, or
2. IUC on the indoor unit, or
3. A communicating BMS via Modbus over RS485.

NOTE: DO NOT try to connect an alternative thermostat to both the IUC on the indoor unit and the UC8 on the outdoor unit. It is one or the other, not both.

OSA CONNECTION WIRING PATH
Recommended electrical wiring path shown below. Use cable ties supplied. IMPORTANT! Don’t run low and high voltage wiring in parallel; separate where possible. Beware! Potential high temperatures on pipework

• Site Name/address: ………
• Installing Company ………
• Date: …………………………….
• Serviceman: ………………….
• Tel: ………………………………
• Model ………………………….
• Serial No. ……………………..
• Site Ref. ………………………

Mark UC8 dip switch positions with an ‘X’

Record the following UC8 monitored conditions using push button SW3 (repeat to scroll through list). IMPORTANT: Digital compressors must be operating at 100% for at least 10 minutes when taking these readings.

NOTE: This document to be kept with the unit. Failure to provide this completed page on request by Temperzone may effect unit warranty.

References

• Welcome to the temperzone Group Trade website
• Welcome to the temperzone Group Trade website

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