Operating materials
13. April 2021

condensing units Installation instructions

General information and practical tips for using Danfoss OptymaTM condensing units are given below. OptymaTM condensing units represent a complete range of units with hermetic Danfoss reciprocating compressors. The design of this series corresponds to the needs of the market. In general, to give an overview of the program, each subsection is divided into the different hermetic compressors mounted on the condensing units.

General information about handling Danfoss OptymaTM condensing units

General information and practical tips for using Danfoss OptymaTM condensing units are given below. OptymaTM condensing units represent a complete range of units with hermetic Danfoss reciprocating compressors. The design of this series corresponds to the needs of the market. In general, to give an overview of the program, each subsection is divided into the different hermetic compressors mounted on the condensing units.

  1. Danfoss OptymaTM condensing units with the 1-cylinder compressors of the types TL, FR, NL, SC, SC-TWIN and GS: OptymaTM A01 and A04.
  2. Danfoss OptymaTM condensing units with the hermetic 1, 2 and 4 cylinder compressors of the types MTZ and NTZ: OptymaTM A02.

 

 

Furnishing

Danfoss OptymaTM condensing units are supplied with compressor and condenser mounted on rails or base plate. The electrical wiring is done with the help of terminal boxes. In addition, shut-off valves, soldering adapters, collectors, double pressure switches or mains cables with Schuko plugs can complete the scope of delivery. Please refer to the relevant technical Danfoss documentation or the valid price list for details and order numbers. Your local Danfoss sales office will be happy to help you with your selection.

 

 

Power supply and electrical equipment

A01 and A04 These condensing units are equipped with hermetic compressors and fans for 230V-1Ph-50Hz networks. The compressors are equipped with an HST starting device (compressor can start against pressure) consisting of a starting relay and a starting capacitor. These components can also be supplied as spare parts. The starting capacitor is designed for short switch-on cycles (1.7% ED).

In practice, this means that the compressors can be started up to 10 times per hour with a duty cycle of 6 seconds each. OptymaTM A02 condensing units These condensing units are equipped with hermetic compressors and fans for networks with: 400 V-3 Ph-50 Hz for compressors and fan(s) 400 V-3 Ph-50 Hz for compressors and 230 V-1 Ph- 50 Hz for fan(s) - the running capacitor(s) of the fans are mounted in the electrical switch box 230 V-3 Ph-50 Hz for compressors and 230 V-1 Ph-50 Hz for fan(s) - the running capacitor(s) are in electrical control box mounted 230V-1 Ph-50 Hz for compressors - the starting device (capacitor and relays) are mounted in the control box and 230 V-1 Ph-50 Hz for fan(s).

The starting current of the MTZ and NTZ three-phase compressors can be reduced by using a soft starter. CI-tronicTM soft start is recommended for this type of compressor. Depending on the compressor model and the soft starter, the starting current can be reduced by up to 40%. The mechanical stress that occurs during start-up is also reduced, which leads to an increase in the service life of the internal components. If you have any questions about the details of the CI-tronicTM, please contact your local Danfoss sales office.

The number of compressor starts is limited to 6 per hour under resistance starting. HP/LP pressure equalization is required prior to launch when using MCI-C.

 

 

Hermetic compressors

The fully hermetic compressors TL, FR, NL, SC, SC-TWIN and GS have a built-in winding protection switch. When the winding protection is activated, there may be a switch-off time (up to 45 minutes) due to heat accumulation in the motor.

The single-phase MTZ and NTZ compressors are internally protected, depending on temperature and current, by a bimetallic protector that controls the current in the main and auxiliary windings.

The three-phase compressors MTZ and NTZ are equipped with an internal motor protection against overcurrent and overtemperature. The motor protection is located in the star point of the windings and opens all 3 phases simultaneously via a bi-metal disk. After the compressor has switched off via the winding protection, it can take up to 3 hours to switch on again.

If the motor fails, you can use resistance measurement to determine whether the winding protection switch is switched off or whether the winding is broken.

 

 

condenser and fan

The highly effective condensers allow a wider range of applications at higher ambient temperatures. Depending on the capacity, one or two fans are used per condenser unit.

In addition, the fans can be expanded with a Danfoss Saginomiya fan speed controller, type RGE, for example. This allows good condensing control and reduces noise levels. The fans are equipped with self-lubricating bearings, so that many years of maintenance-free operation are guaranteed.

 

 

shut-off valves

provided with shut-off valves on the pressure side. The shut-off valves of the OptymaTM A01 and A04 condensing units are shut off when the spindle is turned clockwise towards the soldering socket. This frees the flow between the pressure gauge connector and the flared connection. If you turn the spindle counterclockwise to the rear stop, the pressure gauge port is shut off. The flow between the soldering piece and the flared connection is free. In the middle position, the flow through the three connections is free. The soldering adapters included help avoid flared connections and make the system hermetic. The shut-off valves of the OptymaTM A02 condensing units are mounted directly in the suction line and on the pressure side of the compressor and receiver. The shut-off valve on the suction side is provided with long straight pipe sockets,

 

 

collector

Liquid receivers are fitted as standard on condensing units for expansion valve operation.

The collectors from an internal volume of 3 l are equipped with Rotolock valves.

 

 

junction box

The OptymaTM A01 and A04 condensing units are electrically pre-wired and equipped with a junction box. This allows the power supply and additional electrical wiring to be connected quickly and easily

The connection box of the OptymaTM A02 condensing units is equipped with terminal blocks, both for the power supply and for the control circuits. The electrical wiring of all components (compressor, fan, PTC, pressure switch) are combined in this box. The electrical circuit diagram is located in the cover of the connection box. This junction box has protection class IP 54.

 

 

high pressure switch

The Danfoss condensing units can be ordered with a combined high and low pressure switch KP17W/B, switchable on the high pressure side. In this way, the pressure monitor or pressure limiter function can be activated. Condensing units that are not supplied with pressure switches from the factory must be fitted with a pressure switch on the high-pressure side in systems with thermostatic expansion valves in accordance with EN 378.

The collectors from an internal volume of 3 l are equipped with Rotolock valves.

The following settings are recommended:

(Observe the maximum permissible operating pressure of the additional components installed in the system.)

refrigerantlow pressure sidehigh pressure side

switch-off point (bar)switch-on point (bar)switch-on point (bar)switch-off point (bar)

R407212125

R404A/R507MBP1.20.52428

R404A/R507 LBP10.12428

R404A/R507 LBP10.12428

R134a1.20.41418

 

 

lineup

The Danfoss OptymaTM condensing units must be installed in a well-ventilated area. It must be ensured that there is sufficient fresh air available for the condenser on the intake side. It must also be ensured that there is no short-circuit flow between fresh air and exhaust air. The fan motor is connected in such a way that the air is drawn in the direction of the compressor via the condenser. For optimal operation of the condensing unit, the condenser must be cleaned regularly.

 

 

weatherproof housing

Danfoss condensing units that are installed outdoors should be fitted with a protective roof or with a weatherproof housing. The scope of delivery optionally includes high-quality weatherproof housings. Please refer to the applicable price list for order numbers or contact your local Danfoss office.

The Danfoss condensing units can be ordered with a combined high and low pressure switch KP17W/B, switchable on the high pressure side. In this way, the pressure monitor or pressure limiter function can be activated. Condensing units that are not supplied with pressure switches from the factory must be fitted with a pressure switch on the high-pressure side in systems with thermostatic expansion valves in accordance with EN 378.

The collectors from an internal volume of 3 l are equipped with Rotolock valves.

 

 

Careful assembly

More and more commercial refrigeration and air conditioning systems are built with condensing units equipped with hermetic compressors. High demands are placed on the quality of the assembly work and the adjustment of such a refrigeration system.

 

 

impurities and foreign particles

Contamination and foreign particles are among the most common causes that negatively affect the reliability and lifespan of refrigeration systems. The following impurities can get into the system during assembly:

  1. Scale formation during soldering (oxidation)
  2. Flux residue from soldering
  3. moisture and foreign gases
  4. Chips and copper residue from deburring the pipes

Therefore, Danfoss recommends the following precautions:

  1. Only cleaned and dried copper pipes and components that meet the DIN 8964 standard are to be used.
  2. Danfoss offers you an extensive
  3. Moisture and foreign gases and a coordinated product range of the required automatic refrigeration. Please contact your local Danfoss office.

 

 

pipe laying

When laying the pipelines, the aim should be to keep the pipeline network as short and compact as possible. Low-lying areas (oil pockets) where oil can collect should be avoided

 

 

Condenser and evaporator are at the same height.

The suction side should be arranged with a slight fall towards the compressor. The maximum permissible distance between the condensing unit and the evaporator is 30 m. To ensure the oil return, the cross-sections listed above are recommended for the suction and liquid lines.

 suction lineliquid line

Outer diameter of copper pipe [mm]

tsp8th6

FR106

NL106

SC108th

SC TWIN1610

GS 211210

GS 341610

 

 

The condensing unit is located above the evaporator.

The target height difference between the condensing unit and the evaporator should not exceed 5 m. The pipeline length should not exceed 30 m. The suction lines are to be designed with double bends as oil traps downwards and upwards. This is done with a U-bend at the bottom and a P-bend at the top of the vertical riser. The maximum distance between the bends is 1 to 1.5 m. In order to ensure the oil return, the following cross-sections are recommended for the suction and liquid lines:

 suction lineliquid line

Outer diameter of copper pipe [mm]

tsp8th6

FR106

NL106

SC 12 and 15108th

All other SC compressors128th

SC TWIN1610

GS 211210

GS 341610

 

 

The condensing unit is located below the evaporator.

The desired height difference between the condensing unit and the evaporator is max. 5 m. The pipe length between the condensing unit and the evaporator should not exceed 30 m. The suction line is to be designed with double bends as an oil trap downwards and upwards. This is done with a U-bend at the bottom and a P-bend at the top of the vertical riser. The max. distance between the bends is 1 to 1.5 m. To ensure the oil return, the following cross-sections are recommended for the suction and liquid lines:

 suction lineliquid line

Outer diameter of copper pipe [mm]

tsp8th6

FR106

NL106

SC128th

SC TWIN1610

GS 211210

GS 341610

 

 

Piping of the condensing units

The connecting pipes should be flexible (jumping in three levels or with anti-vibration mounts). When laying the pipelines, the aim should be to keep the pipeline network as short and compact as possible.

 

 

Low-lying areas (oil pockets) where oil can collect should be avoided. Horizontal lines should be laid falling towards the compressor. In order to ensure oil return, the suction gas velocity in risers must be at least 8-12 m/s.

In the case of horizontal lines, the suction gas speed must not fall below 4 m/s. The vertical pipelines are to be designed with double bends as oil traps at the top and bottom. This is done with a U-bend at the bottom and a P-bend at the top of the vertical pipe. The maximum riser height is 4m unless a second U-bend is fitted.

 

 

If the evaporator is mounted above the condensing unit, it must be ensured that no liquid refrigerant gets into the compressor during the standstill phase. In order to avoid the formation of condensation water and an unintentional increase in suction gas overheating, the suction line must generally be insulated. The suction gas overheating is adjusted individually for the respective application. Further information can be found in the following chapter under “Max. permissible temperatures”.

 

 

leak test

The Danfoss condensing units are already tested for leaks with helium and provided with an inert gas filling at the factory and must therefore be evacuated with the system. In addition, the added refrigerant circuit must be checked for leaks with nitrogen. In this case, the suction and liquid valves of the condensing unit remain closed. The use of colored leak detectors will void the warranty.

 

 

soldering

The Danfoss condensing units are already tested for leaks with helium and provided with an inert gas filling at the factory and must therefore be evacuated with the system. In addition, the added refrigerant circuit must be checked for leaks with nitrogen. In this case, the suction and liquid valves of the condensing unit remain closed. The use of colored leak detectors will void the warranty.

 

 

protective gas

At the high brazing temperatures under the influence of atmospheric air, oxidation products (scale) are formed.

A protective gas must therefore flow through the system during soldering. Pass a gentle stream of dry inert gas through the pipes. This is usually dry nitrogen (N2).

Only start soldering when there is no longer any atmospheric air in the component in question. Start the work process with a powerful flow of protective gas, which you reduce to a minimum when you start soldering. This weak protective gas flow must be maintained throughout the entire soldering process.

Soldering is to be carried out under oxygen and gas with a soft flame. The solder should only be added when the melting temperature has been reached.

 

 

evacuation and filling

The vacuum pump should be able to extract the system pressure to approx. 0.67 mbar and work in two stages if possible.

Moisture, atmospheric air and inert gas should be removed.

If possible, two-sided evacuation from the suction and pressure side of the condensing unit should be provided.

Use the connections on the suction and liquid side stop valves.

 

 

A filling level or filling cylinder or, for smaller condensing units, a scale is used to fill the system. The refrigerant can be supplied as liquid to the liquid line if a charging valve is fitted. Otherwise, the refrigerant must be fed into the system in gaseous form via the suction shut-off valve while the compressor is running (break the vacuum beforehand).

Please note that the refrigerants R 404A/R 507 and R 407C are mixtures. Refrigerant manufacturers recommend that R 507 be charged in liquid or gaseous form, while R 404A and R 407C should be charged in liquid form. It is therefore recommended to top up R 404A/R 507 and R 407C as described using a filling valve.

If the amount of refrigerant to be charged is unknown, charging will continue until bubbles no longer appear in the sight glass. Constant monitoring of the condensing and suction gas temperature is necessary to ensure normal operating temperatures.

Please observe the following procedure for evacuating and filling the OptymaTM A01 and A04 condensing units: For evacuation, both outer hoses are connected to a manifold and the condensing unit is evacuated with the shut-off valves open - the spindle in the middle position.

After evacuation, both hoses (pressure and suction side) are connected to the manifold. Only then is the vacuum pump switched off.

The refrigerant bottle is connected to the center connection of the manifold and the filler neck is briefly vented. The corresponding valve of the manifold is opened and the system is filled via the pressure gauge connection of the suction shut-off valve with the max. permissible refrigerant charge when the compressor is in operation.

 

 

Please note the following recommendation for evacuation and filling

It is recommended to carry out the evacuation as described below:

1. The condensing unit service valves must be closed.

2. After the leak search, a two-sided evacuation should be carried out with a vacuum pump to 0.67 mbar (abs.). It is recommended to use clutch lines with the largest possible passage and to connect them to the service valves.

3. As soon as the vacuum of 0.67 bar (abs.) is reached, the system is disconnected from the vacuum pump. The system pressure must not increase during the next 30 minutes. If the pressure rises quickly, the valve is leaking. A new leak search and evacuation (from 1) must be carried out. If the pressure increases slowly, this indicates that moisture is present. In this case, you should evacuate again (from 3).

4. Open the service valves on the condensing unit and break the vacuum with dry nitrogen. Repeat process 2 and 3.

 

 

General note:

The compressor should not be switched on until the vacuum is broken. When the compressor is operated with a vacuum in the compressor housing, there is a risk of voltage flashover in the motor winding.

 

 

Exceeding the max. permissible operational fill quantity and outdoor installation

Protective measures must be taken if the refrigerant is filled in excess of the max.

Refer to the Danfoss compressor technical information and/or installation instructions for the maximum allowable operating charge levels. If you have any questions, your responsible sales office will be happy to advise you.

The use of a crankcase heater offers a quick and easy solution to prevent refrigerant migration during downtimes.

 

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