Daikin VRV II

[El Padre]

Seasons Greetings to everyone!

I am hoping for some advice regarding a system which comprises of:
1 REYQ16MW1B, 1 REYQ12M8W1B AND 1 REYQ10MW1B ( 1 master and two slaves)

I have yet to attend this site, but the problem that they have had is a leak where all the refrigerant charge has been lost, and according to the site engineer, a considerable amount of oil.

What I would like to do once the leak is repaired and system recharged is: Force the system into an oil recovery cycle (if possible), run all compressors fully loaded simultaneously (again if possible), monitor the oil temperature and if outside of parameters add oil via the oil equalisation line.

Just wondered what the procedure is to perform the above as I have done very little with the VRV II range, I can't remember off hand how to even determine the master unit!

Cheers

[cool#9]

Seasons Greetings to everyone!

I am hoping for some advice regarding a system which comprises of:
1 REYQ16MW1B, 1 REYQ12M8W1B AND 1 REYQ10MW1B ( 1 master and two slaves)

I have yet to attend this site, but the problem that they have had is a leak where all the refrigerant charge has been lost, and according to the site engineer, a considerable amount of oil.

What I would like to do once the leak is repaired and system recharged is: Force the system into an oil recovery cycle (if possible), run all compressors fully loaded simultaneously (again if possible), monitor the oil temperature and if outside of parameters add oil via the oil equalisation line.

Just wondered what the procedure is to perform the above as I have done very little with the VRV II range, I can't remember off hand how to even determine the master unit!

Cheers
Hi El Padre
To recognize the master / slave unit see the state of the H8P green led on each unit:
H8P on= master unit
H8P Blinks= slave 1 unit
H8P off= slave 2 unit
also the orange leds from H1P to H7P are all off on slave 1 and 2, the normal state is H3P lit on master unit.
About the oil ( FVC68D)... it's still a boring problem to estimate the amount and i still don't know how to start an oil recovery manualy...
In France we can get small tank ( 2 lt ) with FVC68D...
At last you can try to run all compressors by the mode 2 / binary set 6+ return / binary set 2+ return, on the master unit..

rgds
cool#9

[El Padre]

Hi Cool#9,

The unit has been electrically isolated, I think that they perform an oil recovery cycle an hour after they have been switched on for the first time, then every 8 hours, I wonder if this is the case when reinstating power to a system that has already been commissioned.

Thanks for your help.

Cheers

[VRVIII]

Hi Cool#9,

The unit has been electrically isolated, I think that they perform an oil recovery cycle an hour after they have been switched on for the first time, then every 8 hours, I wonder if this is the case when reinstating power to a system that has already been commissioned.

Thanks for your help.

Cheers

Hi
When ever mains power has been switched on/off, the system will definitely still perform an oil return after 1~2hrs operation in heating or heat recovery mode (not sure about cooling mode but this may also be the case).
It is also possible to force an oil recovery under certain conditions but think the above method would be the easiest way.




Regarding oil loss:

Your complete system has 3 x inv comps + 4 std comps
Each inverter compressor has 1.9L of oil & each standard has 1.6L of oil.
System total oil volume: (3x1.9) + (4x1.6) = 12.1 litres
Therefore I would worry too much unless you have lost over 1~2L in total, unless you have pipe run length >80m (outdoor to furthest indoor).



Also mode 2 setting 6 will not guarantee that all compressors will operate, this will only force all indoors thermo on. You will also have to set the desired operation mode at the indoor controllers first, I would suggest you select heating mode if you want to operate as many compressors as possible.

Re identifying the master unit:
The system should be installed with largest capacity unit as master and the smallest as slave 2.
IE.
REYQ16M - Master
REYQ12M – Slave 1
REYQ10M – Slave 2

This can be verified by checking the LED’s on each unit as described by Cool#9, the master unit will also be the only one connected to indoors/bs boxes by F1F2 cable (slave units will only have Q1Q2 terminals connected).
.

[El Padre]

Hi VRVIII,

Thanks, I may have been over complicating things regarding the oil loss, out of interest is there a safety feature that protects the system from operating with a low oil charge?

Cheers

[VRVIII]

Hi VRVIII,

Thanks, I may have been over complicating things regarding the oil loss, out of interest is there a safety feature that protects the system from operating with a low oil charge?

Cheers

No, VRVII systems do not have any low oil level protection, but a seized comp will soon let you know :)

Do you know the approx pipe run length of the system, from outdoor to furthest indoor? And the height difference from outdoor to lowest/highest indoor?

Remember the system has max run length of 150m (175 equivalent), max height difference of 50m (40m when outdoor is lower that indoors) and max total piping of 300m. This is all possible with no additional oil.

[El Padre]

Hi,
I see your point, I don't know the site yet but the pipe runs are well within the max. allowable and the outdoor units are two floors above the indoor units.

I have replaced compressors before and whilst investigating the cause of failure have found little or no oil in them (mainly caused by continuous low load operation, poor application etc.), I think that it would be helpful if there was a way of determining system oil levels though, could be picked up on service visits.

Is this something that you have encountered before?

Cheers

[cool#9]

[quote=VRVIII;]It is also possible to force an oil recovery under certain conditions but think the above method would be the easiest way.


Hi VRVIII.
I' d like to know the way, maybe you could send a PM...just know it on old series...
Anyway i totaly agree , knowing we are on the French Riviera here and the mode 2 / binary set 6 is usefull here due to hotest condition...( in cooling mode i mean).
rgds
cool#9

[VRVIII]

Hi,
I see your point, I don't know the site yet but the pipe runs are well within the max. allowable and the outdoor units are two floors above the indoor units.

I have replaced compressors before and whilst investigating the cause of failure have found little or no oil in them (mainly caused by continuous low load operation, poor application etc.), I think that it would be helpful if there was a way of determining system oil levels though, could be picked up on service visits.

Is this something that you have encountered before?

Cheers

Hi Padre,

How did you drain oil from the compressor? This is only possible by drilling the compressor base.
How much oil did you remove? You will normally find 0.9~1.5L, anything <0.5L is a problem.

Operating at lower capacity steps shouldn’t be a problem as the oil return start condition is calculated based on time, oil temp, Te and compressor operating frequencies. However a serious application issue could cause problems.


If the compressor you removed contained <0.5L of oil, I would suggest you check the following:




Has the system been operating in emergency with a module disabled for >1 week?
Does the site have power supply problems or is mains interrupted at night?
Have you checked crank case heaters?
Does outdoor unit continually change mode (heating/heat recovery or cooling/heat recovery) due to installation issue?
Verify oil equalising line service valves are open
Blockage/restriction in oil return line filter/capillary (between oil separators & suction line).
Check for liquid pumping during operation possibly caused by faulty EEV, thermistor or transducer.
Check correct operation of oil equalising solenoid valve (Y2S)
I would say the most common reasons for loosing compressor oil are:
1. Liquid refrigerant in the compressor at start up or liquid returning to compressor during operation.
2. Restriction in oil return line or oil equalizing lines
If you have a service checker, I would suggest you record the operations over a 24 hour period then check the data for any abnormalities.


Also when charging a VRVII system NEVER add liquid refrigerant in the suction or dual purpose discharge/suction line (from a vac or when operating), these units have no suction accumulator.


This can result in compressor damage which isn’t always apparent:

Scroll can be fractured/broken - in some cases the compressor will be down to earth due to broken fragment falling into windings.
The discharge reed valve can be damaged/weakened - Results in compressor over heating and premature failure.
Oil can be lifted/pumped out of compressor at start up.
Liquid refrigerant can also wash oil from top bearing – Results in damage to hardened face of bearing and eventually compressor will seize.
Only ever add the refrigerant into the liquid line, either from a vac or if additional charge is required by using refrigerant add mode (mode 2 setting 20).

[El Padre]

Hi VRV III,

Thanks, upon reading your post I remember that that system was in Emergency mode, not sure how long as I did not attend the first call out (the clients engineer, fortunately), I did drill the bottom of the compressor and there was virtually no oil in there, I now understand why, I have only previously used the emergency mode to test the DOL compressor, its good to know what happens if left in that mode though.

Thanks again and Happy New Year to everyone!

Cheers

[VRVIII]

Hi VRV III,

Thanks, upon reading your post I remember that that system was in Emergency mode, not sure how long as I did not attend the first call out (the clients engineer, fortunately), I did drill the bottom of the compressor and there was virtually no oil in there, I now understand why, I have only previously used the emergency mode to test the DOL compressor, its good to know what happens if left in that mode though.

Thanks again and Happy New Year to everyone!

Cheers

Hi Padre,

There are a couple of points you should be aware of regarding VRVII emergency/back up operation:

Individual unit / Stand alone unit – You can disable per compressor
Mode 2 setting 0 = disable inv comp
Mode 2 setting 19 = disable std comp

Multi Application – You must disable per module (master/slave 1/slave 2), settings to disable per compressor must not be used in multi application.
Mode 2 setting 38 = disable master unit
Mode 2 setting 39 = disable slave 1 unit
Mode 2 setting 40 = disable slave 2 unit

The recommended time limit for all of the above settings is 3 days.

All the best for 2010 :).

[multisync]

Hi Padre,

How did you drain oil from the compressor? This is only possible by drilling the compressor base.
How much oil did you remove? You will normally find 0.9~1.5L, anything <0.5L is a problem.

Operating at lower capacity steps shouldn’t be a problem as the oil return start condition is calculated based on time, oil temp, Te and compressor operating frequencies. However a serious application issue could cause problems.


If the compressor you removed contained <0.5L of oil, I would suggest you check the following:





Has the system been operating in emergency with a module disabled for >1 week?
Does the site have power supply problems or is mains interrupted at night?
Have you checked crank case heaters?
Does outdoor unit continually change mode (heating/heat recovery or cooling/heat recovery) due to installation issue?
Verify oil equalising line service valves are open
Blockage/restriction in oil return line filter/capillary (between oil separators & suction line).
Check for liquid pumping during operation possibly caused by faulty EEV, thermistor or transducer.
Check correct operation of oil equalising solenoid valve (Y2S)
I would say the most common reasons for loosing compressor oil are:
1. Liquid refrigerant in the compressor at start up or liquid returning to compressor during operation.
2. Restriction in oil return line or oil equalizing lines
If you have a service checker, I would suggest you record the operations over a 24 hour period then check the data for any abnormalities.


Also when charging a VRVII system NEVER add liquid refrigerant in the suction or dual purpose discharge/suction line (from a vac or when operating), these units have no suction accumulator.



This can result in compressor damage which isn’t always apparent:

Scroll can be fractured/broken - in some cases the compressor will be down to earth due to broken fragment falling into windings.
The discharge reed valve can be damaged/weakened - Results in compressor over heating and premature failure.
Oil can be lifted/pumped out of compressor at start up.
Liquid refrigerant can also wash oil from top bearing – Results in damage to hardened face of bearing and eventually compressor will seize.
Only ever add the refrigerant into the liquid line, either from a vac or if additional charge is required by using refrigerant add mode (mode 2 setting 20).


I must admit I dump charge VRV's with the correct charge (providing the CCH on for at least 24hrs) from vac in all three lines by heating the cylinder . Once fully charged I leave the unit for 1/2hr or so then turn it on and run.

This seems reasonable as it's better than a power cut which can re-start a system within 15 minutes of power returning?

Surely refrigerant will condense in all three lines on a cold day during a power cut?

[VRVIII]

I must admit I dump charge VRV's with the correct charge (providing the CCH on for at least 24hrs) from vac in all three lines by heating the cylinder . Once fully charged I leave the unit for 1/2hr or so then turn it on and run.

This seems reasonable as it's better than a power cut which can re-start a system within 15 minutes of power returning?

Surely refrigerant will condense in all three lines on a cold day during a power cut?

Ahh, Multi there’s always one that’s got to be awkward :(:p
You should never bomb charge into the suction or dual purpose discharge line, I can guarantee you it will catch you out. As I said the resulting compressor damage isn’t always apparent, but can certainly reduce the compressor life span.

Depending on severity of discharge reed valve distortion/weakening, it may only be possible to identify this when compressor is operating at higher frequencies with a good head pressure. The condition is most apparent when operating at max capacity in heating mode with low ambient temps.


This will have the following affect on a system:

Increased discharge superheat and compressor discharge pipe temps
Unit recognizes high Dsh/Dt and utilizes subcooler circuit as liquid injection, attempting to reduce Dsh.
Unit is unable to reduce Dsh/Dt and forces compressor to reduces freq/speed (high discharge temp limiting function)
Results in system capacity shortage
This will require a service checker to be connected to diagnose this phenomenon, the reed valve condition will continue to deteriorate until the unit is unable to control discharge temp and finally trips on high discharge temp (F3 error code). However this could take several months depending on severity of valve damage and operating conditions.



Liquid pumping can also wash oil from bearings or cause the compressor to lift it’s oil, this can eventually result in compressor seizure but again depends on severity of damage and operating conditions.


Ever time these units switch off they carry out a pump down (residual operation) to purge liquid refrigerant from heat exchangers and gas lines, this is why no accumulator is required. However if a power failure was to occur during operation, it can result in a small amount of liquid condensing in the suction line but the volume of liquid would be much less than bomb charging all 3 lines! Obviously continual power failures during operation would have a detrimental effect on any system.
At the end of the day it only takes a couple of minutes longer to charge a system using the refrigerant add mode (correct method indicated in install manual). This in turn can prevent premature compressor failure, giving the product a bad name due to engineers taking short cuts :).

Happy New Year to you :D:D:D

[multisync]

Walk me through a couple

1/What happens during oil recovery?

I was of the understanding the suction line is flooded with liq refrigerant?

2/A hot building in mid winter.
Outdoor around zero
The condenser is below the evaps.
All on full cooling.
Power trips to the building. remains off for 10 hours
Power is restored

power off:
Would liq continue to feed through the eev's and fill the evaps/suction line till equalisation and condense in the compressors as they cool

Power restored:
Would system have a 15 min delay and restart with liq in various places it shouldn't be??

Just seeking clarification but I certainly will enforce your advice;)

[cool#9]

Walk me through a couple

1/What happens during oil recovery?

I was of the understanding the suction line is flooded with liq refrigerant?

2/A hot building in mid winter.
Outdoor around zero
The condenser is below the evaps.
All on full cooling.
Power trips to the building. remains off for 10 hours
Power is restored

power off:
Would liq continue to feed through the eev's and fill the evaps/suction line till equalisation and condense in the compressors as they cool

Power restored:
Would system have a 15 min delay and restart with liq in various places it shouldn't be??

Just seeking clarification but I certainly will enforce your advice;)
I totaly agree
I think we can do a lot of thing while charging a VRV even by the gas pipe, i never had any faillure due to liquid back if it's done slowly...
During oil return the power consumption increases and higher than nominal values, but the system won't be damaged...
cool#9

[VRVIII]

multisync;172256]
Walk me through a couple
No thanks, you can walk yourself or RTFM :D


1/What happens during oil recovery?

The oil recovery process differs depending on the operation mode prior to oil return, both are done in 3 stages pre oil return/oil return/post oil return. The outdoor operates at fixed preset values for each stage of oil return (see VRVII service manual for details)
Basically all indoor EEV’s are forced open to a preset value (10% if op in cooling mode / 25% if op in heating) allowing oil to be returned form indoor heat exchangers. Keep in mind some indoors may be switched off or thermo off trapping oil in coils & dead piping legs.
When in heating mode the system changes to cooling (6min max), indoor fans are switched off and the residual heat from heat exchanger is used to boil off liquid (similar to a defrost cycle).



I was of the understanding the suction line is flooded with liq refrigerant?
No, it doesn’t :confused:




2/A hot building in mid winter.
Outdoor around zero
The condenser is below the evaps.
All on full cooling.
Power trips to the building. remains off for 10 hours
Power is restored

The above scenario is very very unlikely, all indoors in cooling thermo on with an ambient of 0 C then to top it all off a 10hr power cut occurs :eek:.



power off:
Would liq continue to feed through the eev's and fill the evaps/suction line till equalisation and condense in the compressors as they cool

Liquid could in theory pass through EEV of an indoor that was thermo on when power cut occurred, however the valve opening would be small. I would think most of the refrigerant would be boiled off in heat exchanger due to room temp and equalisation of pressures. Also keep in mind the compressor is insulated and will take a few hours to cool down to ambient temp.




Power restored:
Would system have a 15 min delay and restart with liq in various places it shouldn't be??

Yes this is possible, but the volume of liquid condensing in the suction line would be negligible ;).

[multisync]

I see I am not wise in the ways of the defrost:cool:

I shall seek much wisdom from the one you call VRVII manual :D

[VRVIII]

I see I am not wise in the ways of the defrost:cool:

I shall seek much wisdom from the one you call VRVII manual :D

Ah Multisync,

“He that would perfect his work must first sharpen his tools.”

He that perfects VRV repairs must also RTFM :D:D:D