Daikin vrv III

[Stevo1978]

Hiya Guys

I know this is a long shot but i dont really have any other info as this is a work collegue who has been to this job and i will be going back with him next week.

All i know is that he had 3 condensing units teed together X3. 2 are the same and 1 is smaller.

When all indoors are set in cool lowest setting and definatley in demand.

Correct me if im wrong but the inverter compressor starts on the 1st unit then the 2nd and then the 3rd and then the same sequence with the fixed speed compressors.
He said the first day he went he could only get the both compressors of the first unit to run and when he returnrd the 2nd day both compressors on the 2nd unit were running.
He has been through all the wiring between the ootdoors and has set up the outdoors with daikin over the phone but is still having problems.

I know i havent give any in depth info but anyone able to give us any pointers

Cheers

Steve

[Brian_UK]

I haven't worked on these units at all so my comments may be thrown out as incorrect but here they are anyway..... ;)

I would expect the load to be increased in this sort of format----
1 Inverter - low load etc
2 Inverter 100%
3 Fixed speed + inverter at low
4 Fixed speed + inverter at max
5 Fixed speed + next fixed speed + inverter at min
6 Fixed speed x 2 + inverter at max
etc to build up load in stages

To load up all the inverters and then to begin staging the fixed speeds would mean shutting down the inverters as the fixed speeds took up the load. They would then stage up again.

I'll sit in the corner now....

[Thermatech]

On the very old vrv systems there was a pipe length dip switch on the outdoor units.
long - medium - sort.
This setting just adjusted the target suction pressure/temp for the length of pipe connected.
With a long pipe length to the indoor units connected there is a larger pressure drop from the indoor units to the outdoor unit along the suction pipe.
But the system can only measure the suction pressure at the outdoor unit & so it must estimate the pressure drop. The engineer had to tell the system if the pipe lenght was short - med - long & the outdoor unit then sets a lower target pressure for the longer pipe length to compensate for the long pipe length & larger pressure drop.

Now you have to set up on the outdoor units with the flashing led's in Set mode 2 for high medium & low target suction pressure & then high - med - low target condensing temperature.

The factory setting is for meduim pipe length.

If you have not done this before you will need to sit down with the service manual & read it through a few times to get it straight in your head first before you attempt to set it up.

However if you have very long pipe lenght to the indoor units & the unit is set for factory meduim suction target pressure then that will result in the outdoor rig not fully ramping up because the outdoor unit is only ramping up to reach the meduim pressure target.

I hope that all makes some sense.

[Refrigerologist]

I haven't worked on these units at all so my comments may be thrown out as incorrect but here they are anyway..... ;)

I would expect the load to be increased in this sort of format----
1 Inverter - low load etc
2 Inverter 100%
3 Fixed speed + inverter at low
4 Fixed speed + inverter at max
5 Fixed speed + next fixed speed + inverter at min
6 Fixed speed x 2 + inverter at max
etc to build up load in stages

To load up all the inverters and then to begin staging the fixed speeds would mean shutting down the inverters as the fixed speeds took up the load. They would then stage up again.

I'll sit in the corner now....

Give that man a biscuit!

[The Viking]

Steve,

It's slightly more complex than that I'm sorry to say.

As far as I'm aware there isn't any fixed running order but rather the control system will do what it wants to do......trying to balance things out.

Also be aware that a system of that size will take an awful long time to ramp up to 100% duty, could be as much as an hour.

Best thing to do is to get a service checker on it.

[Brian_UK]

Give that man a biscuit!Thank you, please make it a chocolate one ;)

[puddleboy3]

On the very old vrv systems there was a pipe length dip switch on the outdoor units.
long - medium - sort.
This setting just adjusted the target suction pressure/temp for the length of pipe connected.
With a long pipe length to the indoor units connected there is a larger pressure drop from the indoor units to the outdoor unit along the suction pipe.
But the system can only measure the suction pressure at the outdoor unit & so it must estimate the pressure drop. The engineer had to tell the system if the pipe lenght was short - med - long & the outdoor unit then sets a lower target pressure for the longer pipe length to compensate for the long pipe length & larger pressure drop.

Now you have to set up on the outdoor units with the flashing led's in Set mode 2 for high medium & low target suction pressure & then high - med - low target condensing temperature.

The factory setting is for meduim pipe length.

If you have not done this before you will need to sit down with the service manual & read it through a few times to get it straight in your head first before you attempt to set it up.

However if you have very long pipe lenght to the indoor units & the unit is set for factory meduim suction target pressure then that will result in the outdoor rig not fully ramping up because the outdoor unit is only ramping up to reach the meduim pressure target.

I hope that all makes some sense.

Both the VRV II & VRV III calculate there own pipe length during the test period. So there should be no need to adjust this setting.

[frank]

When all indoors are set in cool lowest setting and definatley in demand.

He has been through all the wiring between the ootdoors and has set up the outdoors with daikin over the phone but is still having problems.

Cheers

Steve
Can you tell us what the problems are?

[grub]

Hiya Guys
All i know is that he had 3 condensing units teed together X3. 2 are the same and 1 is smaller.

When all indoors are set in cool lowest setting and definatley in demand.

Correct me if im wrong but the inverter compressor starts on the 1st unit then the 2nd and then the 3rd and then the same sequence with the fixed speed compressors.
He said the first day he went he could only get the both compressors of the first unit to run and when he returnrd the 2nd day both compressors on the 2nd unit were running.
Steve

G'day Steve,

Not entirely sure of the actual problem, but some food for thought.

By the sounds of it 2 larger one smaller multi system, it would be a 34 - 44HP system.

The VRVIII rotate the operation of their outdoor units inverter compressors. For example -


smaller larger unit larger unit
unit
INV STD INV STD1 STD2 INV STD1 STD2

No1 No4 No2 No5 No7 No3 No6 No8
No3 No6 No1 No4 No7 No2 No5 No8
No2 No5 No3 No6 No8 No1 No4 No7


Something else to take note is all inverter compressors will start up at the same time and run the same amount of steps to achieve targets sooner however when dropping down in frequency steps they will unload one Inverter at a time. This is something different for the VRVIII multi.