Daikin star wired

[ICEmarc]

Could a star wired vrv heat recovery cause transmission faults after 3yrs of being trouble free?

[chemi-cool]

Star or Y wired is about the motor only, regardless to the work it is doing.

Its easier on the motor start torque and pulls less amps then Delta or Δ.

And To your question, nope.

[CraigMac0113]

Could a star wired vrv heat recovery cause transmission faults after 3yrs of being trouble free?
Hi Marc
Do you mean a VRV system wired in a way other than a 'daisy chain' style.
Where you have wiring randomly connected between indoor units and not in sequence?

[Jase]

Strange enough, I would say yes.
I had a 'K' series operating for years which was hooked up to a DBACS. This VRV was added at a later date and the F1/F2 loop was star wired into the DBACS panel as opposed to connecting up to the rest of the daisy chain.
Did get the odd fault appearing but it always reset. In the end I just rewired.

Jase

[ICEmarc]

Hi Marc
Do you mean a VRV system wired in a way other than a 'daisy chain' style.
Where you have wiring randomly connected between indoor units and not in sequence? Exactly what I mean, I have a vrv ii heat recovery system thats been working fine but now keeps going into U9, the wiring is appauling and I'm going to trace it tommorow. If 1 fan coil was isolated by the customer would it create a transmission fault?


Strange enough, I would say yes.
I had a 'K' series operating for years which was hooked up to a DBACS. This VRV was added at a later date and the F1/F2 loop was star wired into the DBACS panel as opposed to connecting up to the rest of the daisy chain.
Did get the odd fault appearing but it always reset. In the end I just rewired.

Jase
Only just taken over maintenance of this system but client states it's never happened before

[multisync]

Star or Y wired is about the motor only, regardless to the work it is doing.

Its easier on the motor start torque and pulls less amps then Delta or Δ.

And To your question, nope.

Chemi

This is related to the wiring of the VRV indoor units for the comms wiring. It is supposed to be daisy chained from one to the next to the last. Occasionally for whatever they wire to a central point and 'star' out like spokes on a wheel to each indoor unit.

although Nike has an interesting comment

http://www.refrigeration-engineer.com/forums/showthread.php?t=3966

page 174 as nike suggests
http://www.daikinac.com/commercial/documents/july07/VRV%20HP%2096&192%20HP_Design,%20Installation%20and%20Testing%20Instruction%20SiUS39-504.pdf

[troymedhurst]

Hi Guys,

In my opinion a U9 fault is generally a transmission error, where one unit has powered down or turned off for some reason. All of the remotes will show U9, which is basically telling you that another unit on the system is in fault.

As to the way the wiring is run, I too was told that it works on resistence of the cable, but then I spoke to daikin technical and was told that it works on what order the indoor pcbs, simply, reply.
Normally any centralised contoller has to be connected to the outdoor, But I know that, on a two pipe system, you can star off of any indoor unit. But if that unit powers down for any reason a fault will occur.
Also I read on the link that was pasted on this tread, that when an addition is added to a vrv or replacement pcb, it will all need re addressing, this is not totally true. If the system has higher form of control i.e centralised controller. The units will not lose their address , you would only have to give any new unit a spare address and re-set system. It does not autmatically re-address. A system will only automatically re address if no higher control is connected to the system.
All of this infomation, I belive to be correct, as from daikin technical
Hopes this helps Troy

[ICEmarc]

Hi Guys,

In my opinion a U9 fault is generally a transmission error, where one unit has powered down or turned off for some reason. All of the remotes will show U9, which is basically telling you that another unit on the system is in fault.

As to the way the wiring is run, I too was told that it works on resistence of the cable, but then I spoke to daikin technical and was told that it works on what order the indoor pcbs, simply, reply.
Normally any centralised contoller has to be connected to the outdoor, But I know that, on a two pipe system, you can star off of any indoor unit. But if that unit powers down for any reason a fault will occur.
Also I read on the link that was pasted on this tread, that when an addition is added to a vrv or replacement pcb, it will all need re addressing, this is not totally true. If the system has higher form of control i.e centralised controller. The units will not lose their address , you would only have to give any new unit a spare address and re-set system. It does not autmatically re-address. A system will only automatically re address if no higher control is connected to the system.
All of this infomation, I belive to be correct, as from daikin technical
Hopes this helps Troy

U9 fault was indeed an isolated indoor unit thanks for pointing me in the right direction

[chemi-cool]

Thanks Rich,
I know I did a good thing when I've stopped touching those air conditioners years ago.

I was referring to regular electric motors with or without frequency controller.