communication wire for Fujitsu mini splits?

[mayhem69]

Hi, i am getting ready to install 2 Fujtisu ductless mini splits model # 15RLS2 (single), and AOU24RXFLZ (dual zone) with 2-7k btu heads.
I have a semi retired hvac guy helping me, i am paying him by the hr. and will save a couple K by doing this.
He states to use 12-2 for the communication wire for the 15RLS2 and use 10-2 for communication wire for the AOU24.
I have read and heard from others 14-3 should be used for the communication wire (from outside to indoor unit).
I want to buy the wire today, so what should i use?
Here are the links to units.
http://m.master.ca/documents/0Fujitsu_Submittal_AOU24RLXFZ.pdf
http://www.fujitsugeneral.com/PDF_06/Submittals/15RLS2 Submittal.pdf

 

[Jackfre]

His wire choice from the disconnect to the condensing unit MAY be right, but from the condensing unit to the evaporators is definitely 14-3. Simple to wire. 1-1, 2-2, 3-3 and ground. 1&2 are the 240 legs. 2&3 form the communication loop between condensing unit and evaporator.

 

[mayhem69]

His wire choice from the disconnect to the condensing unit MAY be right, but from the condensing unit to the evaporators is definitely 14-3. Simple to wire. 1-1, 2-2, 3-3 and ground. 1&2 are the 240 legs. 2&3 form the communication loop between condensing unit and evaporator.

Hi Jack, thanks for the quick response. I am not understanding your terminology because i am a noob with this stuff.
Are you stating i should use 14-3 from the outside unit to the inside unit?

He states to use 12-2 from outdoor unit to the breaker for the 15RLS2, which is 20 amp.
Also said to use 10-2 from outdoor unit to breaker for the AOU24, which is 25 amp.

 

[justsam]

Hi Jack, thanks for the quick response. I am not understanding your terminology because i am a noob with this stuff.
Are you stating i should use 14-3 from the outside unit to the inside unit?

He states to use 12-2 from outdoor unit to the breaker for the 15RLS2, which is 20 amp.
Also said to use 10-2 from outdoor unit to breaker for the AOU24, which is 25 amp.

You are talking about two different wire runs here.

Inside units to outside units both 14/3.

The runs from the breaker or disconnect are the 12 and 10.

I am no expert here but you may want 10/3 and 12/3 from the breaker or disconnect if 120v as well as 240v is required.

 

[mayhem69]

You are talking about two different wire runs here.

Inside units to outside units both 14/3.

The runs from the breaker or disconnect are the 12 and 10.

I am no expert here but you may want 10/3 and 12/3 from the breaker or disconnect if 120v as well as 240v is required.

thanks for your help, that is correct, i understand it is indeed 2 runs, i was told by several hvac techs to use the 12/2 and 10/2 from the outside unit to the breaker.
The confusion was from the outside unit to the inside unit, which you state 14/3, which is what i thought was right.

 

[Tim The Tool Man]

The cost between 10-2 and 12-2 and the cost between 12-2 and 14-2 are not that great, why question it you electrician here? Going with thicker wire can't hurt at all. When I installed my father in law's Fujtisu ductless mini split unit I went with 10-2 and 12-2

 

[JakeKohl]

Hi, i am getting ready to install 2 Fujtisu ductless mini splits model # 15RLS2 (single), and AOU24RXFLZ (dual zone) with 2-7k btu heads.
I have a semi retired hvac guy helping me, i am paying him by the hr. and will save a couple K by doing this.
He states to use 12-2 for the communication wire for the 15RLS2 and use 10-2 for communication wire for the AOU24.
I have read and heard from others 14-3 should be used for the communication wire (from outside to indoor unit).
I want to buy the wire today, so what should i use?
Here are the links to units.
http://m.master.ca/documents/0Fujitsu_Submittal_AOU24RLXFZ.pdf
http://www.fujitsugeneral.com/PDF_06/Submittals/15RLS2 Submittal.pdf

For the AOU24... unit, the manual says 10AWG for the supply and 14awg for the communication (14-3) behind a 25Amp breaker (which leads me to believe you could downsize to 12awg...but would need to see the side-plate info on the outdoor unit to confirm peak amp draw) (page 8)

http://m.master.ca/documents/0Fujitsu_Installation_AOU24RLXFZ_eng.pdf

For the 15RLS2, 12AWG supply and 14 for the comms. (all -3 conductor).

http://www.greendroplet.com/index.php/downloads/dl/file/id/177/fujitsu_9rls2_12rls2_and_15rls2_outdoor_unit_installation_manual.pdf

 

[JakeKohl]

This is interesting - my LG units used a 5 conductor 18awg cable to both power and handle communication from the outdoor unit to the indoor unit. The indoor units did not require an additional supply/disconnect.

 

[Jackfre]

Actually, I believe the NEC requires that a "service switch" be within arms reach of the indoor unit. Some inspectors will catch it, some won't. That switch must be rated for the current of course, so some care must be used in picking it. Fujitsu actually offers one. I did not install them on mine. I think that switch would detract from the very handsome appearance of the evaporators Totally unnecessary...well, depending upon where you have mounted the condensing unit. Mine are wall mounted above a first story roof, so when I pulled a service on my evaps I had to get the extension ladder out to get on the roof to pull the disconnect. That did give me an opportunity to clean the coils on the condensing unit though.