# 115 volt Mini Split HVAC



## drspec (Sep 29, 2012)

Recently I wired up a 15 amp 115 volt mini split hvac system.

Yesterday I got a call from the hvac installer telling me that the indoor unit pulled an additional load and my 15 amp circuit was tripping.

I always thought that these were sold as a package. 
if the unit is listed at 15 amp max and is tripping the breaker, what would you do?
He wants me to install a 20 amp circuit which I said I cannot do according to the nameplate.


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## BBQ (Nov 16, 2010)

drspec said:


> Recently I wired up a 15 amp 115 volt mini split hvac system.
> 
> Yesterday I got a call from the hvac installer telling me that the indoor unit pulled an additional load and my 15 amp circuit was tripping.
> 
> ...


You are right, you can't exceed the label, there had to be more to this.


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## Dennis Alwon (May 9, 2009)

Is the inside unit a heat pump or a heat pump with heat strips. You may need to feed the inside unit and fuse down to the outdoor unit. There are many configurations for these units. Some have indoor DC motors while others don't and they require line voltage controls while others used low voltage control circuits.


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## drspec (Sep 29, 2012)

Dennis Alwon said:


> Is the inside unit a heat pump or a heat pump with heat strips. You may need to feed the inside unit and fuse down to the outdoor unit. There are many configurations for these units. Some have indoor DC motors while others don't and they require line voltage controls while others used low voltage control circuits.


 
I was waiting on the hvac guy to email me the model #s and system info so I could do my own research but have yet to receive anything from him.

When I met him on the job for the install, I was instructed that all I was required was to wire the outdoor unit and he would do the control wires for the indoor unit. Nameplate stated 15 amp 115 v.

I have wired up many 220v minisplit units in the past and have never had any problems. This is my first experience with a 115v model.

I can say after meeting with the hvac guy, he didn't appear to be playing with a full deck. 

I just want to get paid for this job and am hestitant to harrass the HO if he's having problems with the breaker tripping. You know the hvac guy is already pointing fingers at me.
He was trying to convince me on the phone to install a 20 amp breaker on 14 wire. I kept telling him I couldn't do that and he kept asking me why not.


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## Dennis Alwon (May 9, 2009)

drspec said:


> I was waiting on the hvac guy to email me the model #s and system info so I could do my own research but have yet to receive anything from him.
> 
> When I met him on the job for the install, I was instructed that all I was required was to wire the outdoor unit and he would do the control wires for the indoor unit. Nameplate stated 15 amp 115 v.
> 
> ...


If the system calls for maximum overcurrent protection of 20 amps then you may use a 20 amp breaker on the #14 wire.

The only mini split I hooked up that was 120V got wired 240V -- oops- first one I ever saw and the hvac told me it was the same as the one we just wired for them-- I should have checked.


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## BBQ (Nov 16, 2010)

Dennis Alwon said:


> If the system calls for maximum overcurrent protection of 20 amps then you may use a 20 amp breaker on the #14 wire.


The label is 15 amps.


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## drspec (Sep 29, 2012)

yes, the label says 15 amps.


With what Dennis said I have a question. 
I know with AC you can install a larger breaker on a smaller wire, but with this being an electric heat/ac combination, that would not be compliant would it?
If the nameplate was 20 amps you would have to install 12 gauge or larger. Am I thinking correctly?
I know around here with gas package units, inspectors won't let you install a smaller gauge.


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## RePhase277 (Feb 5, 2008)

How long is the circuit? Voltage drop might be giving you grief.


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## drspec (Sep 29, 2012)

circuit is probably 30' - 40' if that long


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## darren79 (Dec 20, 2011)

drspec said:


> yes, the label says 15 amps.
> 
> 
> 
> ...


If the unit had a MCA below 15A and a max fuse of 20A then you would be able to use #14 on a 20A breaker.


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## Dennis Alwon (May 9, 2009)

drspec said:


> yes, the label says 15 amps.
> 
> 
> With what Dennis said I have a question.
> ...



I see your point but this is a packaged unit iIMO and art. 240.4(G) should apply.

I understand the label says 15 amp I was adding to the post that in some cases you can use 20 amp on 14 wire.


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## RePhase277 (Feb 5, 2008)

So have you actually put an ammeter on the line to watch this thing run? You need to check the amp draw on this thing as it starts and runs, and the voltage at both ends of the line during start up.

If it isn't voltage drop, then the unit is faulty.


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## drspec (Sep 29, 2012)

I haven't been by the house since the HVAC guy called me.
I haven't heard from the HVAC guy or the HO since yesterday either.


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## kbsparky (Sep 20, 2007)

drspec said:


> yes, the label says 15 amps....


What else does the label say? 

There should be 2 values on that label: 

Minimum circuit ampacity
Maximum overcurrent protection.

Which one is 15 Amps?


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## wendon (Sep 27, 2010)

kbsparky said:


> What else does the label say?
> 
> There should be 2 values on that label:
> 
> ...


I agree. If the MOP is 15 amps you can't change that. If the MCA is 15 then it might be okay to install a 20 amp breaker. I would definitely check out the system with an amp meter.


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## Amish Electrician (Jan 2, 2010)

drspec, your info does not add up. Mini-split nameplates do not simply say '15A 115V.'

Let's see a pic of the actual tag. The entire tag. The one on the outside unit.

I'd also like to see a wiring disgram, one that shows the inside unit getting power from the outside unit. 

I didn't know thay made mini-splits that small.


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## TTW (Sep 14, 2012)

Do you remember who the manufacturer is?


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## macmikeman (Jan 23, 2007)

The guy screwed up on the control wiring. Probably reversed two of the three conductors between indoor and outdoor and the machines do not like that.


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## drspec (Sep 29, 2012)

I don't recall the brand of the unit, but it was min 15 amp 115v and max 15 amp 115v. 
I haven't been back to the job nor have I heard from the hvac guy or HO since Monday.
I'm going to call the HO tomorrow about getting paid and see if he mentions anything.


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