Should a 13,500 BTU A/C be wired to a 15 or 20 amp breaker?

[jayspi]

Hi everyone, we bought a 2004 Colorado 5th wheel last year. We've had problems with the A/C not blowing as hard as we think it should, and the circuit breakers (mostly the main, but also the one for the A/C) tripped more and more. The A/C was replaced last year. It is 13,500 BTU and the rig is 30 amp.

The circuit breaker it's on is a 15/20 duplex 2 pole Eaton Cutler-Hammer. The other circuit on that breaker is labeled "General Purpose", and seems to control all of the outlets in the RV that are not GFCI. The microwave and hot water heater are on their own circuits.

I got around to replacing the breakers today and noticed that the listing on the panel said that the A/C is on the 20 amp circuit, but when testing it I found that it was actually connected to the 15 amp.

This is an old RV so I'm thinking that the previous owner might have replaced the circuit breaker at some point and reconnected it improperly. However, the panel could also be labelled incorrectly.

When I reconnected it I put the A/C on the 20 amp and so far so good. Nothing has tripped and the A/C is blowing noticeably harder. I'm wondering though if that was a mistake. What do you guys think? Does it make sense for the A/C to be on 15 amp or 20 amp?

Thanks!

[wnjj]

jayspi wrote:
Our main and A/C breakers are noticeably warm to the touch when it's hot outside. Note that they're just warm now, not hot. They were almost too hot to touch before I replaced them.

There’s the answer to why it wasn’t cooling as well. Heat in the overloaded 15A breaker meant a voltage drop there. A voltage drop meant your compressor wasn't working as well as it should and adding some additional heat to the mix.

[jayspi]

pianotuna wrote:
Hi,

You did tighten all the screws on the buss bar(s) and breakers?

I tightened them all on the breakers but not the buss bars. That's a good idea.

[pianotuna]

Hi,

You did tighten all the screws on the buss bar(s) and breakers?

jayspi wrote:
Our main and A/C breakers are noticeably warm to the touch when it's hot outside. Note that they're just warm now, not hot. They were almost too hot to touch before I replaced them.

Just to be safe, I pulled the whole panel and checked all the wiring. There's no sign of scorching, burning, melting, etc. We also haven't had any trips since replacing them, even when the DW runs the dryer while the A/C is on.

I don't think it's dangerous, I just think they run warm.

[jayspi]

j-d wrote:
Let me say at the git-go, I really don't like the two-breakers-in-one design. Just can't convince me that they don't have more heat buildup than single breakers would have, making it easier to trip falsely.

I agree with you on the heat buildup. Our main and A/C breakers are noticeably warm to the touch when it's hot outside. Note that they're just warm now, not hot. They were almost too hot to touch before I replaced them.

Just to be safe, I pulled the whole panel and checked all the wiring. There's no sign of scorching, burning, melting, etc. We also haven't had any trips since replacing them, even when the DW runs the dryer while the A/C is on.

I don't think it's dangerous, I just think they run warm.

[jayspi]

Roadpilot wrote:
Good advice above. I'd ask though how the size of the breaker could make "the AC not blow as hard". I can understand the breaker tripping, since it's either working or tripped, but not affecting how hard it blows.

Well, I'm not an electrician (obviously!) but what I read on some other sites is that when the motor can't draw enough power it starts to reduce the efficiency of the A/C. That makes sense, but thinking it through, we can run the A/C fan on 12 volt with no shore power, so I don't think that has anything to do with the breaker.

It could have been the placebo effect, or maybe the A/C is able to produce colder air now and I mistook that for it blowing harder.

Either way, there's a real difference in the temperature now. We have a 3 month old so we have 2 thermometers inside. Every night it was up to 75 degrees when we put him to bed and now it's about 70. Outside temps have been the same.

[kmb1966]

red31 wrote:
dometic calls Model 15K Btu

https://www.dometic.com/en-us/us/products/climate/air-conditioners/air-conditioners-for-rvs/dometic-...

Cooling capacity (ISO 5151) Hi Efficiency W
Power consumption - Cooling mode (ISO 5151) 1316 W

There is some confusion on this. I know the model that I have does not have a heatpump, and that model shows that it does, although does show the B59530 model #. I do wish I had a heat mode on mine.

[red31]

dometic calls Model 15K Btu

https://www.dometic.com/en-us/us/products/climate/air-conditioners/air-conditioners-for-rvs/dometic-...

Cooling capacity (ISO 5151) Hi Efficiency W
Power consumption - Cooling mode (ISO 5151) 1316 W

[kmb1966]

Before I purchased my unit, I contacted Dometic tech support because I could not determine what the BTU rating based on the documentation. They said that it was a 13.5k. A few websites show this unit as 13.5k, but most like Camping World, do not indicate it. I use this rooftop unit as a 'backup' or compliment to my current basement a/c. It works wonderful. If it is in the 80's, I can use only this unit very easily. But in HOT Arizona summer of 115 degrees, it works great in conjunction with the basement air. It does not have a heat pump or heat strip though. 😞

This is the unit for sale at Camping World:
Dometic Brisk Air HE

[dougrainer]

Bobbo wrote:

kmb1966 wrote:
Ok. I think this is the installation manual for the Dometic Brisk Air HE (High Efficiency) Unit. I have this unit installed and have been using it for a couple years. On a 15amp circuit. Never trips the breaker. Dometic indicates it to be installed on a 15 amp circuit.
Dometic Brisk Air High Efficiency

So, it does. I sit corrected.

The website here:

https://www.manualslib.com/manual/1061939/Dometic-541815.html?page=4#manual

lists the 3.5kw units as 20 amp and the 2.5kw units as 15 amp. Under "nominal capacity" it lists neither 15,000 BTU nor 13,500 BTU. It lists as "N/A." (They even have some 20 amp units listed as 11,000 BTU.)

On some of Dometic's "models", they could NOT get a 15k BTU rating. They fell short of 15k so they dropped the actual BTU rating and stated "HE". They are close enough to 15k, but are NOT really 15K. They developed those 2 models for the Class B van market where they install smaller Onan 2.5kw gensets. Doug

[Bobbo]

kmb1966 wrote:
Ok. I think this is the installation manual for the Dometic Brisk Air HE (High Efficiency) Unit. I have this unit installed and have been using it for a couple years. On a 15amp circuit. Never trips the breaker. Dometic indicates it to be installed on a 15 amp circuit.
Dometic Brisk Air High Efficiency

So, it does. I sit corrected.

The website here:

https://www.manualslib.com/manual/1061939/Dometic-541815.html?page=4#manual

lists the 3.5kw units as 20 amp and the 2.5kw units as 15 amp. Under "nominal capacity" it lists neither 15,000 BTU nor 13,500 BTU. It lists as "N/A." (They even have some 20 amp units listed as 11,000 BTU.)

[kmb1966]

Ok. I think this is the installation manual for the Dometic Brisk Air HE (High Efficiency) Unit. I have this unit installed and have been using it for a couple years. On a 15amp circuit. Never trips the breaker. Dometic indicates it to be installed on a 15 amp circuit.
Dometic Brisk Air High Efficiency

[kmb1966]

dougrainer wrote:

kmb1966 wrote:

dougrainer wrote:
ALL RV Roof top AC units the install instructions require a minimum of a 20 amp breaker and Minimum 12 /2 Romex wire. Doug

Except the Dometic BriskAir2 H.E. unit.
I have one and the specs on it call for a 15amp breaker. It's the only one I know of that specs a 15 amp instead of 20.

Please try to post that spec. I have never seen a 15 amp breaker listed for a Dometic AC unit. I also have a "Master" spec guide for Dometic AC units, and ALL list a minimum of 20 amp breaker. Doug

http://www.rvpartscountry.com/Dometic13500DuoThermBrisk2TopUnitOnlyAirConditioner.html?gclid=EAIaIQo...

The Model https://www.campingworld.com/brisk-ii-he-air-conditioner-white
on the Camping World Site and RVpartscountry website both show this unit for a 15 amp circuit.
I have the installation manual in PDF, and it shows 15amp, trying to figure out how to post this for information on this site.
It is a DOMETIC MODEL B59530.XX1C0

Trying to figure out how to post the link.

[dougrainer]

kmb1966 wrote:

dougrainer wrote:
ALL RV Roof top AC units the install instructions require a minimum of a 20 amp breaker and Minimum 12 /2 Romex wire. Doug

Except the Dometic BriskAir2 H.E. unit.
I have one and the specs on it call for a 15amp breaker. It's the only one I know of that specs a 15 amp instead of 20.

Please try to post that spec. I have never seen a 15 amp breaker listed for a Dometic AC unit. I also have a "Master" spec guide for Dometic AC units, and ALL list a minimum of 20 amp breaker. Doug

http://www.rvpartscountry.com/Dometic13500DuoThermBrisk2TopUnitOnlyAirConditioner.html?gclid=EAIaIQo...

[kmb1966]

http://www.rvpartscountry.com/Dometic-Brisk-Air-2-High-Efficiency-Air-Conditioner-Top-Unit-Only_p_27182.html

Depends on the model. The one I purchased clearly states 15amp.