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Both compressors come on when on EITHER 50a or 30a. #2 kicks in apx 2 min after #1 if needed. #1 pulls apx 17a and both running together pull apx 26a so you cannot run other big loads (inc electric water heater) when on 30a service. You can watch amp usage on the one place center when on 30a or on generator. When in 30a in hot weather I sometimes trip the breaker to #2 so we can run the microwave and not have to shut the ac off completely.

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Homeless,

We also have the basement heat pump and love it. Suggest you visit the Airxcel website and download some of there documentation. Lots of info there.

 

http://www.rvcomfort.com/rvp/pdf_documents/1976323a.pdf is the service manual that tells you how it works.

 

As to whether both compressors will run on 30 amp service... As AFCHAP said, yes both will run, BUT your load management system will shut number two off if your trying to pull over the 30 amp limit.

 

Only one compressor will run if the thermostat is set to LESS than two degrees below ambient room temperature. Number two will start (if power available) when the differential is MORE than two degrees.

 

When only one compressor is running on mine the cooling is limited to about 8-10 degrees difference between the return air (fan on high) and the cold air outlet nearest the heat pump. When the second compressor is running the difference is 18-20 degrees. According to the manufacturer that is what is expected.

 

If your having problems there was another thread here a few weeks ago that may be of interest: http://www.rvnetwork.com/index.php?showtopic=120183&hl=

 

I think you were part of the conversation on that one.

 

Also, I (and others) have had issues with the duct work between the basement unit and the ceiling. Mine came apart near the basement unit and was easy to fix. Others have had to remove the rear cap to fix.

 

Lenp

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i also have basement a/c was told need 50 amp for both compressors to come one. as at some point when 2nd one comes on , on the board shows a quick 35amp draw.

past week we finally took out rv out for few days, an 1st time using the brand new basement a/c unit. did great but outside temp was 85 i got unit to 65 degrees.

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When the second compressor is running the difference is 18-20 degrees. According to the manufacturer that is what is expected.

Lenp -- can you give me a reference to that mfg'er info? I've seen it quoted many times in different ways that any ac max performance is 20 degree differential. If that is the case for a normal ac unit, why wouldn't two compressors together do more? My unit definately does better than 20 degrees, although it still won't cool the rig to comfort when outside temps are 110+ with no shade.
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AFCHAP,

Here is a cut & paste of emails between me and Airxcel

MY EMAIL TO AIRXCEL:

 

I have a 6535 installed in my 2002 Winnebago motorhome and have been quite happy with it even though I have had to change an outdoor fan motor and control board. I consider that pretty good performance for nearly 14 years!

I do have a question regarding how much cooling (or heating) I should expect from the unit. We are not the original owners so I do not have a good benchmark for the units performance. We are currently on the Louisiana gulf coast with humidity ranging from 60-85% (outside) and
around 50 inside. When I measure the temperature differential (intake
to outlet) with BOTH compressors running I see a 16 degree difference (I have seen 19-20 in dryer environment). With only one compressor running I see a 9 degree differential.

The unit does a great job until the outside temperature gets into the high 90s. From what I have read on some of the RV forums I see differential temperature expectations all the way up to 40 degrees with both compressors running. I find that very hard to believe but often wonder if it shouldn't a little better than the 16 degrees I am seeing.

Can you please advise if what I am seeing is normal or should I have it checked. I have removed and cleaned the unit thoroughly so I am confident I have good airflow in both coils.

 

AND THERE RESPONSE:

 

 

 

Everything you have found with yours is normal. The ones you are seeing with a 40 degree drop have an issue, or they are running in low fan speed.

The first thing I would look for in your case would be a leak in the supply duct going up the back cap of the RV. If you have a leak in this duct, not all of your supply air will make it back into the coach, which will make it difficult for the AC to keep up with the load when you get into higher temperatures.

The simplest way to check for a leak in the duct would be to have one person laying under the back of the coach, looking up the duct with a flashlight, while a second person turns on the fan of the AC. Once the duct is pressurized by the supply air, you would usually see the leak spread open.

Let me know if you have any questions.



Eric Botts
Technical Assistance Coordinator
RV Products, a division of Airxcel, Inc.
3050 N. St. Francis
Wichita, Kansas 67219
Normal Hours Of Business:
8am – 11:45am CST and 12:45pm – 5pm CST
Office: 316.832.4357
Fax: 316.832.3417
www.Airxcel.com


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Thanks Lenp. That is interesting. I haven't checked in the past couple of years, but I have measured as much as 41 degrees difference on several occasions in the past using an infrared thermometer. We always run on high fan. A meat type probe would perhaps measure differently. When mine gets closer to 20 either the 2nd compressor isn't working or the rear duct is leaking. So I guess my unit "has an issue", but it is an issue I like. :)

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AF,

Is that 41 degrees difference between inside and outside or actual return air to outlet air? I have never tried using infrared thermometer - might try that the next time I am running the AC and see if it measures different from the thermocouple I normally use.

 

Lenp

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We don't try to keep the house that cold, more like 75-80, but I have measured 39 degree output at 80 degrees. That surprised me so I tried again & got the same. Most measurements I have made were a high 30's differential with output in the low 40's.

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We don't try to keep the house that cold, more like 75-80, but I have measured 39 degree output at 80 degrees.

Where the problem comes when you get too great a temperature drop across any air conditioner is that most will start to freeze up at any ∆t that exceeds about 24˚. The reason for them saying that the fan needs to be on high is to prevent it from freezing up. By applying the same amount of cooling but to a higher rate of air flow it removes just as much heat from the inside of the air conditioned space while keeping the cooling coils above the freeze temperature point. I have never fooled with any basement systems but the ∆t range is usually pretty much the same for most other types of air conditioner.

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Thanks Lenp. That is interesting. I haven't checked in the past couple of years, but I have measured as much as 41 degrees difference on several occasions in the past using an infrared thermometer. We always run on high fan. A meat type probe would perhaps measure differently. When mine gets closer to 20 either the 2nd compressor isn't working or the rear duct is leaking. So I guess my unit "has an issue", but it is an issue I like. :)

My basement unit is close to your numbers. Someone told me those numbers were impossible, so I guess both our units are performing an impossible function.

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I just did some measurements with two different thermocouple meters and an infrared gun. Both of the thermocouple meters read 17-18 degree differential. Using the infrared resulted in 27 degree differential.

 

I certainly cannot explain the difference - perhaps someone else here can.

 

Should note I am down here on the Louisiana gulf coast with VERY high humidity. I am going out on a limb and attributing the 17-18 versus 20 or more to the humidity. I have seen closer to 20 in dryer climates.

 

Lenp

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