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Jason1955 · 05-13-2016, 06:19 AM

I'm getting ready to replace the A/C unit on my 1992 Fleetwood southwind 30'. It came with a 13.5k unit and I assume it cooled fine (has not worked since I bought it a few months ago). I'm wondering if I should step up and get the 15k unit or just stick with the 13.5? My motorhome has a 30 amp service and has the 4000w generator. I do use the motorhome to pull my race trailer with so I need to make sure the generator will pull the bigger unit. I guess my question is, is it asking too much to run the 15k on a 30 amp service and a 4000w generator?

Thanks!

jacwjames · 05-13-2016, 07:30 AM

Check the spec's on your old AC unit versus a new one. The newer ones are more efficient and draw less power then older ones. You may be able to upgrade to a 15K and still be using less power.

The 4000 Watt generator should be able to provide 33 amps of power at peak, probably ~27 continuous, which is plenty to run a 15K generator. Your coach probably doesn't have any significant parasitic draw so you should be fine either way.

In the long run it's all about power management. No matter what if you try to run too many appliances you will overload. Learn what the draw is on each appliance and balance to stay under.

TQ60 · 05-13-2016, 07:41 AM

Newer ones often may use same compressor but only have different size heat exchangers.

Reducing variability in parts reduces cost

Newer compressors much better than old ones too.

Look at the spec sheet for current one.

New one likely less amps used than old and larger unit likely less as well.

Last time we looked the difference was too small to cate and the better cooling well worth it.

However newer ones seem to be louder than old so visit a sales yard and take a few ac units for a test drive.

MSHappyCampers · 05-13-2016, 10:16 AM

I would definitely go with the 15K! I had to replace one a couple of years ago and went with the 13.5. BIG mistake!

Kinda reminds me of the commercial "I could'a had a V8"

kvm1970 · 05-13-2016, 10:53 AM

Price wise is only around $100.00 difference between the two.

TQ60 · 05-13-2016, 10:57 AM

Go big

**TonyDi** · 05-13-2016, 11:07 AM

If you plan on being anywhere near hot weather, I'd go for the 15k.

vsheetz · 05-13-2016, 01:12 PM

Go for the 15K unit, IMHO.

Brad Felmey · 05-13-2016, 02:01 PM

I just emerged from this decision as well. My investigations centered upon the Dometic Brisk II Air Conditioner (not heat pump variant) units, which come in 13.5k and 15k BTU versions.

The 13.5k BTU unit has a current draw of 15.3A (110v).
The 15k BTU unit has a current draw of 16A (110v).

The circuit in your RV for the A/C unit is most likely a 20A (it is in mine), with at least 12ga Romex wiring (rated for 20A continuous). Rule of thumb is to stay at 80% or less of a circuit's lowest-rated component, so the 16A of the larger 15k BTU unit is right on the money.

So, my analysis said that there was no problem with electricity supply, the units are physically interchangeable, use the same thermostatic control units, and the price difference is manageable (about $90). For this Texas boy that made the decision to purchase the larger one pretty easy.

MSHappyCampers · 05-13-2016, 02:38 PM

Quote:

Originally Posted by Brad Felmey

I just emerged from this decision as well. My investigations centered upon the Dometic Brisk II Air Conditioner (not heat pump variant) units, which come in 13.5k and 15k BTU versions.

The 13.5k BTU unit has a current draw of 15.3A (110v).
The 15k BTU unit has a current draw of 16A (110v).

The circuit in your RV for the A/C unit is most likely a 20A (it is in mine), with at least 12ga Romex wiring (rated for 20A continuous). Rule of thumb is to stay at 80% or less of a circuit's lowest-rated component, so the 16A of the larger 15k BTU unit is right on the money.

So, my analysis said that there was no problem with electricity supply, the units are physically interchangeable, use the same thermostatic control units, and the price difference is manageable (about $90). For this Texas boy that made the decision to purchase the larger one pretty easy.

Wise decision!

Brad Felmey · 05-13-2016, 04:14 PM

Quote:

Originally Posted by Brad Felmey

I just emerged from this decision as well. My investigations centered upon the Dometic Brisk II Air Conditioner (not heat pump variant) units, which come in 13.5k and 15k BTU versions.

The 13.5k BTU unit has a current draw of 15.3A (110v).
The 15k BTU unit has a current draw of 16A (110v).

The circuit in your RV for the A/C unit is most likely a 20A (it is in mine), with at least 12ga Romex wiring (rated for 20A continuous). Rule of thumb is to stay at 80% or less of a circuit's lowest-rated component, so the 16A of the larger 15k BTU unit is right on the money.

So, my analysis said that there was no problem with electricity supply, the units are physically interchangeable, use the same thermostatic control units, and the price difference is manageable (about $90). For this Texas boy that made the decision to purchase the larger one pretty easy.

It would be even more helpful if I had directly answered some of your questions.

In the case of the Dometic Brisk II 15k BTU Air Conditioner with a 16A pull - this represents a total of 44% of the output capacity of your generator. This is well within expected and safe capacity, even when coupled with other current draws like lighting and televisions. Pretty much no other concurrent draw is going to come even close to the draw of that A/C unit, so the remaining capacity in the generator should stand you in good stead. Again, the electricity demand of a 15k BTU unit vs. a 13.5k BTU unit is a very small amount of the total generator capacity.

My generator is also the Onan 4000, so for me the extra juice represents 1.9% additional load of the generator's total capacity.

Better to have and not need...

harleyjt · 05-13-2016, 04:58 PM

Size matters.

jt
2005 Newmar Kountry Star gas 3742, Workhorse 8.1L w/Allison 5 speed.

Sent from my iPhone using iRV2 - RV Forum

redcolorado · 05-14-2016, 07:24 AM

I just replaced my 13.5k rear heat pump with a 15k. My RV repair shop said the price of the 15k was $10 less than the 13.5K same brand (Coleman) and model and very little difference in current draw. Base on the current draw on my power panel the new rear 15k draws 1 amp less the my old front 13.5k. The total cost of him ordering the unit and installing it was $150 less than it would cost me for the unit.
Check the cost on line then check with a RV repair shop (not a Dealer). I was surprised how much less his cost was verses mine.