Portable A/C Unit?

[TowDawg]

I use my coach for 99% racetrack duty only, which means I'm generally parked in the middle of big parking lot with no shade, which in the south can get pretty dang hot.
I've got a 2002 Scepter with 2 roof units and they both blow cold and run all day, but the main living area gets above 80 on hot days because the combination of sun, outside temps, only 1 A/C trying to keep up in the main living area, and (I assume) pretty crappy levels of insulation.
I was contemplating adding a 3rd AC unit in place of the fantastic vent fan in the kitchen, but it sounds like a dual hose portable A/C unit might do the trick and be a heck of lot easier for those summer months to help keep the coach cool.
Does anyone have personal experience with using one?
I'm not worried about making a panel to route the hoses, draining the water if I have to etc. I'm more interested in what people might have used AND if you've had any issues tripping internal breakers with it running. I'm assuming I'm good with overall draw with all 3 (2 roof and 1 portable) running when using the generator or plugged into 50A shore power in terms of not tripping the generator or shore power breaker, but what about the internal breakers for the outlet I'd be plugged into? My plan is to put it by the kitchen table and route it out of that window, so I'd be plugged into the receptacle that's essentially above the kitchen table. I haven't looked, but I'm assuming it's on a 15 or 20 amp internal breaker.

[vito.a]

Are your A/C units original?
You might also think about upgrading the front A/C to one of the new Dometic 15,000 BTU Blizzard NXT units. They are redesigned for greater output and efficiency.
I upgraded our front A/C to a 15k unit a couple of years ago and the output temperature and volume are noticeably better.

[jacwjames]

I'd suggest checking what other outlets are on the breaker and not plug in any other loads while the portable AC is on. Also see if it is on the inverter or not as you may have a problem with it overloading the inverter itself if other inverted loads are used.
All of my breakers are 20 amp and my wiring is 12awg wire. If yours is the same you shouldn't have a problem.





I just upgraded my 2 AC units from 13.5BTU units to 15BTU units for the very reason. Last summer up in ND it was 100F and the two units would not keep up.

But one thing I'd suggest you do is get a inspection camera and check your duct work. I did before I installed my new AC units and glad I did, I found a large mouse hole in one side of the duct and a couple smaller ones. But also found one of the joints connecting two pieces of duct work not sealed, not tape at all. When I pushed the camera past it I thought what the heck but checked several times and confirmed. Only way to fix it was to install a new duct location at the seam so I could access and seal/tape the seam. Not telling how much loss cooling capacity I had with all the holes/leaks.



After the change I took a trip out west and temps got to ~90F and one AC was easily able to keep up. I'd rather have too much cooling capacity then not enough. Now I can turn the bedroom AC unit on and push the air to the front and at night the opposite.

[TowDawg]

I honestly don’t know if they’re original or not, but they do blow plenty cold.
I just don’t want to deal with potentially having to change the thermostat and all the wiring that goes with it if the new one isn’t plug-n-play with what’s already hooked up to the unit now.
As far as ductwork, it might have some issues, but I’ve got the “direct vent” option and even with that open, they can’t come close to keeping up.

[dizcom]

The thing about the portable A/C units is that none of them are very good. Consumer Reports did an article on them last month and wasn't very flattering. At best, they put out just a bit of cool, they're bulky and hard to work with, and they're noisy. I've tried a couple of them that I inherited from others over the years, and I agree. Your best bet is probably increasing the size of your installed units and doing something about the sun. Do you have a shade over the windshield? They get good reviews for keeping the cockpit area cooler. Magnashade is one of the more widely known brands, but there are others. Vent insulators also help keep the heat out and are widely available. Fans also help move the cool air around and keep you more comfortable.

[craigd853]

Originally Posted by TowDawg

I honestly don’t know if they’re original or not, but they do blow plenty cold.
I just don’t want to deal with potentially having to change the thermostat and all the wiring that goes with it if the new one isn’t plug-n-play with what’s already hooked up to the unit now.
As far as ductwork, it might have some issues, but I’ve got the “direct vent” option and even with that open, they can’t come close to keeping up.

Hello sir, do you have all of your blinds closed and keep the sunlight from entering the coach. As you said the poor insulation coupled with the fact that most motorhomes are like a convection oven in the summertime might help some. Any sunlight entering the coach during the day is going to cause heating problems. Also put a thermometer in the a/c and check the temp coming out of the a/c versus the outside temp. 21 degree difference and the system is working properly anything else drastically different you know you have issues. Good luck

[TowDawg]

Originally Posted by craigd853

Hello sir, do you have all of your blinds closed and keep the sunlight from entering the coach. As you said the poor insulation coupled with the fact that most motorhomes are like a convection oven in the summertime might help some. Any sunlight entering the coach during the day is going to cause heating problems. Also put a thermometer in the a/c and check the temp coming out of the a/c versus the outside temp. 21 degree difference and the system is working properly anything else drastically different you know you have issues. Good luck

All blinds (both in each window) are closed, as well as having the silver sun/heat reflector stuff in every window as well. I haven't tried the outside window covers, which are supposedly better than using anything inside, but I might try getting a set of the outside covers for the windshield. I've also thought about getting all of the windows tinted dark with the film that's also supposed to limit heat transfer. I'm sure both of those would help, but I think the insulation is just so crappy that it still won't keep cool with just the two roof A/C's.
As far as the units on there now, I haven't checked the air temp with a thermometer, but they blow very cold, so they seem to be working just fine. It's just too big of a space for 1 unit to keep the entire living area cool. (The bedroom stays pretty dang good since it's a smaller area with its own unit back there.)

[TowDawg]

Originally Posted by dizcom

The thing about the portable A/C units is that none of them are very good. Consumer Reports did an article on them last month and wasn't very flattering. At best, they put out just a bit of cool, they're bulky and hard to work with, and they're noisy. I've tried a couple of them that I inherited from others over the years, and I agree. Your best bet is probably increasing the size of your installed units and doing something about the sun. Do you have a shade over the windshield? They get good reviews for keeping the cockpit area cooler. Magnashade is one of the more widely known brands, but there are others. Vent insulators also help keep the heat out and are widely available. Fans also help move the cool air around and keep you more comfortable.

Thanks for the feedback on the portable units.
I'll look into the outside shade for the windshield, which I'm sure will help, but I think it's truly just a lack of insulation and too much space for the one unit in the living area to keep up.
I've used a fan to blow from the bedroom forward (bedroom will stay cool since it's a much smaller area with its own unit) and it does help, but the living area still gets into the low 80's on hot, sunny days while both units are running all day. (Where it really sucks is that some tracks only have old 30A service, so I can't run both units at full blast all day and have to fire the generator just to be able to keep them both going non-stop.)

[bigb56]

Living in the desert I feel your pain, there is a tremendous amount of solar gain through the windshield and the roof. I have considered one of these in the past and might be a consideration for you if you sit in one place for a while, keeping the roof shaded will drastically reduce the inside temperatures. The only real drawback that I can see besides the cost is two people to set it up each time.

https://www.facebook.com/savewithsha...9553554413967/

[jacwjames]

A 30 amp service is a big limitation as you usually can't run 2 AC units on a 30 am service.


The PO of my coach did a work around. The bedroom AC unit was hardwired in, there was a Jbox mounted to the side of the opening. He undid the wires, installed an outlet in the Jbox and a male plug on the end of the wire going to the AC unit. He could then unplug the AC unit and run an extension cord into the rear bedroom window, even had a small slip installed in the ceiling to neatly hold the extension cord.

When plugged into 30 amp he could run the front AC without worrying about shedding and then plug the rear AC into a separate outlet, which is the normal setup with a 30 amp service.

When I installed new AC's I keep it this way and even did the front that way.



One thing you can look at is the front cap above your windshield. I had mine apart while I was installing a new flat screen and found that there was no insulation behind he cabinets. I took a piece of batt insulation I had and worked it in. I've actually seen where others took the time to use spray foam, which would be better.



There is minimal insulation in these rigs and the sun beating down does not help. Early last year I took the time to clean my room and then paint it with the Rustoleum Topside white paint. It made a noticeable difference in the heat build in the ceiling.

[SteveJ.]

We had a problem with the front living area being too warm on hot days. The bathroom in the rear was quite cool. This in a '98 Safari Trek just short of 26' long. We have a fresh 13.5000 btu Atwood A/C unit, ducted.

Our answer was one of these:

https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

Very quiet, even on high. Smooth, doesn't take up much room and only draws about 50-60 watts on high, 120 volt. This fan evens out the temps quite nicely. We bought the fan last Sept. It seems to run fine on a MSW inverter when we only want the fan running when dry camping(90+% of the time)but we usually run it on our PSW.

As far as cooling temperature goes the cool air should be about 20* cooler than the interior air being sucked in, not the outdoor temperature. If it's much more than 20* you may have dirt or scuzz restricting the air flow at the evaporator(cooling) coil. Good for humidity control, not so good for cooling or for the A/C unit.

HTH and good luck.

[YC1]

When we were unable to get a replacement AC for the front during the pandemic I bought a portable unit.

To place it where I needed to required a bit or rewiring to get it onto a non inverted circuit.

Routing the air out the end of the slide worked fine and didn't look to pitiful.

The thing ran non-stop and was noisy sitting next to our chairs but it was desperate measures having to stay in Central Fl. Not enough shade where we were at for sure so that didn't help.

I did not resort to putting the bubble insulation in the windows but parking in open spaces for a race I would not hessitate to do that.

The front windshield must be covered from the outside. Covering it from the inside is a waste in this intense sun situation. We don't have a full blackout of the front. The material can be seen through from the inside but not the outside during the day. In the evenings the shades are drawn because you can see inside through it at night.

If I was to either add an ac or use a portable, I would definitely add a third one. More noise of course but you can just spend some more money for the silencers. They help a lot.

If for example you have the Dometic Penguins and wanted to add a third to the existing two, yes you would have to change a board to make the new one backwards compatible with the existing thermostat and units.

Repairing ductwork is really important. Ours had many issues even though brand new at the time. Registers stuck into the ductwork were not trimmed to the ceiling thickness so air had a difficult time getting up and over then down through.

After trimming those and fixing the area where the air goes into the ductwork there was a massive improvement.

[96 Wideglide]

Originally Posted by dizcom

The thing about the portable A/C units is that none of them are very good. Consumer Reports did an article on them last month and wasn't very flattering. At best, they put out just a bit of cool, they're bulky and hard to work with, and they're noisy.

That's what happens when you bring the condenser inside the room your trying to cool. Apparently, the models with two hoses are slightly better, but, you still have a little oven sitting in your room.

[vito.a]

Originally Posted by TowDawg

I honestly don’t know if they’re original or not, but they do blow plenty cold.
I just don’t want to deal with potentially having to change the thermostat and all the wiring that goes with it if the new one isn’t plug-n-play with what’s already hooked up to the unit now.

You will not need to change the wiring, but you will need to change the thermostat to match the new A/C. The various Dometic A/C generations both old and new use RJ11 telephone com cables.