Coleman Roof Top AC Units

[Jim Blackwood]

I get all that, and I'd guess you are just about at the limit of what that 50A service can do. But let's take an example or two based on typical wart construction.

Usually there is a common motor for both sides with a tin wall between them, at least in the older units and probably most of the newer ones too. Why? Because it costs less to keep making them that way. There is no reason why a separate modern efficient fan could not be used on each side except the cost of the redesign. There is no reason why a well insulated barrier wall could not be placed between the condenser and the evaporator. There is no reason why a modern and highly efficient compressor could not be used, in fact this is the one big contributor to the higher seer ratings. Why do they keep insisting on using less efficient compressors? Same reasons they don't redesign the unit as a whole. The volume of sales and the profit potential does not justify the redesign expense to the bean counters. And until someone takes a chance that the more efficient units will sell better it won't.

Jim

[luvrbus]

Carrier made a roof top with 1 motor((so did others) and used the condensation to cool the coil,I just took one off because of finding the parts was a problem since Carrier dropped the line.

Van has 13500 btu the blower motor stopped and I ordered a motor going from 1/4 to 1/3 hp to make a 15,000 btu unit roof tops are so simple

I am total electric and don't seem to have a problem but all 3 units never run when it cools inside ,I have ducted roof tops and the insulation seems good I know I have 6 inches in the roof so most of the time only one unit is running 2 at the most lol If I get the programing right one will keep it cool

[windtrader]

Jim hit on the primary reason RV rooftop AC are not more efficient - simply not enough demand from consumers. However, that may change if the boondock/off gird requirement grows enough to have this up on the must have checklist for RV shoppers.
There would be redesigned efficient rooftops today if the demand was there as the technology is well proven and actually not that great an investment in producing newly designed high efficiency units. The costs would be in the retooling and production side. That said, it would not be highly expensive but still doesn't pencil out ROI for makers since the demand volume is not there for the new over the existing, coming back to consumers not pushing for this capabiity.
To provide some perspective think about how many have converted to mini-splits DIY? Look hard because it is likely a rounding error, less than one percent. How many new RV have mini-split over rooftops, probably same share. Nothing is going to change.
 

[luvrbus]

Jim hit on the primary reason RV rooftop AC are not more efficient - simply not enough demand from consumers. However, that may change if the boondock/off gird requirement grows enough to have this up on the must have checklist for RV shoppers.
There would be redesigned efficient rooftops today if the demand was there as the technology is well proven and actually not that great an investment in producing newly designed high efficiency units. The costs would be in the retooling and production side. That said, it would not be highly expensive but still doesn't pencil out ROI for makers since the demand volume is not there for the new over the existing, coming back to consumers not pushing for this capabiity.
To provide some perspective think about how many have converted to mini-splits DIY? Look hard because it is likely a rounding error, less than one percent. How many new RV have mini-split over rooftops, probably same share. Nothing is going to change.

[luvrbus]

That may would change if the mini splits were ever redesigned for mobile use right now it is just for the DYI group,I doubt you will see mini splits 40 years old still in use though. The seer rating is a location thing,I just had a new unit installed last year here,the installer told me even if it says 20 seers expect around 10 seer in this heat,in Flagstaff he said the seer rating would be 20,the average for Phoenix is 14 seers is the best they can figure based on how many days you need AC and the temperature,we use AC here 9 months out of the year

[chessie4905]

Jim, super efficient air conditioners don't matter to me. I stay at campgrounds or limited boondock with generator. Not going to fool with solar, inverter chargers or lithium  ion, nickel metal hydride or whatever. Too old to get into it, with limited payback. BTW, I live in NE. 90 or a little more is about it around here in summer. Been out west two years ago. Too hot out there.
Thought about solar on shop roof-75 to 90k and payback after I'm  dead, but what really killed it for me was paying tax on income from it

[luvrbus]

Jim, super efficient air conditioners don't matter to me. I stay at campgrounds or limited boondock with generator. Not going to fool with solar, inverter chargers or lithium  ion, nickel metal hydride or whatever. Too old to get into it, with limited payback. BTW, I live in NE. 90 or a little more is about it around here in summer. Been out west two years ago. Too hot out there.
Thought about solar on shop roof-75 to 90k and payback after I'm dead, but what really killed it for me was paying tax on income from it

I am with you John plug end and unplug for everything else there is Onan cost me 3 to 4 bucks a hour to use under full load.No way you can recoup all the solar,20k in batteries plus inverters then you need a generator for backup.It is hot here but 3 hours we can be in the 70 degree mountains.The best investment to me in a bus is 30,000 btu dash air

[Tedsoldbus]

It is an interesting idea Jim, but I think the Amish at JC Refrigeration are swamped with just the refer business. They still do absorption but now need to meet the demand of the many residential set ups, tying into the solar rage with sometimes in adequate battery poser to run a residential set up swap out. I talked to them recently trying to help a BGM guy, and they are booked...forever ish since the new refers are about as good as the new A/C units.

Walked the dog over the hill today and my neighbor is building a house on the lake. They come from an hour away on weekends to check the progress and stay in their 8 month old 5th wheel. This is a picture of the mobile RV techs using a slick little winch to get the new A/C unit on the roof. They are replacing the rear A/C today since they replaced the front one a month ago. He said they are sealed units. Can't add any freon to it even though the test says it is low. He said the good news is it is still under warranty. Bad news is the new ones are the same thing and they are crap.

I head for Nappanee where we met Jim, end of September for meet number two. I hope you are coming. Rita still can't come this year so my sofa is still open for you if you want it again. I can promise  both of my 43 year old Duo Therms still work on hot and cold. If one of them dies, I will look for a newer one. Maybe a 38 year old Air Conditioner. I think before I'd buy a new unit I will just go back to what we did on hot days when I was a kid. Run with the windows down.

I hope you are making good progress on your bus. I'd love to see you get it on the road. Life is not a rehearsal.
Best regards Jim,
Ted

[luvrbus]

Even the fridges are sealed to, but all you do is add a $5.00 tap and valve and recharge the units,they sell a lot of AC units and fridges telling people they cannot be charged or find a leak

[Jim Blackwood]

Sept 21st to the 24th, it's a possibility but may be hard to do this year due to residuals from the attack of the giant bloody man eating spider that stabbed me 4 times in the gut. They say my convalescence ends in a week but recovery continues for some time afterwards as we all know and with the other things I have to do, appointments and such, well I'll just have to see. I will run up if I can but it may just be for a day or two again. The bus is coming along but I lost pretty much a whole season of prime working time so it won't be ready this year. If I do make it, maybe we can find a chance to run over to JC and speak with them about it. See if they are considering expanding the business.

I can see location playing a part in the seer rating I suppose, of course if you could find a way to park it in the shade that would make a major difference. Probably enough to justify some sort of a portable shelter for longer stops in some cases. I don't know how they actually do the testing that determines the numbers and without that it's just guesswork. But all else being equal the seer rating gives a very valid basis for comparison. In other words, if comparing a seer of 9 to one of 36, a reduction of 50% has you comparing 18 to 4.5 and it's still a four to one ratio.The higher seer unit will always outperform the lower one with less current demand. So there's that anyway.

But like I said, if it ain't broke don't fix it. If your setup lets you do all you want, is reliable and affordable, why spend money just because someone says something else is better? It may be perfectly true, but is it better for you? That's the real question. I'm all about getting the most out of your money.

Jim

[luvrbus]

There is no argument about inverter type compressor using less power than a standard compressor,they blow cold air for while the then air temperature will increase as they go along,you can take a iR gun and see that for yourself that is why the run longer because of reduced capacity but it takes less power to run longer,I hang with Coleman because  they are made in the US and 80% of the components are  made here.I don't do good with the Chinese made $#!%