Air8 Performance in T@B 400 & Resolution (Coming Soon!)

Denny16

Another way to reduce the trailer tongue weight caused by the CoolCat ACis to add additional weight behind the axle.  On our TaB400 (late 2018) the 12VDC 200AH, glass mat battery, which is around 120 lbs, is mounted back under the bed next to the driver side divider, front t back, adding a nice counterweight, resulting is around a 400lbs tongue weight.

While the Air 8 looks good on paper, it seems to be inadequate on the TaB 400, and going to the next larger 8-10K Truma unit seems like the best result, if the CoolCat is not an option, due to its size and weight.  The larger Truma unit is also a heat pump, and seems like a better replacement option for the CoolCat,,especially for trailers being used in hot climates, like Texas, Central Calif, and most of the South Eastern US.
Cheers

cottonmouth

I had a 2020 on order to be delivered late February. After a few calls with nuCamp and expressing my concern with Air8, nuCamp called me today to ask if I would be interested in switching my 2020 order for a 2021. I said yes contingent on what the a/c fix is. He could/would only tell me that they are working on 2021 prototypes and the new units should be built in the next few weeks. He said he would let me know as soon as he had more info on the specs. So I'm tentatively on order for a 2021.

TNOutback

Sounds consistent with what I’ve been told. Glad to see a resolution is coming and they are committed to it. 

JCALD

Be sure they tell you the BTU rating so you can see if it is close to the Cool Cat.

Redfish24

WOW,  I am now befuddled about picking up the 2020 that we had picked out.   Makes me want to wait on a 2021 fix now.  

I was getting a pretty good deal on that 2020 on the lot with all the colors and options we liked...  now, I am told from a 2nd dealer closer to my location that he can order me the 2021 but it will costs me $1000 more than the 2020 deal i was getting but some colors have changed a bit.    decisions decisions. 

cottonmouth

Just heard my 2021 is coming off the line the first week in March. The only change for me was they no longer offer the blue or vermilion cushions. They come in graphite only now. They still weren't able to tell me what the a/c is, so I'm still tentatively confirmed.

BirdieJane

New interior color image 
 

TabberJohn

If the Air8 is indeed based on the Saphir Compact, I don't see how it can possibly be rated at 8000 btu.
I think @rh5555 's chart is a likely explanation why it doesn't measure up.

As @Denny16 mentions "on paper" things looked reasonable and the Air8 was supposed to be just that -- an 8(000) btu AC small enough to fit under the bed and powerful enough to cool a camper of XX sq.ft.
Good intentions aside what they got instead was an Air6(000) with questionable thermostat control, coupled with air flow problems and a warmer cabin than a 320. So things went downhill from there.

As far as 10 complaints out of hundreds manufactured to date, that may be wishful thinking.
The only useful stats would require testing a group of 400s off the factory floor under the same conditions. 
For example, send several to a Texas dealer in the middle of summer and run a series of tests in an unshaded lot. 

Most RVs have roof mounted ACs with btu ratings far exceeding what applies for same size sq.ft. in a home. The reasons include massively different insulation properties and sun exposure.
 
I don't doubt nuCamp's sincerity and willingness to make things right, but I don't think the current Air8 performance and configuration will ever make everyone happy based on where, when, and how they intend to camp.
If your camping experience primarily consists of mountain visits in full or partial shade you may never experience the issue. On the other hand if you'll spend time baking in the sun where it's hot day and night...that's an entirely different story.

It appears a re-engineered Air8 under development should be the solution. As long as 8000 btu is achieved that may be enough, but I think they should consider reconfiguring the vents, airflow, and thermostat control to cover all the bases.

TNOutback

@TabberJohn agreed. I had suggested to Nucamp they consider moving the front a/c duct outlet from under the couch to up high next to the roofline where the upper cubby cabinet is. Would lose a small area of shelf, but for the same volume of air, it would be much more effective if it were up high instead of low next to the floor. 

rh5555

In my correspondence with NuCamp (in which I passed along my "physics lesson" from page 6 of this forum), this is the message I got back:

"Thank you for the information you have submitted.  I did pass this along to the appropriate people.  I know there was a fan added in the A/C area to help along with a different face plate that has more slots for air circulation.  Elwell is in the process of getting us a thermocouple harness that we will be able to send out to customers.  This will allow us to move the thermocouple inside the cabin to give the A/C a proper temperature reading. Elwell is also working on another A/C.​

When I have more information on the harness or the A/C I can let you know."

It looks like a better [sic] thermocouple harness (it is a thermistor, not a thermocouple) should be on its way soon.

gulfarea

A split system like the small ones they use in Japan would work great. The compressor mounted on the tong and the small air handler inside the 400 linked by the 2 copper lines. Art

Arizonayeti

I've already had my Air8 replaced under warranty last summer (previous post).  The new unit is no different than the original installed spring 2019.  The other day, I visited the trailer in the storage area and turned on the Air8 a/c function.  I was on 15amp service with the interior temperature about 74, outside it wasn't much warmer.  I set the temp as low as it can go...maybe 64f? and waited.  The a/c ran for about 15min then shut off.  There was no error code and the interior panel displayed 68.  I really have my reservations about this unit. As Arizona warms up the next month or two, I am going to test it several more times.  My tolerance is pretty low having a subpar a/c unit in a 30k trailer.  I don't summer camp in the desert, but I do head up to 7000ft and if I have full hookups, there are many afternoons where it is very nice to take refuge from the sun and heat.  I hope NuCamp finds some kind of answer for us 2020 400 owners. 

rh5555

This short-cycling of the AIR8 is because it measures the cabin temperature at the intake to the unit.  Cold air sinks, so you end up with 64F air at the floor, which is drawn into the AIR8, which thinks the cabin is cold enough, and thus shut down.  One of the promised enhancements is to have the temperature sensing done remotely.  This should address this particular problem.

Arizonayeti

@rh5555 That is right. Thank you for the reminding me that the temp intake is not at the wall unit. A remote temp sensor may help short cycling, but not sure it will help keep the 400 cool in hot weather.  Fingers crossed for the correct fix. 

RCB

Is there a heating/cooling engineer out there ? Notwithstanding its installation, location of sensors etc, has the unit been sized appropriately?  A heat loss/gain calculation would give a clearer indication of the required size for an a/c unit. Granted the ambient temperatures for the calculation would have to be suitable for those in hotter areas of the continent. Such a calculation would tell how many BTUs of cooling are required to maintain the desired temperature with the selected outside temperature. Until we know the unit is adequate from a design point of view, there is no point debating the merits of its installation. If I’ve missed it, I apologize, but I have not seen such info.

TNOutback

@RCB, the non-scientific answer seems to lie between satisfied 400/Cool Cat owners and unsatisfied 400/Air8 owners, or in other words, somewhere between 10,500 btu and 6,000 btu.  

RCB

TN, and if those units run at 90% efficiency, then the numbers are 9,450 btu and 5,400 btu. That is huge spread, that indicates the Air 8 is nearly 1/2 the size of the Cool Cat. There is no doubt in my mind the heat loss/gain calculation is the place to start.

rh5555

The ecomfort.com website has a calculator for sizing "mini-split" air conditioners for a room.  It offers quite a few adjustments, although none specific to trailers.  I fed in a room of TAB 400 size, with the big dinette window facing north (so our solar panels face south!), an outside temperature of 108F and an indoor temperature of 80F.  I then ran the calculation for their settings of no wall insulation and single pane windows (as a worst case scenario) and with fair wall insulation and double pane windows (as a best case scenario).

I then averaged these 2 results to generate the "TAB insulation" column, which is my guess of what our situation might be.  Had the AIR8 unit actually produced 8000 BTU/hr of cooling, it looks like it might have been appropriately sized.

Interesting note:  Most of the heat infiltration is through the roof of the trailer.  We need some cunning mods to address this...

Interesting note 2: 30% of the work being done by the air conditioner is moisture removal.  If you have "dry heat", you can remove this requirement.

Denny16

The TaB roof is aluminum, so we have a “Cat on a Hot Tin” roof situation.  The roof has closed foam insulation between the ceiling frames, and a non conducive headliner.  So the only other option I see is to add a “tropical” roof over the existing roof, a reflective panel with an air gap under it to shade the roof and allow air flow between the two surfaces, creates a cooling effect.  Land Rover did this on their tropical area Defender jeeps.  

A more practical solution may be just setup a shade awning over the roof when it is in the sun, otherwise, seek out a shady spot to park the TaB.
cheers

RCB

I think I saw a pic of an Air 8 ID plate that showed 6000 btu. Which is it, 6000 or 8000 ?

rh5555

Both 6000 and 8000 have been claimed, depending on when the trailer was manufactured.  Initially it was 8000, then subsequently dropped to 6000.  No apparent difference in the units.

Dutch061

Okay, you are going to make me think to hard on a Monday but here goes.

If I remember correctly from a few years ago when I had a 5th Wheel with a 13,500 Coleman Polar Mach Unit and I was talking with Coleman about adding a second unit, this is what I was told. a 13,500 BTU Unit can produce a Delta of 17 degrees and a 15K can produce a Delta of 20 degrees. Delta being the difference between inlet and outlet air temperature. The Coleman website shows a Delta of 16 to 22 degrees being normal, so my memory is likely pretty close to correct. I can say that using a digital temperature gun that the outlet temperature at the ducts was mid 60's with an inside camper ambient of close to 87 degrees when I started. This is a Delta of just over 20 degrees which seems to be what I would expect for this also. Of course the theory is that as the inlet air gets cooler the outlet air will get cooler too, which I observed as the inside temperature dropped.

We have a 2020 400 BDL we picked up 2 weeks ago that we had out over the weekend (first trip) in a remote area. It was uppers 80's outside so I fired up my generator to run the air conditioner. According to the digital display on the generator, the air conditioner was using around 1200 watts. "The Google" shows that an 8K BTU air conditioner draws 650 watts while running. The air conditioner was able to bring the temperature down to low 70's within a couple of hours. We were in full sun, so the thermal load was maxed out for a day in the mountains of NC. Granted, all of this is far from "scientific evidence" and I plan on keeping watch as the summer goes too.

My biggest concern is related to the location of the ambient air temp sensor being in the return air ducting or housing of the air conditioning unit. I can envision a scenario if you were to set the "desired temperature" to 72 that will be far warmer in there than that if you were to measure it near the thermostat. In fact I monitored it and the Air8 thermostat display was typically 10 degrees cooler (or more) than the actual or in comparison to the Alde Thermostat.  I set the thermostat to 62 when I turned it on and all was good.

Previously we had a 2017 TAB 320, and I can assure you that the air conditioner in that was not near as efficient or as cold as this has shown to be so far. In fact, in a similar situation it would not have cooled down until the sun went down.

Regards,

Brad

Denny16

Good test.  I think the Air8 is getting a bad rap due to the poor location of the thermo coupler on the thermostat and operator error.  Also expectations on what an AC should do is also a factor, along with thinking you set the thermostat to 68 degrees and expecting the trailer to get to 68 when it is 85-90 outside, and you start with a 90+ inside temp.
cheers

jkjenn

In 90+ degree weather, my window style AC on my 320 cannot keep up if in full sun. I hit a patch of of 100+ degree temps in partial shade and by 10:00 AM, the T@b started loosing the fight. As soon as the sun would go down, the trailer would cool off very quickly. 

@Denny16 is right on about a sunshade over the top. At one point, I had floated the idea of something that went through the order rails on both sides and raise above the roof (I can see it in my mind.) Maybe an inflatible structure.

splatmatt

@jkjenn I agree, however, I did find on our old 320 that moving the damper too far to the cold setting over extends and may cause more uncooled outside air to mix with the cooled air.

To all:
I feel that the insulation on the T@Bs is at best an R-value less than 10.  Typical 1/2' foam is only a 3 and and the Azdel on adds an R-val of ~2 per panel from my reading. Some say Azdel offers 3x of wood but depending on thickness that is any where from R-values 0.5 to 1.5.  I feel the t expecting a 6k or 8k BTU air cond. unit is underpowered for the T@B 400s volume.  One of the reasons why we switched to another trailer brand when we wanted a bigger trailer.  

From my experience, insulation requires thickness and trapped air; many trailers just don't offer that.  Then there are some that use fiberglass which is just asking for mold problems in trailer applications.  Our new 20' trailer uses a relatively thick ecobatt insulation that resists mold issues and provides a modest amount of trapped air, but it still uses a 13.5k BTU air conditioning. unit.

To sum, if the 400 is going to adequately cool interiors with it's given construction it simply needs more BTUs and properly placed sensors centrally located away from the direct flow of the cooling vents. 

Denny16

The R values of foam, depends on the foam, a 1/2-inch closed celll tech foam has an R-value of 5.  You would need to know the type of foam nuCamp used to be accurate.  But overall, the trailer has less insulation than a small house.  However, the TaBs are fairly tight air wise, so can trap air inside.
cheers

splatmatt

Denny16 said:

The R values of foam, depends on the foam, a 1/2-inch closed celll tech foam has an R-value of 5.  You would need to know the type of foam nuCamp used to be accurate.  But overall, the trailer has less insulation than a small house.  However, the TaBs are fairly tight air wise, so can trap air inside.
cheers

That is why I said less than 10 for r-value. ~5 for foam + ~2 per azdel panel.

Trapped air in the living space doesn't help; a trapped air barrier is needed to shield the living space.

simonseyz

Gents, when I replaced the fan in my 2018 400, I was able to see the insulation in the roof and it was not foam. It was some type of white fiber batt insulation. Now maybe that's what they used just around the fan.....but I don't think so!

Denny16

I have seen videos of nuCamp bui,ding the TaB 400, they use foam between the aluminum frame stock on the roof.  The sides are solid foam bonded to the Outside and inside panels.
cheers

splatmatt

My point regarding insulation was simply: regardless of insulation type there isn’t enough insulation for a small Air Cond unit to work effectively in the 400. You don’t need an engineer as any HVAC installer could tell you this. Ideally you want an air cond unit to be powerful to enough to effectively cool and dry air but you also do not want it so powerful that it only runs for a very short interval.  A short interval run will not have enough time to effectively circulate and dry cabin air. I imagine around 11k BTU unit would work for the higher temps that overwhelm the models’ insulation efficacy while delivering long enough run intervals to remove moisture and cook the air.  13.5k unit may work too, but only a real world test will show if it’s run cycle will be too short. The supposed 8k and 6k units even with a properly placed sensor would run for long intervals but not have the ability to effectively cool and dry the cabin air in common higher summer temps as the insulation just isn’t enough. Kind of like the difference between a Yeti 3” walled cooler and a cheap grocery store cooler with barely a 1” wall; the ice in the cooler with the thicker insulation will last longer and yield cooler temps than the in the cooler with thinner (less) insulation. Both coolers having the same interior storage volume and amount of ice. So either the 400 needs a better insulation factor or more fresh ice added frequently.  (BTUs).