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

TabberJohn

TNOutback said:

The Air8 thermostat is reading 70.7 degrees while the other two independent thermometers are 79/80. 

Is there is any way to calibrate the Air8 thermostat to match your independent thermometers?

VictoriaP

@TNOutback Please make sure to communicate your findings to both the dealer and directly to nuCamp. If this is within the realm of normal and expected behavior, it’s grossly inadequate for most places in the US in summer, and nuCamp needs to resolve this for everyone. If it’s abnormal, they need to know so they can fix your unit.

TNOutback

TabberJohn said:

TNOutback said:

The Air8 thermostat is reading 70.7 degrees while the other two independent thermometers are 79/80. 

Is there is any way to calibrate the Ai8 thermostat to match your independent thermometers?

If there is, I cannot find it. The manual is quite sparse. (The Alde, on the other hand, does have a temperature offset function.)

TNOutback

Final high temp for the day in the camper was 82, with an outside high temperature of 85.

I love everything about this camper . . . Except the air conditioner. :(

Cbusguy

The air8 manual is horrible.   It is only 4 pages with only the base stats and a rough explaination of the panel graphics.

Nothing else.

Design team......pffft, I envision a few of the builders sitting around a table at lunch drawing on napkins.     

That is the reason my door leaks Everytime it rains , my solar panel only delivers half of what it should and my trailers AC won't cool it down.

There is no testing department.....we, the consumer are the testing department.

jkjenn

Let's try to keep he conversation constructive. 

ChrisFix

TNOutback said:

Final high temp for the day in the camper was 82, with an outside high temperature of 85.

I love everything about this camper . . . Except the air conditioner. :(

I have doubts about the Air8 capacity even if running perfectly, but your results seem to be getting worse with each test...and makes me think your unit in particular isn't operating at its rated performance. 85 outside / 82 inside sounds like an air conditioner that is low on refrigerant. 

TNOutback

ChrisFix said:

TNOutback said:

Final high temp for the day in the camper was 82, with an outside high temperature of 85.

I love everything about this camper . . . Except the air conditioner. :(

I have doubts about the Air8 capacity even if running perfectly, but your results seem to be getting worse with each test...and makes me think your unit in particular isn't operating at its rated performance. 85 outside / 82 inside sounds like an air conditioner that is low on refrigerant. 

Outlet temperature nearest the unit is between 60-61 degrees, so I think the temps are as expected. It wouldn’t be that cool if it was low on refrigerant.  It just doesn’t have the horsepower to overcome the heat gain.  Again, it only has 60% of the cooling capacity of the Cool Cat that it replaces.  Today was interesting in that I started with a cool camper, not trying to cool off a hot one, it was much lower humidity, and you are right, I would have expected it to do better today but ended up in about the same place, temperature-wise.

4ncar

I’m curious what other ‘20 400 owners are experiencing, and whether this is a one off or not. Not discounting your thorough testing, @TNOutback, just haven’t  seen others chiming in...

Sharon_is_SAM

@TNOutback, It just seems like the cool air is sitting on the bottom.  Try a portable fan that you can sit on the floor to direct the air up.  Can you turn on the Fantastic Fan on exhaust without opening the vent?  That may help mix some air, too.

Sharon_is_SAM

@TNOutback, would it help to close the vent with the 90 degree ductwork?  Would that force more air through the other ducts or do they all have 90 degree angles?

TNOutback

Sharon_is_SAM said:

@TNOutback, would it help to close the vent with the 90 degree ductwork?  Would that force more air through the other ducts or do they all have 90 degree angles?

I don’t think there is much to be done about the sharp turns coming out of the unit.  It’s packed in that space pretty tight under the bed.  It just creates a little bit of a loss of blower efficiency with those turns in a unit already challenged.  Shutting off one won’t smooth out the airflow of the other two.

TNOutback

Sharon_is_SAM said:

@TNOutback, It just seems like the cool air is sitting on the bottom.  Try a portable fan that you can sit on the floor to direct the air up.  Can you turn on the Fantastic Fan on exhaust without opening the vent?  That may help mix some air, too.

Turning on the bathroom vent to exhaust absolutely helps cool off the bathroom, but I haven’t noticed the same impact with the fantastic vent fan.  However, you’ve given me the idea to put a thermometer on the floor, on the kitchen counter, and near the Air8 thermostat to gauge the stratification of the air.

VictoriaP

I agree with Sharon. Some sort of decent fan that could pull the cool air upwards and circulate it may help. I have less faith the stock Fantastic Fan will do much, I’ve had them in the past and found them so worthless that I had mine replaced with the MaxxFan before delivery of my 320.

At home, I use inherently inefficient, single hose portable ACs paired with 12” Vornado brand fans. On their own, both portables are also significantly underpowered for the spaces they’re expected to cool, and the house is a 70’s era split level with minimal insulation, cathedral ceilings, and lots of floor to ceiling windows that barely qualify as double pane (some single). Left to themselves, the ACs produce cold air that literally drops like a stone to floor level and goes nowhere. Paired with the Vornados and with drapes closed against any direct sun, both rooms can hold in the low 70’s when it’s 90°+ outside. Without AC *and* fans, those rooms will hit 85 or higher. 

While I still think it’s ridiculous that such an underpowered unit is being used on the 400, I’d definitely try putting a good room circulating fan in there as an experiment, close the shades against direct sun, and see if the readings change. 

TNOutback

Sharon_is_SAM said:

@TNOutback, It just seems like the cool air is sitting on the bottom.  Try a portable fan that you can sit on the floor to direct the air up.  Can you turn on the Fantastic Fan on exhaust without opening the vent?  That may help mix some air, too.

@Sharon_is_SAM my Fantastic Fan will not operate unless the vent is opened a couple of inches.

jkjenn

TNOutback said:

Sharon_is_SAM said:

@TNOutback, It just seems like the cool air is sitting on the bottom.  Try a portable fan that you can sit on the floor to direct the air up.  Can you turn on the Fantastic Fan on exhaust without opening the vent?  That may help mix some air, too.

@Sharon_is_SAM my Fantastic Fan will not operate unless the vent is opened a couple of inches.

It is usually recommended to open the vent a slight amount to help with air circulation, anyway. 

TNOutback

jkjenn said:

It is usually recommended to open the vent a slight amount to help with air circulation, anyway. 

Interesting.  The T@B 400 manual says to close all shades, close all windows and doors when operating the a/c.  I’ve tried opened, closed, and open and exhausting, and none seem to make any difference.

By the way, I put one thermometer on the floor and one next to the Air8 thermostat.  The floor reads 81 degrees this afternoon, while the one next to the Air8 thermostat reads 84 degrees.  The Air8 itself reads 72 degrees.  The air seems to mix well based on that spread.

Sharon_is_SAM

I think the recommendation to vent was related to using the window A/C in our small 320s.  It improved air circulation because you are pushing an excessive amount of air into a small space.  When not using the A/C, cracking the vent and a window prevents condensation.

TNOutback

Update:  I think I’ve stumbled onto something, but it leaves me confused.  Today was a carbon copy of yesterday weather-wise, except 2 degrees warmer: high of 87 and still relatively low humidity.  Yesterday I noted that the Air8 thermometer was reading as much as 13-14 degrees low compared to two other thermometers I had in the camper (that agreed with each other).  So today I set the Air8 thermostat as low as it will go: 61 degrees.  During the afternoon it still got up to 82 degrees in the camper, except today the camper recovered much more quickly after going into the shade.  I’m not sure when, but it had dropped to 68 degrees when I checked it at 6:30PM, which would be 3 hours out of the direct sun.  (Yesterday I had the thermostat set to 70, and it still was 78 degrees in the camper when I shut it off at 9PM and opened the windows.)

I do know I have a wildly inaccurate thermostat; that’s at least part of the issue I believe.  The rest ??????

BigShowSkipper

TNOutback, I recorded the performance of my unit under direct sun in 110 degrees at the hottest. My unit consistently cools the inside 20 degrees less than outside air. With shade it cools 25 degrees from outside. My dealer installed a baffle.  The thermostat seems like a likely candidate for some of your frustrations and hopefully improves performance once you make adjustments. 

TNOutback

@BigShowSkipper is your exterior color white or silver?  Is the thermometer on your Air8 thermostat very accurate?

BigShowSkipper

My color is silver and the thermostat is within 1 or 2 degrees. We use a couple plug in fans on the hottest days to circulate cool air

TNOutback

So I’ve completed another cooling test today.  This one I started with a hot camper at 5:00PM local time, The sun had been off the camper for 2 hours.  The 5:00PM readings are at the point of starting the a/c.  I set the Air 8 on max fan and set the thermostat to its minimum temperature, 61 degrees, then checked every hour.  Note the best temperature differential achieved is 8 degrees when I stopped the test.  The indoor temp crossed my “goal” temperature of 74 degrees sometime during the 4th hour.  Also note that the Air 8’s temperature readings are extremely inaccurate, but improve as the temperature declines inside.  To me, this test emulates towing your camper to a campground, during which time the interior will heat up, then seeing how long it takes to get the interior comfortable after arriving.  I’ll repeat this test when these crazy hot temperatures get more seasonal.  Still concerned about cooling capacity; it was 2 solid hours before I got a negative temperature differential to the outside air.

TabberJohn

5pm to 6pm is odd. Did you open the ceiling vent, all windows, and the door and run the ceiling fan on full blast before starting the test? 

How about replacing the thermostat? 
A wacky thermostat would definitely affect operation and performance testing.

Only comparable test I could find amongst the Air8 threads -- from a 400 owner -- is this one:
https://tab-rv.vanillacommunity.com/discussion/comment/120946#Comment_120946
@BigShowSkipper is getting a consistent 20 degree delta across the board.

It appears the Air8 is working fine for 320 owners, with or without the Service Bulletin fix. However, the 400 configuration is a lot different with fore/aft cabin sections to cool, awkward position of the AC under the bed, plus no frame rail separation of intake/exhaust vents underneath.
Perhaps what you need is the baffle fix @BigShowSkipper went with plus your thermostat replaced.

TNOutback

I agree, @TabberJohn:  a new thermostat and the diverter mod that @BigShowSkipper has shown us. Both may improve the performance. However, there is a key difference:  he’s in Arizona and I’m in Tennessee.  We have this thing called “humidity” over here to deal with.  That handicaps my air conditioner over his; it has to work harder to achieve its results, so one would expect an a/c in a dry air climate to work more efficiently than a wet air climate.  High humidity heat can double the cooling load compared to dry air heat.  At the end of the day, I still believe the a/c is undersized for the 400; you certainly cannot believe a 6,000 btu unit will perform the same as a 10,500 btu unit.

TNOutback

TabberJohn said:

5pm to 6pm is odd. Did you open the ceiling vent, all windows, and the door and run the ceiling fan on full blast before starting the test? 

No, I did not attempt to evacuate the air before starting the test.  I followed the manual’s recommendation to be sure all windows, doors, vents were closed before running the a/c.  I could give that a try, but I’m not sure how long or how effective it would be since the outside temp was still 93 degrees when I started. I was thinking the a/c would be more effective at dumping heat with everything closed up.

Cbusguy

On the truma website they show their other units having the ability to be calibrated through a service mode with +- 5 degrees of correction.    I emailed Elwel to ask if their version has that ability we will see.

rh5555

Reading through the AIR8 manual, I noticed 2 things:

• The "Norminal [sic] cooling capacity" is 8000BTU (not 6000BTU)
• The minimum opening for the air return is 50 sq. in.

I wonder if this air return opening is part of our problem.  We have 7 slots cut in the bulkhead between the air conditioner space and the rest of the trailer.  Each is 26" long and 7/32" wide.  This only adds up to 40 sq in.  Additionally, that area needs to be discounted because narrow slots present way more air resistance than one big hole.  Next, the area behind these slots is packed with pipes and cables which further hinders the air flow.  It seems we may be starved of return air, or worse still, outside air might be getting drawn in instead of trailer air.

I cannot do any significant test here (Pacific Northwest: 60F outside!), but you guys in Arizona and Tennessee can:  Try cooling the trailer with the access door under the bed propped wide open so that you won't be starved of air return.  See if this changes your ability to cool.  I would also be interested to know what happens to the humidity when running the AIR8 in TN.  It should drop and stay low, unless outside air is getting drawn in.  That could be another clue...

TNOutback

@rh5555 the manual with my unit and the label on the unit itself both say 6,000 btu. 

Ive wondered about that return air as well, just had not tried to measure it. 

Cbusguy

The thing to remember,   I says it is good for a 20 degree drop in temperature,  It is meeting that.    while we might not like it,    the device is functioning as expected.

I wonder if you got the wrong one installed in your unit @TNOutback.     it would make sense for them to install an 6k in the 320 and 8k in the 400.

need to look at mine when I get home.