A/C ductwork

Vonbrown

I have a 2018 T@G. Inside, there are 2 vents on both sides of the cabinet where the A/C unit is installed. What are they for? I have heat coming out of the vent on the right side. This makes no sense. The A/C fan switch is on. (I can hear it running)
Where does the hot exhaust exit from? Any illustrations of the ductwork construction? Perhaps bigger exhaust fans? I may have to remove the A/C unit to inspect this exhaust area. Something doesn't seem right. Any help?

Sharon_is_SAM

I actually just spoke with Creed from nuCamp about this subject. He said that the 2 side vents are to draw air into the A/C units via computer fans. He said sometimes the fans get installed backwards, so that may be the case with your one hot vent. As far as the exhaust, it exits under the camper along with the A/C condensate drain tube. The fresh air intake also comes from under the TaB which makes me wonder if that impacts the efficiency.

Vonbrown

I inspected the 12v fan installed under the ac unit and the air flow is in the correct direction.
I may modify this setup a bit with 2 bigger fans. I only have 1 dc fan installed. I blocked off the right vent until I get this figured out.

WilliamA

@Sharon_is_SAM said:
I actually just spoke with Creed from nuCamp about this subject. He said that the 2 side vents are to draw air into the A/C units via computer fans. He said sometimes the fans get installed backwards, so that may be the case with your one hot vent. As far as the exhaust, it exits under the camper along with the A/C condensate drain tube. The fresh air intake also comes from under the TaB which makes me wonder if that impacts the efficiency.

There are 3 fans in there, or at least were in my 2017 T@G. The third is accessed through the small wooden hatch under the A/C bumpout. One of my fans was also pointing the wrong way, although I can appreciate how easy that would be to do. I pulled my A/C so I turned both top fans so they draw air in through the "cowbell" ducts and distribute it into the cabin. I disconnected the bottom fan and removed it, then plugged the bottom inlet under the trailer by clever application of duct tape. Now I get a nice, gentle fresh air input constantly.

Also, putting a layer of double-sided rubber tape between the fans and wood housing makes them MUCH quieter.

WilliamA

Vonbrown

This setup needs to change. I can smell the hot wood in the air after the compressor cycles off. I'm gonna have to wait for cooler weather to figure this out. I'm in Quartzsite, Arizona for now and it is hot!
The A/C cools the trailer ( 75F inside 104 outside settings at high cool at 4.5 thermostat.
I just think if I can rid the exhaust better.........

Sharon_is_SAM

The TaBs A/C exhaust out the side of the trailer and we use a simple heating register deflector to separate the fresh intake air from the exhausted air. It would be hard to do that under the TaG!

Vonbrown

I have read a post where someone reversed the two upper fans to draw fresh air into the cowbell on the sides of the trailer and blocked off the fresh air intake under the trailer. I would like to increase the airflow out the exhaust, like install a fantastic fan in the exhaust plenum, or a 20" 120v box fan, well, you get the idea.

Sharon_is_SAM

@Vonbrown, see @WilliamA’s message above. Have you checked the airflow direction at the exterior cowbell vents? They should draw air in. Just thought of something else that may help. When you run the A/C, crack a side window. That may help pull in more air through those side vents.

WilliamA

@Sharon_is_SAM said:
@Vonbrown, see @WilliamA’s message above. Have you checked the airflow direction at the exterior cowbell vents? They should draw air in. Just thought of something else that may help. When you run the A/C, crack a side window. That may help pull in more air through those side vents.

I see a new thread coming here... The factory airflow at the cowbell should be out. Air enters through the bottom vent, captures heat from the A/C, then exhausts out the cowbell. I plugged the bottom inlet, disconnected the bottom fan and reversed the upper fans to draw air in and vent it into the cabin through the vents on the sides of the center cabinet. You must keep a window or the top vent open for that to work. The fans are small and won't have much airflow but will make a dramatic difference in humidity levels and temperature. Moving air around is deceptively difficult. It doesn't want to move very much. I like to think of it more as "coaxing" air around. The plenum in a T@G is a nightmare of square corners and impediments to good efficient airflow. Low volume air is all you can reasonably expect to get. But even low volume is very effective in keep in the cabin fresh and dry. To move a lot of air you will need a fan capable of pressuring the plenum like a squirrel cage fan. They are noisy and take a relatively enormous amount of energy to run. More later...
WilliamA

Sharon_is_SAM

So @WilliamA, are the inside vents on the sides of the A/C supposed to draw air out of the cabin into the A/C? The fans have been known to be reversed effecting air flow direction at this area.

Then the exterior vents should exhaust to the outside? Sorry if I confused those. I know Creed did not use the term cowbells, but that is indeed specific!

WilliamA

@Sharon_is_SAM said:
So @WilliamA, are the inside vents on the sides of the A/C supposed to draw air out of the cabin into the A/C? The fans have been known to be reversed effecting air flow direction at this area.

Then the exterior vents should exhaust to the outside? Sorry if I confused those. I know Creed did not use the term cowbells, but that is indeed specific!

Sharon,
I'm not privvy to inside information from NuCamp, but as I understand it, the airflow for all of this works thus:
The bottom vent in the trailer pulls in cool air. It circulates up and around the A/C unit, then the two top fans pull the heated air out and push it out of the cowbells. It takes advantage of the natural convection of heated air rising, rather than trying to force heated air down, where it doesn't want to go.
For those of us who removed the A/C units, reversing the two top fans (easy to do once you figure out how to get to them) will now pull air in through the cowbells, venting it into the cabin through the white grates on the side of the cabinet. For that to work, you of course need to have a window or the top vent open so the air in the cabin doesn't get "pressurized" which makes the work of the tiny fans nearly impossible. All you really need is a constant supply of low volume, low pressure air from the fans. It really is remarkable how much better the air quality and humidity is if you just replace the cabin air. The modified airflow system should be called an air exchanger. That's what it does; draws in fresh air and pushes the old air out the window or vent. It also, by the way, has the added bonus of keeping the air in the trapped plenum behind the wall from getting hot from the electronics back there shedding heat in with nowhere to go. You could leave the fans so that instead of pulling air in from the cowbells to drawing it out of the cabin through the vents and pushing it out the cowbells, but I personally like the idea of fresh air coming into the cabin from the vents. For "vortex of death" wind velocities, you'll just need to turn on the ceiling fan.
Not to make things even more complex, but I also use a small, house fan that I've put on the wall on the inside of the trailer to paddle air around. Unlike the plenum fans or roof fan both of which actually exchange cabin air, the wall mounted fan I have just stirs air around within the cabin.
The whole point of the exercise is to remove old air and draw in fresh air, taking with it the buildup of humidity that's inevitable whenever we breathe off water vapor.
This conversation is getting into the whole HVAC world of theory, but the point of the spear is, however you move the air by pushing or pulling, a gentle exchange of air will both cool and dehumidify within the bounds of what the temperature and humidity of the outside air actually is.
More later.
WilliamA

Michael

My 2018 does not flow like that. The two top fans flow inward into the plenum and the bottom fan blows downward out the bottom vent. I know because I put rubber grommets on the fan mounts to try to get rid of some of the vibration being amplified by the wood panels which did help some.

The bottom vent in the trailer pulls in cool air. It circulates up and around the A/C unit, then the two top fans pull the heated air out and push it out of the cowbells. It takes advantage of the natural convection of heated air rising, rather than trying to force heated air down, where it doesn't want to go.

Sharon_is_SAM

Thanks @WilliamA. Now I understand, 1 fan draws air from under and behind the A/C and then 2 side fans that exhaust hot air out the cowbells. So the vents inside the cabin on either side of the unit should allow air to enter around the A/C. So, still, if a fan is backward, hot, exhausted air will enter the cabin. Thanks.

Geoff_Acker

I'll add my two cents here. I can say with 99% certainty that the air flow is in fact designed to suck in through the side cowbells and exhaust through the vent on the bottom of the camper. Though it goes against the physics of hot air, which rises, i doubt nucamp would have exhausted the hot air up behind the cabinets. If this was how the system vented, hot air would be coming out right besides the windows. I'm also pretty sure, the hot air would leak through the removable back panels in the cabinets and leak back into the main cabin pretty bad. As it's designed, the system seems efficient though. In regards to the hot air coming out of the side vents on the AC cabinet, if the AC in on without the AC fans being on, you will have hot air coming out of those vents, if you turn the AC fan on, the hot air is sucked back through the vent shaft and out through the bottom. Hot air should not come out of the circular vents if both the AC and AC fan are on. What you may be feeling if you put your hand on the circular vent is residual heat from the AC which is right behind the vent. The AC cabinet feels warm to the touch regardless because the AC is exhausting hot air and wood absorbs heat pretty easily.

In regards to the access panel below the AC (where the lower fan is mounted), i also found this panel to get very hot as the bare wood just absorbs the heat going down the vent shaft. I covered the back of the panel with reflective, metallic duct tape and used silicone to seal the seam between the insulation cutout and the wood cutout, if that makes sense. This proved to reduce the heat absorption on the access panel.

Sharon_is_SAM

@Geoff_Acker, that makes perfect sense. Creed did say, one way to check the fan direction on the inside intake vents is to put a piece of tissue paper up against the vent. If it doesn’t stick, the fan is reversed. He also said that the A/C did indeed exhaust out the bottom, hence my first comment. OK, I will call nuCamp and make that 100% certain.

WilliamA

Well don't I feel embarrassed! (Okay, I really don't, but I think decorum demands that I say I am). If the factory design truly is to exit hot air out the bottom(?) then that goes a long way toward explaining why my A/C never worked well and why it's sitting on the floor in the shed with my collection of other things that seemed like a good idea, but weren't. For a graphic demonstration of that principle, try filling a balloon half full of air and submerging it in a swimming pool. It can, with enormous effort, be accomplished. Better to let it rise up where it naturally wants to go. My dad used to say that you can push a rope, but it's a long way in that direction to a finished job.
WilliamA

Lightningdon

I have my fans moving hot air up toward the cowbells. Heat rises, why fight it.

HellFish

Wow...this conversation is all over the place. If you turned the A/C on to say level 4 or so, on let's say an 85-90 degree day, and it got real dry and real cool inside the cabin, then we wouldn't be having this conversation. We don't talk much about the galley light 'cuz it works. We don't talk much about the axle 'cuz it works. However, for whatever reason, an A/C unit that should be able to freeze you out with dry air, doesn't. There is a problem with this cooling design, but (after drilling some drain holes in the bottom of the A/C) I have resigned myself to live with mine as is. Sigh...

LuckyJ

@HellFish , the galley light and the axle do have issues, it was talked about in other post! Lol

TennTim

Yeah, That galley light is bright! At least until I covered it with a dimming transparent vinyl sticker sheet.

Seriously though, I agree. This shouldn’t be a difficult thermodynamic problem given a unit that could cool a small bedroom struggling with small space.

I’ve always been skeptical of the vents on the sides of the cabinet that holds the unit. You don’t do anything like that if you have it hanging out your bedroom window by leaving a gap to the left or right. You seal that up. It should blow cold out the front and you need to get rid of the hot and condensate that comes out the back. The two zones should never meet. Whether air is sucked in or blown out those vents, it’s undoing the work of the unit. If you did that to the extreme, you would only heat up the cabin. Like opening the fridge doors in a sealed room and expecting the room to cool down. It will actually heat up since you’re putting energy in the room from that plug in the wall. Those three laws of thermodynamics get you every time!

If the issue is the stagnant air on the sides needing some flow to help remove heat, it would seem better accomplished by circulating the air already back there closer to the front instead of sucking cooled air across the zones.

Maybe one day I’ll take mine apart to truly understand what’s going on back there but I suspect it has to do with cramming an A/C unit designed to hang out a window in a small boxed in, poorly ventilated, space.

Having said all that, mine does perform well enough in the weather of the East TN region of the world. Just the chemical engineer in me doesn’t understand what’s trying to be accomplished or at least agree with the solution.

And yes, mine blows hot air out the bottom and sucks in on the cowbells and will only sometimes rarely drip condensate.

LuckyJ

Well, reading this last post, got me into thinking at how my portable hous AC seams to be working.

I could say that it is a portable window unit, that connect to the window by an air duck. And by that air duct, only hot air is blown out of my house space. Water drips in a pan in the AC that I would have to empty very often, if it was not for the hose connection in the back. With that hose connection, I will fill up to 2 5 gallons bucket a day of dripping water.

In order for the ac to performe well, I have to crack an other window open and I can tell you that a lot of air is pull through that open window. And it is a 3 1/2 room appartment, not a 30 sqft closed space.

So yep, I think those unit need those little side air vent that is providing air to cool the room area, it needs a crack window to circulate that air inside the ac unit and it needs air vent in order to circulate that warm air in the back. And when that fan switch is off, it make a very big difference. I remember that I knew that I did turn that switch off by accident, cause the wall was getting to hot to touch with my feet, so I would search for thw switch with my big tow, to turn that switch on again, and just a few minutes later, the wall would be confy again and the air would also be cooler coming out of the AC.

As for witch direction the air is going, I will have to verify this in the begining of next week.

As for now, my ac drain is dripping when the air is moist, condensation would even form on the outside wall of the trailer in the hot and humid morning of Orlando FL and it was supper confy to sleep with my nose frozen. With the sun up, the stargazer shade had to be closed, but it was still confy, but not as freezing.

Sharon_is_SAM

It has certainly been extremely humid where we have camped this year. Envious of those out west with their low humidity. It may also help to run your overhead fan to circulate air and draw air into the cabin from the cracked window. Keeps the air moving.

Geoff_Acker

I've tried different combinations of venting with my AC on. I had a temp/humidity monitor with me to measure the changes. With the windows/roof vent all closed, I set the AC on Low cool/setting 6(of 7). The manual says to only run high cool for a few minutes in very hot conditions and to use the low cool setting for long periods such as sleeping. With the AC on those settings I was able to achieve 70-73 degrees and low 70's RH. The problem is the output of the hot air in the back of the unit. When the AC condenser cycles off the AC just circulates unconditioned cabin air, and I think it may be pulling in some of the heat that is being vented out the back. You can certainly tell a difference when the condenser cycles off as the air coming out of the cooling vent feels humid. Then I tried opening the top vent and another time cracking the window to vent. Both times the RH rose to the upper 70's. Temp also went into the upper 70's which is a little too hot. It felt like the AC was just trying to compensate for the humid air being sucked in when the windows were cracked. My condensate seems to be draining correctly as there is always a stream of water in my drive coming from under the camper. So I think I'll keep the windows closed until October. I'm in NC so it's still humid as H### here. I think it all comes down to getting the hot air out of the camper efficiently and not letting it get sucked back in when the compressor cycles off. There is still some work to be done by Nucamp to make the TAG AC as efficient as it could be. Then again, maybe it is what it is. Nucamp was nice enough to put AC's in these campers and that's as good as its going to get. From what ive seen, most teardrops don't have AC. I'll take any type of AC vs. no AC any day of the week and twice on Sundays.

TennTim

@Geoff_Acker try a test putting tape over the round side vents on either side of the A/C. See how that affects your temperature and humidity vs. not covered. That’s how I would test my theory.

If some circulation is needed and couldn’t be fixed by mixing in the back, an adjustable opening vent might be the compromise needed. Again a test with varying levels of tape coverage could test that.

@LuckyJ if your unit only had one hose to the outside, then yes you would need to supply air coming in to allow the hot air to be blown out. A better way would be if your unit had two hoses to suck in outside air and blow out the heat. With only one hose it means the same problem I fear from those side vents. You’re sucking out your now cooled air and needing to suck in warm humid air to take its place since we can’t live in a vacuum. And humidity is what AC struggles with the most.

LuckyJ

@TennTim I have to confess that I have never given any tought to an AC unit before this topic came up, and I have never pull the unit from the T@G out of its actual location, witch would help understand how it work. But if it is pulling hot air from behind the panel, then it is trying to cool down very hot air.

But like I said, ours was giving us realy good result with top vent open in 80 ish degree 90% humidity weather and almost no humidity inside with the sealing vent open and one side window slithly open.

In 96 F still 90% bright sunny sky, with the stargazer shade closed, it was also confy. But we where keeping it in cold mod.

But I am not able to run any test for now, first, trailer is not at my location, and as we speak, it is about 53 outside as i write this. And was for about 3 days. Lol

nbrandt

I have just watched the Oregon Ducks lose a game that they should have never lost to Stanford.
Which in turn reminds me of this AC Unit in the T@G.
This is a window AC unit. In reality it should cool down that small space in a heart beat, however it seems to struggle. I don't think it has been intentionally hobbled, but it doesn't seem to run as efficiently as it should and no doubt, some of that is because it isn't hanging outside a window as it was originally intended. Therefore it needs venting attention.
I'm sorry, but I need definitive pictures and schematics as to which way fans should be blowing. Confidence is not built here by the factory admitting that it is possible that they have been aimed the wrong way - but just what is the right way? What's the logic here? I have to agree with WilliamA that there is no way that it should be trying to force hot air down through the bottom. That doesn't and isn't going to work. The cowbells - both of them - have to be exhaust vents - right?
The internal side vents on both sides of the AC are perplexing. Is this like a vehicle AC unit recycling internal air?
What is the role of the the roof vent and windows? What is the recommendation?
Being in Oregon I have to admit that I haven't been forced to use the AC unit much. However, last summer I was in South Dakota in 100 degree heat. I pulled into my cousin's farm yard and we plugged the T@G in and fired up the AC. It was not working in a stellar fashion. Then he looked at me and said, "You know, I have a completely air conditioned house and a spare bedroom 25 yards from here. Why would you stay out here? I'm in to suffering but my cousin's logic trumped the T@G AC that evening. But what about when I want to go to some sweltering place like Missouri or Kansas? I have grandchildren in Kansas of all places. Have you been in Kansas? That is like an oven.
I need help.
NathanB

Geoff_Acker

We took our TAG out for the first trip this weekend and I was not impressed with the performace with the AC. It cooled the cabin down to between 70-72 degrees. But the humidity was a real issue. The humidity level got up to above 80%. I believe that was higher than the actual outside humidity. We ended up just turning the AC off and using the ceiling fan which made it much more comfortable. When we got home I did some investigating and removed the wood trim around the front of the AC. What I saw on the tops and sides of the unit seemed to be very shoddy sealing with foil tape. I have included a pic of the top of the unit where it connects (or doesn't connect) with the insulated duct in the back. I cant tell if the duct is supposed to be firmly taped to the top of the unit or if it's supposed to be stuck up as it appears in the picture to allow hot air from the top of the unit to be sucked down the back. In any case, hot air being blown out the back was reflecting back at my face as I was looking through this small horizontal sliver. I put my hand back as far as I could and again felt extremely hot air being blow back towards the cabin. The sides of the AC also had foil tape stuck to them as if the insulation board had once been sealed/taped around the unit in the back but had pulled away, which again, let hot air flow back towards the cabin. I don't know, I will be sending this pic to nucamp as well. Anyone else have seen anything similar in their TAG?

TennTim

@nbrandt I dont know the placement of the fans, but I would offer that you want the fans sucking the air out of the back placing the duct in a negative draft. Given the two choices of sucking air from the cabin into the duct or blowing the hot and humid air from the duct into the cabin, I would go with the former. I agree that going with the flow of natural convection up makes sense, but it’s not hard to overcome and if the fans are near the bottom, sucking the duct and blowing down is preferred.

Again, I would rather them stay separated. We don’t cool 100 ton chillers at work by using the chilled glycol they created. We would be spinning our wheels thermodynamically (and could have bought a 50 ton chiller, with proper cooling). We use fans or cooling water to “reject the heat.”

A/C (in fact all refrigeration) works by “pumping heat” across zones. A “heat pump” if you will. Coolness cannot be created, the heat must be moved across the boundary, often through the use of a boiling/condensing refrigerant as in this case. If you cooled something off, something else is hotter by a greater amount (dang thermodynamics again not even letting you break even!). Think of the times you felt a hot air compressor tank after running and a cold air duster can as you sprayed, that’s the principle of refrigeration, except the vapors and liquids are pumped around.

That ductwork should be sealed up tight from the cabin. Now you might be able to rationalize that these AC units are so oversized that you could use some of the air flow to sweep the sides but you’re risking over doing it, thus my thought to have adjustable dampers on those round vents. I would need to do some thinking, but even in that scenario, I don’t think it’s a net positive. Best case is probably adding some baffling to force the air in the duct to where it needs to go and/or another fan to get it where it is desired.

OutdoorEd

I really don't have much to contribute to this thread. But, I did want to say that we have had no issues with our AC unit. For 2 seasons, it has cooled quickly and maintained comfortable temperatures whenever it's been called upon.

rich67

I can ditto OutdoorEd's reply, and add that in Florida heat and humidity (92 degrees the other weekend) in the bright sun, the temp in my Tag XL got down to 68 during the day, and was in the upper 50's at night (yeah, that was just a test and man it was cold). I do notice an issue with humidity, and I also notice an issue with the vents blowing right on us at night. The air can be diverted with a product off Amazon, but the humidity is another issue. I can only say I think I am going to look into purchasing a different unit that will fit in there, specifically one with a digital thermostat control and with heat as well. Anyone tried that yet?

Vonbrown

I have removed the A/C unit and installed t into the passenger side window. Seems to work better but because the unit is to big, it doesn't cycle long enough to remove the humidity. I turn the thermostat all the way up, open the roof vent a bit and can get comfortable.