"The X-Cubed" C.T.T.

...ask your questions in the appropriate forums BUT document your build here...preferably in a single thread...dates for updates, are appreciated....

Re: "The X-Cubed" C.T.T.

Postby bdosborn » Thu Jul 13, 2017 6:56 pm

There's no replacement for displacement, step up to a 200MM computer fan. :thumbsup:

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Looking forward to your next build.
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Re: "The X-Cubed" C.T.T.

Postby Alan_H » Thu Jul 13, 2017 8:02 pm

absolutsnwbrdr wrote:...
Oh, and this X-Cubed project really needs to come to a close, as there is a new one looming...
Say hi to our 1976 Serro Scotty 13' Gaucho. Poor girl's bones are rotted away and she's in need of a complete frame-off rebuild, but all the skins, trim, lights, windows, and hardware are there and in great condition. :twisted:

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How much does the Scotty weigh? :thinking: If I remember right, the XV is only rated to tow 2,000 lbs, and 200 lb tongue weight.
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Fri Jul 14, 2017 8:34 am

bdosborn wrote:There's no replacement for displacement, step up to a 200MM computer fan. :thumbsup:

Amazon Linky

Looking forward to your next build.


:thinking: :thinking:

I really cringe at having to go back and cut in larger holes, especially since I have my exhaust covers mounted. And the specs on that particular case fan says 110cfm? I guess that could be right, but that's not much more than the 120mm fan I just ordered. I wonder what kind of pressure they can push... I bet that's probably quite a bit higher.

I was also trying to avoid larger fans because of their thickness. 120mmx120mmx25mm fans are only 1" deep so they fit in the thickness of my wall, which means I can't knock into them dragging coolers in and out of the galley. If I have to step up to an "extreme" high speed 120mm fan, they'll still fit in my square opening in the wall, but they are then 38mm (1.5") deep, which will protrude into the galley 3/8". Not ideal, but that I could probably live with. Oh the choices! :?
Last edited by absolutsnwbrdr on Fri Jul 14, 2017 9:17 am, edited 1 time in total.
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Fri Jul 14, 2017 9:13 am

Alan_H wrote:How much does the Scotty weigh? :thinking: If I remember right, the XV is only rated to tow 2,000 lbs, and 200 lb tongue weight.


The plan right now is to tow it with the Crosstrek, but my girlfriend has a Jeep Renegade Latitude, rated to tow 2000lbs, so we may end up putting a hitch on that.

The little gerbil that powers the Crosstrek is only rated (in the US of A) to tow 1000lbs (or 1500lbs if the trailer has brakes), and 150lb tongue weight. Admittedly, the X-Cubed has probably been a hair over 1500lbs on a couple occasions, and it does not have brakes. Slow and steady on those trips. I definitely feel it back there going up steeper inclines, but in 4 years, I've never had any issues, and have not once felt out of control. I don't mean to gloat but the weight balance on the X-Cubed is top notch, and tows like its on rails. 8)

The factory specs on the Scotty claim a dry weight of 975lbs, and it does have electric brakes. The focus on rebuilding will be to maintain relatively light weight, but with better materials and sealants. The kitchenette and wardrobe will be 6" narrower to accommodate a double size bed rather than a twin, while the rest of the layout remains orignal (new materials). By the time its all said and done (batteries, propane tanks, etc), I expect a dry weight similar to the X-Cubed (1280lbs), and hopefully with working brakes. Obviously I will have to install a brake controller on either the Crosstrek or Renegade.

Ultimately, I will be trading in the Crosstrek, on Subaru's yet-to-be-released full size SUV - the Ascent. Then there will be absolutely no questions about towing the Scotty or X-Cubed :D
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Re: "The X-Cubed" C.T.T.

Postby Alan_H » Fri Jul 14, 2017 9:47 am

I'm looking forward to seeing specs on that, as I now have a '16 Forester XT. I am also limited to 1500lbs towing with brakes. I have a Dexter torsion axle with brakes for my upcoming build.
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Fri Jul 14, 2017 10:19 am

Alan_H wrote:I'm looking forward to seeing specs on that, as I now have a '16 Forester XT. I am also limited to 1500lbs towing with brakes. I have a Dexter torsion axle with brakes for my upcoming build.


Thats unfortunate... Forester used to be able to tow 2400lbs (until it was reduced in 2014). If the Ascent is to compete in that range of vehicles with the Explorer, Cherokee, etc, then Subaru will have to give it more power and towing compared to the Outbacks' 2700lbs towing capacity. Unfortunately for me I can't see myself driving anything other than a Subaru. Its all I've ever owned. Ive always enjoyed the reliability and safety, and I feel the brand does actually care about their customer base, not just sales figures. You don't see them getting into pissing contests with other manufacturers... they just do their own thing and do it well. They've always been a bit eclectic, usually not the most attractive, but they are typically solid vehicles.

I'm considering replacing the original spring-torsion axle on the Scotty with a modern Dexter torsion, and would definitely order with brake flanges. I've even thought about selling the Dexter torsion on the X-Cubed and ordering a new one with brake flanges. I should have done that in the beginning, but didn't think it would be necessary. Live and learn!
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Re: "The X-Cubed" C.T.T.

Postby bdosborn » Fri Jul 14, 2017 11:42 am

A 200mm is typically around 40% more airflow over a 120mm fan of the same manufacturer BUT at around the same noise level. The high CFM 120mm fans get loud. But I hear you about cutting bigger holes, I cringe too whenever I have to do it.
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Re: "The X-Cubed" C.T.T.

Postby working on it » Fri Jul 14, 2017 11:55 am

absolutsnwbrdr wrote:Finished getting the exhaust vent covers installed...

However....

I put the A/C in the camper to test the venting, and I have to unfortunately chalk up this initial attempt as a fail. Each of the two computer case fans move (supposedly) 64cfm, which isn't near enough. They definitely kick the hot air out my exhaust vents, but not fast enough. I put a thermometer inside the lower galley, closed the galley hatch, and let the A/C run for a while. The teardrop cooled off very nicely.
But within a couple hours the ambient air temps in the lower galley were up around 120°f. :oops:

The two fresh air intakes in the floor seem to be more than large enough, as there isn't a rush of air going in, but rather a calm steady flow. Which leads me to believe that my fans just don't move enough air. I've ordered two new 120mm fans, each rated at 103cfm, which should be here Saturday. If these don't do the trick, I'll need to play around with other options, possibly utilizing a fan in one of the intended fresh air floor intakes as an exhaust fan. Having 3 exhaust vents and one intake vent would certainly increase air velocity, which may be just what I need.

"I have not failed. I've just found 10,000 ways that won't work."....
  • My A/C system also failed, at first (actually, several times), due to thermal overload, like yours. I was trying to capture the A/C exhaust in a metal vent boot (used in hvac), directing it thru insulated ducting to exit thru a wall vent on the other side of my galley, so I could run it at night, with the hatch closed. The problem I faced was that the hot exhaust air wasn't exiting fast enough, but building up in the ducting. After several re-builds of my ducting, I finally enlarged the exit hole to 6" (from 5"), eliminated any internal restrictions (straightened the ducting), and installed an axial duct fan inside the duct. http://www.tnttt.com/viewtopic.php?f=21&t=54945&hilit=+solved#p999038
  • I used a 6' diameter axial fan, chosen because it was the right size for my ducting, had a high flow rating, and was rated for high heat tolerance.I'm not quite sure of the exact configuration of your A/C system, or of any size restraints for adding a larger, more powerful fan (except that the outlet must match your already mounted exterior vent cover), but I have two alternatives that may work for you, by removing the hot air faster.
  • 1) follow my build's example, using an axial fan: it will have to be mounted directly to your wall, so using a different type of Speedi-boot is suggested, placed over the wall opening, with the fan screwed into the collar, using sheet metal screws.
  • speedi-boot.PNG
    speedi-boot.PNG (165.32 KiB) Viewed 545 times
    centered over the wall opening, with fan attached to the rear
  • axial fans hi-flow, hi-heat.PNG
    axial fans hi-flow, hi-heat.PNG (149.34 KiB) Viewed 545 times
    I used the 6" fan in my system
  • 2) directly mount a centrifugal fan to the wall: would be a more direct approach, with higher air flow, but with less thermal resistance to overload. 140 degrees will shut these fans off (compared to 250+ degrees of the axial fans), but you've only seen 120 degrees, and I only saw 140 once (with major restrictions to the flow), but only once, so the 140 degree rating would probably work for you.
  • centrifugal fans higher-flow, more heat sensitive.PNG
    centrifugal fans higher-flow, more heat sensitive.PNG (115.61 KiB) Viewed 545 times
    easier install, maybe better for the open (unducted) system
  • I bought my axial fan on e-bay, but later found the manufacturer's website http://www.aero-flo.com/. I like the fact that their products are made in the USA, and my fan solved my A/C situation, and might solve yours, so it's a suggestion you might want to consider. Good luck!
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Fri Jul 14, 2017 12:35 pm

Thanks for the info guys! Part of my dilemma is the desire to not have ducting taking up space (and being more work to take the AC in and out), but that may be the only way to efficiently handle the hot air. I was hoping I'd get enough air flow just with multiple openings, but may need more fans, or more openings to make it work. :?
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Re: "The X-Cubed" C.T.T.

Postby Dirtclod » Fri Jul 14, 2017 1:04 pm

I am also watching this thread very closely as I did something very similar in my build, only I did just the opposite. Cool Air through the side wall with a PC fan and a shroud to direct the heat through the bottom of the trailer. I am still in the build stage and haven't really run this setup for more than a few minutes in the garage.

ImageUntitled by MIke Burkeen, on Flickr

ImageUntitled by MIke Burkeen, on Flickr

Since you need lots of airflow .. how about a 12 V radiator fan? This one is supposed to flow 1750 CFM.

https://www.amazon.com/dp/B00T3T7IJU?psc=1

If my setup doesn't work out I plan on making somes ort of external setup that I can use a bigger fan like this. We will see how it goes.
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Re: "The X-Cubed" C.T.T.

Postby working on it » Fri Jul 14, 2017 3:30 pm

Dirtclod wrote:I am also watching this thread very closely as I did something very similar in my build, only I did just the opposite. Cool Air through the side wall with a PC fan and a shroud to direct the heat through the bottom of the trailer. I am still in the build stage and haven't really run this setup for more than a few minutes in the garage.

ImageUntitled by MIke Burkeen, on Flickr

ImageUntitled by MIke Burkeen, on Flickr

Since you need lots of airflow .. how about a 12 V radiator fan? This one is supposed to flow 1750 CFM.

https://www.amazon.com/dp/B00T3T7IJU?psc=1

If my setup doesn't work out I plan on making somes ort of external setup that I can use a bigger fan like this. We will see how it goes.
  • Electric radiator fans are really loud. When I was building the interior of my TTT, I tried using a 10" fan I had leftover from my dragracing days. I mounted it hanging under my overhead shelf on a swinging bracket. But, it was insanely loud in my 4x8 trailer, and ate up lots of 12vdc battery power. So, I used a 120vac Honeywell air circulator (3-speed, using low amps) instead. The automotive fan might work OK as an exhaust fan, provided that the enclosure was fairly well soundproofed, and of course, you used an inverter to convert 120vac (I'm assuming you would run the fan on the same switched circuit as the A/C is on; I do) to 12vdc for the radiator fan.
  • The Aero-flo fans I recommended are 120vac already, and the one I use, the axial 6" fan, is fairly quiet, especially being on the other side of my rear bulkhead, wrapped in a fiberglass insulated duct. When the A/C cycles off, /i can just barely hear it working back there, so it's just "white noise" to me. But, in a trailer with insulated walls, a radiator fan might just be quietened enough.
2013 HHRv"squareback/simple" TTT, semi-offroad? 4x8, <2000 lbs travel weight
  • 3500 lb Dexter axle w/brakes,
  • 27x8.5-14LT all-terrain tires (x 3),
  • LED lighting, triple fans. stereo inside,
  • A/C & heat, Optima AGM, inverter & charger(s)
  • extended-run, on-board, 2500w generator,
  • Coleman dual-fuel stove & lantern,
  • zinc/stainless steel front rack
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Sun Jul 16, 2017 8:01 pm

Dirtclod wrote:I am also watching this thread very closely as I did something very similar in my build, only I did just the opposite. Cool Air through the side wall with a PC fan and a shroud to direct the heat through the bottom of the trailer. I am still in the build stage and haven't really run this setup for more than a few minutes in the garage.

ImageUntitled by MIke Burkeen, on Flickr

ImageUntitled by MIke Burkeen, on Flickr

Since you need lots of airflow .. how about a 12 V radiator fan? This one is supposed to flow 1750 CFM.

https://www.amazon.com/dp/B00T3T7IJU?psc=1

If my setup doesn't work out I plan on making somes ort of external setup that I can use a bigger fan like this. We will see how it goes.


Wish I had seen your posts before now... This is what I should have done from the beginning! Friday night I was out in the garage and put a cardboard box on the back of the AC to direct the air out the bottom, rather than in. And it seemed to work. My new fans arrived Friday, so all weekend I've been working on the final solution! I've been testing it since yesterday and I'm good to go!!

Just needs some paint. :twisted:
Last edited by absolutsnwbrdr on Sun Jul 16, 2017 8:17 pm, edited 1 time in total.
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Sun Jul 16, 2017 8:07 pm

As I've mentioned, when camping in cooler weather the air conditioner stays at home. So I made filler plugs for the vent openings in the floor. And they blend in so well. :D

Image

Image

To install the air conditioner, the plugs come out of both floor openings and my new dual exhaust fan assembly (two 120mm, 100cfm computer case fans) fits in the larger floor opening. Then the air conditioner cradle fits in the bulkhead opening, and the air conditioner rests on that. To collect the hot exhaust from air conditioner, a box cover fits over the back of the unit, directing air out the bottom of the trailer. Fresh air is drawn in through the vents in each side of the camper.

Image

Image

Image

Image

While traveling with the air conditioner, the exhaust box cover slides up onto the air conditioning unit, leaving enough room for a cooler.

Image

Image

The "exhaust" holes and covers on each side wall of the camper are now "intake vents", and I don't have and power running to those fans right now. The force of the two fans out the bottom of the galley floor draws enough air through the air conditioner that there is actually air flow in the side vents. Galley temps hang right around ambient air temperature and the air conditioner cools the camper well. Woohoo!
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Re: "The X-Cubed" C.T.T.

Postby Alan_H » Sun Jul 16, 2017 8:13 pm

Cool!!! :applause:
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Re: "The X-Cubed" C.T.T.

Postby absolutsnwbrdr » Sun Jul 16, 2017 8:18 pm

Alan_H wrote:Cool!!! :applause:


Literally! :lol:

Now I just need to pack for Crossroads of America Gathering.... Wednesday morning will be here fast!
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