Installing a minisplit in a 78 Caravanner

[TouringDan]

We went to Fort Worth, Texas to do some work on our son and daughter-in-law’s 78 Caravanner. They have been using it as an aluminum tent, so there was lots to do.

We didn’t get all the minisplit installed, but we did get the cabinet built and installed and did attach the air handler to it. I would like to say the work to do this was straight forward but when you are doing something for the first time, nothing is straight forward.

The face and cabinet sides are 1/2” birch plywood, the bottom (not installed yet) will be 1/4” plywood. No interior photos of the structure yet. I will take some when I return to Texas in 2-3 weeks to finish the job.

While it looks like it is just installed in the middle of the wall, there will be a 10 cubic foot compressor fridge installed next to the air handler.

I had to remove all the propane tank stuff to make room for installing the outdoor unit on the tongue. I then installed the 16x24 x1/4” mounting plate on the A frame. I secured it with 3/8 x 5.5” SS bolts. 5” bolts would be long enough for the 4” frame material. I didn’t really have the right tool for cutting the aluminum plate but I did the best I could with a 4.5” grinder and a jig saw. I suppose a band saw would work better.

Installing the 8mm stud insulators was initially a problem- I didn’t know how I was going to do it but then the solution came to me about 4 in the morning. I just drilled and tapped a hole in the aluminum plate and in the top of the frame. I then threaded the insulators into the hole. I wasn’t smart enough to think about using thread lock before I installed them (thanks Bubba L) but I will do this when I return. The unit is also just slightly touching the jack head. I will install some fender washers on top of the insulators to “tilt” the unit slightly to provide adequate clearance.

The distance from the compressor to the shell is 11”. This will allow room to install a 10 Lb horizontal aluminum propane tank as it requires 10 3/8”. This will be installed on another aluminum plate on top of the A frame. I believe 10 Lb of propane will be fine as it only will be needed for cooking and hot water. The minisplit provides good heat so we will be removing the furnace.

Any comments and questions welcomed.

Dan

[Bubba L]

Dan, I think the design looks to be well thought out and functional. I think you’ve designed/installed the wave of the future HVAC system for RVs, the mini split. Keep us posted on your progress. Take care

[TouringDan]

Well I finally returned to Fort Worth to finish the installation of a mini split in a 78 Caravanner. I didn’t show the detail in previous photos but I secured the cabinet to the ceiling with 5/32 long rivets and #12 x2” sheet metal screws.

Installation of the drain line was pretty simple. I just ran it straight down the wall and through the wheel well.

Dan

[TouringDan]

Next and probably the most difficult was installing the refrigerant lines. The most difficult part was that I had not ever done this before. There will be a refrigerator just to the right of the air handler cabinet. To the left of the refrigerator bulkhead the refrigerant lines need to stay low below the height of the wheel well. To the right of the bulkhead the refrigerant lines need to stay in the cavity behind the refrigerator.

Once the refrigerator is installed and the wheel well is covered all the refrigerant lines visible now will be completely hidden.

The big question was where and how to penetrate the floor. I started the penetration behind the location of the fresh water tank and then went on a shallow angle toward the back. I decided to install some 1.25” tubes to contain and protect the refrigerant lines.I ran the control wiring just above the tubes. I located the wiring in piece of rubber hose to protect the wire from being cut by the sheet metal.
Installing the 1/2” refrigerant line in the conduit was difficult. I had to install the insulation and then run the wire. It took 1.5 hours. Installing the 1/4” line was easy. It took 5 minutes.
The refrigerant lines run underneath the belly pan and then connect to the outdoor unit.

I knew the standard length of 16 ft for the refrigerant line was not going to be enough. I ordered a 25 ft line set. I decided to connect the factory end of the refrigerant line to the outdoor unit. I then needed to cut off about 3 feet of line and make new refrigerant line flairs to connect to the indoor unit. This isn’t real easy as a quality flair is important to the performance of the minisplit.

I made all my connections, torqued the flair nuts down properly and vacuumed the refrigerant lines and started the unit up. It started cooling immediately. Winthin an hour the interior temperature dropped from 91 to 72F.

Just as important as the cooling performance, the unit was quiet. The outdoor unit measured 47 dB about 10 feet away. It really is just a quiet hum.

The indoor unit was just 43 dB, incredibly quiet. When I turned the unit off the noise level dropped to just 36 dB. You really need to listen for yourself to appreciate how quiet the minisplit is.

Dan

[OTRA15]

Originally Posted by Bubba L

Dan, I think the design looks to be well thought out and functional. I think you’ve designed/installed the wave of the future HVAC system for RVs, the mini split.
. . .

I concur, as mentioned on your other threads Dan, nice work!

One possible weak link in the chain, however, when on the road, might be having all that weight cantilevered fairly far removed from the fasteners holding the entire assembly to the curved wall/ceiling IMO.

When bouncing down a rough road, the gravitational forces of that cantilevered weight, at the end of a long "lever," may challenge the fasteners IMO, which have very small bearing surfaces on the fixed frame material [screw threads, rivet washers etc.].

For severe off-road bouncing, may I suggest some kind of temporary vertical support under the most interior projection of the whole mass? Some temporary mechanical clips might accomplish this at the top and bottom of a minimal vertical post.

Thanks for all the detailed photos, good planning and engineering, and great thinking!

Peter

[TouringDan]

Thanks for your comment Peter. I share your concern. I am hoping that the heavy duty installation of the cabinet will be adequate.

I have also recommended that new axles and shock absorbers be installed to minimize the stress on the fasteners.

When the new refrigerator is installed the bulkhead adjacent to the left side of the refrigerator will be connected to the right side of the cabinet thus providing the vertical support you are recommending.

Dan

[OTRA15]

Originally Posted by TouringDan

Thanks for your comment Peter. I share your concern. I am hoping that the heavy duty installation of the cabinet will be adequate.

I have also recommended that new axles and shock absorbers be installed to minimize the stress on the fasteners.

When the new refrigerator is installed the bulkhead adjacent to the left side of the refrigerator will be connected to the right side of the cabinet thus providing the vertical support you are recommending.

Dan

Great! That should do it . . . thanks for the update.

Peter

[dbj216]

Wow! What a project. Bubba L is right. It likely will become the future of RV air conditioning. The roof top units are so inefficient and noisy. The ducted air versions are a bit better for noise.

We have a "mini split" in our home. Our house is older with hot water heat, no ducts. So the air conditioner compressor is outside next to the house and the compressed refrigerant is pumped to the attic (evaporator) and blown through ductwork and out the ceiling. The system works good and we are satisfied with the "investment" as the gvmt likes to say.

Very impressive cooling power of the unit, and low noise level. In Texas as well as Colorado, cooling is a welcomed luxury. But like you said, we are sucking hot air out of the trailer and dumping it outdoors. Most buildings, homes, and vehicles have them.

David

[TouringDan]

Well I am really not done yet with the installation. I wanted to add some more insulation to the refrigerant lines so I wrapped it with 1/8” X 2.8” foam rubber (from Amazon). I then wanted to wrap this with 1.5” plastic wire loom (like Bubba L. did), but could not find any locally in Fort Worth, so I gave up and just ordered 100 ft from Amazon. I went ahead and covered the newly insulated lines with Gorilla duck tape until I can install the plastic wire loom.

I was also concerned that hitting a large bump in the road might move the air handler up and off the cabinet support, so I installed a piece of wood on each side that would prevent this from happening.

Dan

[TouringDan]

After performing a noise test with the minisplit operating in the 78 Caravanner, I thought about how this might compare with a similar test for a new Airstream with ducted air. This would be most accurate if I performed the test using the same equipment (IPhone app). Well I was only about 10 minutes from the DFW Airstream dealer. I drove over there and found a 2021 Flying ready to be delivered and connected to shore power. This is truly a beautiful
Airstream. I asked the technician if he would mind showing me how quiet the ducted air conditioning was. He turned it on and it really is quiet though not as quiet as the minisplit. The noise level was 55 dB. I would be comfortable spending time in either noise level environment.

Dan

[dbj216]

There is nothing like good data to demonstrate an improvement. What is the total weight of the mini-split system? It looks big in the photos.

David

[TouringDan]

Originally Posted by dbj216

There is nothing like good data to demonstrate an improvement. What is the total weight of the mini-split system? It looks big in the photos.



David

David- Thanks for asking. The minisplit outdoor unit on the tongue weighs about 88 lbs with the indoor air handler weighing about 22 lbs for a total of 110 lbs. I believe this is about the same as an RV air conditioner. Add maybe 15 lbs for the aluminum support plate and refrigerant lines and 10 lbs for the propane tank then subtract 60 lbs for the two propane tanks removed and 40 lbs for removal of the furnace equals a net weight loss of about 75 lbs. I might be off a little bit in my estimate. The weight is also carried lower which is a distinct advantage.

Dan

[dbj216]

Well, that all worked out well for the Caravanner; quiet cooling and warming with less weight. Well done.

David

[TouringDan]

I just wanted to report that after a season of camping in Texas to Arkansas to Florida the minisplit performed flawlessly.



Dan

[Por Sonia]

Thanks for the update . . . well done!

Peter

[Bubba L]

Glad to hear the good report. After a few trips I check the isolator bolts and connections. So far, so good. Keep us posted.