Mini split A/C system

Topic: Mini split A/C system (Read 4447 times) previous topic - next topic

Mini split A/C system

July 06, 2021, 12:37:50 am

Has anyone replaced their rooftop air conditioners with a mini split A/C system ?

Re: Mini split A/C system

Reply #1 – July 06, 2021, 08:07:13 am

There are several threads on other boards concerning this.

Basic pros are first, they seem to cool better. There is some suspicion that the minis are required to be accurate in their ratings while the RV ACs may be fudging a little. Second, they use less electricity when measured in the real world. Again, some suspect the ratings are being shaded a little.

The cons are they may be hard to mount, both from finding a good location to finding a hardpoint strong enough to support the interior unit while bouncing down the road. Second, finding a well ventilated location for the condenser that is aesthetically pleasing is a problem., Third, they need to be close to level while in operation so the condensate drains properly. Forth, and this seems to be the biggest problem, the units are really not meant to be on moving vehicles. Meaning the construction is not robust enough to stand the rigors of transport.

All of that said, people who find away to be content with the cons seem to be VERY happy with the minis in general and extremely happy with the performance.

The most offered advice for a newbie is to make sure the installation is as robust and protected from vibration as possible.

TOM

Re: Mini split A/C system

Reply #2 – July 06, 2021, 08:17:49 am

It's a shame that RV ACs are basically the same old technology today as they where over 20 years ago. If any thing comes along Dometic and Coleman buy em up and quit making them .

Re: Mini split A/C system

Reply #3 – July 06, 2021, 08:44:58 am

The newest technology in RV roof airs is separate fan motors for evap and condenser. That's about it. It does make a small difference in noise though.
Watch the Australians though, I think there might be someone down there who is making an inverter style roof A/C. But IMO D. and C. are too large to let anyone else disrupt their market share.

Re: Mini split A/C system

Reply #4 – July 06, 2021, 12:17:55 pm

My stop has been mounting the interior unit . And running the cords/ drain.
The best place is under the couch and that means blowing cold air at your ankles. Outside unit in grille.
The next best location is above the bed , running the cables down the inside of the rear cap. The out side unit mounts where the muffler was.
The new mini are seer 23 or more at very quiet noise levels.
The OE overheads might be seer 10.

Re: Mini split A/C system

Reply #5 – July 06, 2021, 02:22:21 pm

I appreciate the quick replies. If the problems that OldManSax listed can be solved, the split mini A/C system would really go well with the coaches with a lot of solar panels.

Re: Mini split A/C system

Reply #6 – July 30, 2021, 03:49:16 pm

I have seen youtube vids about people who have done this, it certainly is intriguing.

However, I just went though this with installing HVAC in my shop. I started out looking at Mr Cool units and then other brands. In short, there are 2-3 top brands, the rest are junk. I had numerous estimates and more than 1 HVAC installer tell me that you may not be happy with the end results here in Texas.

The other thing is parts. HVAC techs don't carry these on their truck so if something is needed, it has to be ordered, and have seen people wait up to 4-6 months. No thank you.

In the end, I put in a 5 ton Carrier in the shop, it was cost less than 2 minis and performs wonderfully. On our FT, the dual ACs have been replaced with Dometic's that are about 2 years old and they will freeze you out.

YMMV.

Re: Mini split A/C system

Reply #7 – July 30, 2021, 04:14:48 pm

Installed a Friedrich inverter mini split in Kingsville TX. about 7 years ago,ran fine no problems,one reason the shops don't like them is no labor intensive ductwork to install,they've been in Japan for decades.

Re: Mini split A/C system

Reply #8 – July 31, 2021, 10:46:42 pm

I love my Mr cool mini in my house . Super quiet , super efficient.
Still looking for the Best interior placement for the Mini for the bus.
Possibly under the counter where the booth used to be.
I would never install a central ac in the attic any more , here in Fl. Way too much loss and no where near the sear values of the inverter minis .
The operating cost are almost exactly half of last years bill .

Re: Mini split A/C system

Reply #9 – August 27, 2021, 11:12:19 pm

Update; I found the places with room for the Minisplit . Right in the nose for the outside unit, in place of the OE Condenser. 50 ft of lines to run to the bedroom upper cabinet . The lines should fit inside,/between the cap and inner panel . . I just cant stand the thought of running the lines down the walls or exposing the condenser outside . This should work out and keep the bedroom cool and quiet .
With the inverter electrics along with seer 19 , maybe this will run off of batteries for a short bit . I'm not sure what the loss will be with 50 ft of lines , but they are a common option so it must not be too much.
Next to trial run some rope and see how long 50 ft really is .

Re: Mini split A/C system

Reply #10 – August 28, 2021, 02:55:34 am

Quote from: Protech Racing – July 31, 2021, 10:46:42 pm

I love my Mr cool mini in my house . Super quiet , super efficient.
Still looking for the Best interior placement for the Mini for the bus.
Possibly under the counter where the booth used to be.
I would never install a central ac in the attic any more , here in Fl. Way too much loss and no where near the sear values of the inverter minis .
The operating cost are almost exactly half of last years bill .

Mike, Did you install your Mr Cool in your house yourself "DIY"? I watched few videos and I am thinking about installing a 4/5 ton universal model in my shop. Also a 9K version for our office.

Re: Mini split A/C system

Reply #11 – August 28, 2021, 06:27:43 am

Installed a couple by ourselves,if you have access to a leak detector it helps after the install.

Re: Mini split A/C system

Reply #12 – August 28, 2021, 10:22:59 am

I installed a 24K BTU (20 SEER) Mr. Cool in the house two weeks ago. Very impressed with the unit. My biggest challenge was running new conduit and wire for the 220V power disconnect. The only short coming of the Mr. Cool unit was the length of the line set. They include a 25' set and I only needed around 16'. This forces you to coil the excess ( I did mine horizontally to prevent oil traps). Good system.

jk

Re: Mini split A/C system

Reply #13 – August 28, 2021, 12:34:22 pm

This is the video I saw of the guy that removed the roof A/C's and replaced with a mini split in his FT. He gives up one compartment for the condenser...which went where the propane tank was (he removed it). Also, it sounded like the output from the two head units (front and rear) were each less than the roof units. Something like 12k and 9k.

https://youtu.be/2napX5XnOTk

Re: Mini split A/C system

Reply #14 – August 28, 2021, 01:01:02 pm

Quote from: propman – August 28, 2021, 02:55:34 am

Mike, Did you install your Mr Cool in your house yourself "DIY"? I watched few videos and I am thinking about installing a 4/5 ton universal model in my shop. Also a 9K version for our office.

Yes, The biggest issue is finding a good place for the hole to exit the house. My house is concrete block and I got lucky measuring form the edges of a block ,to hit the correct spot in the block . Trying to avoid a solid area.
The other issue is that we needed to drain it left and the instructipns said X while in reality I had to tip it to 1/4 in to drain.

Most of the 9-12K outside units are 21in tall. This is a problem for my short bus. My area under the bedroom is only about 17 to the bottom edge of the bodywork . The grille is no problem .

Re: Mini split A/C system

Reply #15 – August 28, 2021, 01:50:33 pm

Hi All, I thought I should share an update. I was going to wait until I had it completely installed, but I ordered the wrong line set and am waiting on the correct one, so it isn't operational yet. The plan includes added splash guards and mesh to protect from flying rocks, but that hasn't happened yet since the install isn't complete. I made a rack out of 3/16 steel and mounted it by drilling and tapping 5/16" holes in the frame. I did loose a little clearance, but I don't think it will be a problem. The pictures are at:
Mini-Split

In case your wondering, the coach currently is stilling up on stands in the suspension for access.

Re: Mini split A/C system

Reply #16 – August 28, 2021, 02:35:28 pm

This looks awesome!

Do you have to take the dash AC out?

Please keep updating your project.

Quote from: rvtinker – August 28, 2021, 01:50:33 pm

Hi All, I thought I should share an update. I was going to wait until I had it completely installed, but I ordered the wrong line set and am waiting on the correct one, so it isn't operational yet. The plan includes added splash guards and mesh to protect from flying rocks, but that hasn't happened yet since the install isn't complete. I made a rack out of 3/16 steel and mounted it by drilling and tapping 5/16" holes in the frame. I did loose a little clearance, but I don't think it will be a problem. The pictures are at:
Mini-Split

In case your wondering, the coach currently is stilling up on stands in the suspension for access.

Re: Mini split A/C system

Reply #17 – August 28, 2021, 02:39:08 pm

No, the dash unit is undisturbed, though I haven't bothered to get it working yet. It was converted to R134A by a previous owner so I don't think it will be too big a deal. Life has been doing a good job of getting in the way of my Foretravel project.

Re: Mini split A/C system

Reply #18 – August 28, 2021, 05:26:55 pm

Would like to see how the "rear" unit is mounted and keeping the water out of the belly of the beast (bulkhead)

Re: Mini split A/C system

Reply #19 – August 28, 2021, 06:03:47 pm

If by the "rear" you are referring to the outside unit, I managed to forget to photograph the mounting frame before I installed it. I just mocked up the outside unit from light wood and then moved it around until I found a space where it would fit. I then welded up the frame from 2x2x3/16 steel (massive overkill). I rigged the frame into the correct position, then devised brackets to attach it to the chassis. I drilled and tapped 5/16" holes to hang it, and test fit it with the mockup. Once it fit I painted it and installed the unit on the frame on rubber isolators, then wiggled the assembly into place and bolted it in.

The plan is to use mud flap material and corrugated plastic sheet to make a kind of wheel well/splash guard between the right from wheel and the outside unit. Expanded metal sheet will be used to make rock guard protecting the two sides of the unit. An additional small splash guard will go on the front to protect the section the stick out below the nose.

The line set will be routed through the right front overhead cabinet, down the wall next to the passenger seat, under the passenger platform and then through the floor to the unit. A new 12 ga Romex feed has been run from the breaker panel up the left side under the cabinetry. It is awaiting the line set to be routed into the unit.

Re: Mini split A/C system

Reply #20 – August 29, 2021, 04:01:59 pm

Quote from: propman – August 28, 2021, 02:55:34 am

Mike, Did you install your Mr Cool in your house yourself "DIY"? I watched few videos and I am thinking about installing a 4/5 ton universal model in my shop. Also a 9K version for our office.

Quote from: John44 – August 28, 2021, 06:27:43 am

Installed a couple by ourselves,if you have access to a leak detector it helps after the install.

We installed a small unit for an upstairs bedroom. I thought the process was pretty straight forward and had no issue doing a self install even though I had never installed one before.

The evaporator came pressurized with nitrogen so when you remove the caps, if there is still pressure you know the evaporator is not leaking. The condenser comes pre charged with the refrigerant which you release into the line set and evaporator after the install.

As an alternative to charging the system and using a detector to find leaks, charge the line set and evaporator with nitrogen. Let it set for several hours. If it leaks down, use soapy water on connections to find the leaks and make the system leak free, then use a pump to evacuate the system before releasing the refrigerant. There are really on four places one can leak...the connections at each end of the line set.

Re: Mini split A/C system

Reply #21 – September 07, 2021, 01:19:46 pm

Quote from: rvtinker – August 28, 2021, 06:03:47 pm

If by the "rear" you are referring to the outside unit, I managed to forget to photograph the mounting frame before I installed it. I just mocked up the outside unit from light wood and then moved it around until I found a space where it would fit. I then welded up the frame from 2x2x3/16 steel (massive overkill). I rigged the frame into the correct position, then devised brackets to attach it to the chassis. I drilled and tapped 5/16" holes to hang it, and test fit it with the mockup. Once it fit I painted it and installed the unit on the frame on rubber isolators, then wiggled the assembly into place and bolted it in.

The plan is to use mud flap material and corrugated plastic sheet to make a kind of wheel well/splash guard between the right from wheel and the outside unit. Expanded metal sheet will be used to make rock guard protecting the two sides of the unit. An additional small splash guard will go on the front to protect the section the stick out below the nose.

The line set will be routed through the right front overhead cabinet, down the wall next to the passenger seat, under the passenger platform and then through the floor to the unit. A new 12 ga Romex feed has been run from the breaker panel up the left side under the cabinetry. It is awaiting the line set to be routed into the unit.

How or where is the drain line ?
Im still looking for a good inside front mounting spot . right behind the pas seat, just under the window is gaining votes.
The rear can go over the bed with the cables running through the bodywork to the front compressor . I hope to have 2 side by side compressors in the grille..

Re: Mini split A/C system

Reply #22 – September 07, 2021, 04:52:57 pm

PIONEER 9000 BTU 20 SEER Mini Split A/C Heat Pump 115V 16Ft Full Install Kit...
7 amps or so 1200 watts?

Rough math says seer 20 at 9000 BTU should be 450 watts?? Is that correct?

Re: Mini split A/C system

Reply #23 – September 08, 2021, 12:02:25 am

Okay, it is in and working, but what a pain to install. Getting the lines in was a bear. It is so quiet it is stupid, something like 35 decibels, kind of hard to measure as outside traffic noise, cicadas, and the neighbor's window AC are all audible. In standard setting it was pulling just under 1000 watts, in eco mode it dropped to just under 600. Outside temp about 89 degrees, inside set to 72. The outside unit is just noticeable from the inside, and lost in the local noise outside.

I routed the refrigerant lines forward through the bottom of the overhead cabinet and enclosed them in the standard cover sold with the mini-split. I then routed them down the wall next to the passenger seat, also in the standard covers, then under the platform and down through the floor to the outside unit. The drain line I simply routed to a 1/2" plastic pipe down the inside wall next to to the door, through the floor, and then past the propane tank to drain under the coach. The big problem was getting the lines to bend into place. I kind of started in the middle by the passenger seat ran back through the cabinet, then worked the other end down under the platform and out. I really needed to be thinner and have longer arms. I vacuumed it down last night and left it evacuated for about 18 hours, the gage never moved so apparently no leaks.

I am not sure if it has enough capacity to handle really hot weather, but I guess I still have the rooftop units if I need them. I did try running it off the 2000 watt Xantrex inverter even though I only have two 8D AGMs for coach batteries. It ran no problem and indicated about 2 hour and 50 minute run time available. I am going to put a Kill A Watt meter on it tomorrow and see how it does over the next few days when we will be up over 90 again.

Re: Mini split A/C system

Reply #24 – September 08, 2021, 08:20:27 am

This is amazing and well done.

Affiliate Notice