Has anyone replaced their rooftop air conditioners with a mini split A/C system ?
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
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 .
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.
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.
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.
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.
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.
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 .
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 .
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.
Installed a couple by ourselves,if you have access to a leak detector it helps after the install.
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
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
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 .
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 (http://www.foreforums.com/index.php?action=media;sa=album;in=599)
In case your wondering, the coach currently is stilling up on stands in the suspension for access.
This looks awesome!
Do you have to take the dash AC out?
Please keep updating your project.
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.
Would like to see how the "rear" unit is mounted and keeping the water out of the belly of the beast (bulkhead)
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.
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.
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..
PIONEER 9000 BTU 20 SEER Mini Split A/C Heat Pump 115V 16Ft Full Install Kit... (https://www.ebay.com/itm/303597901411?mkevt=1&mkpid=0&emsid=e11051.m43.l1123&mkcid=7&ch=osgood&euid=7b21e857ebb14ba5902603c67be53589&bu=43119746964&osub=-1~1&crd=20210907132751&segname=11051&sojTags=ch%3Dch%2Cbu%3Dbu%2Cosub%3Dosub%2Ccrd%3Dcrd%2Csegname%3Dsegname%2Cchnl%3Dmkcid)
7 amps or so 1200 watts?
Rough math says seer 20 at 9000 BTU should be 450 watts?? Is that correct?
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.
This is amazing and well done.
That's a pretty optimal placement of the head unit. Yeah, the line installation sure must have been a real cherry. Will be looking forward to real life performance reports, those units typically produce way above their ratings, or old style AC is rated far optimistic.
I've put probably a dozen of these units in family property. My experience with Pioneer...better than MrCool, quieter and more durable and when I've needed parts Pioneer was easy to work with. Not to mention for the difference in cost you can buy a vac pump, flaring tools etc and have em for the future. Nice job!
I think that these newer units are pre charged .
Still have to evacuate the linesets and evaporator on most of them. Gas is precharged in condensing unit.
The DIY series from Mr. Cool have sealing quick disconnects on the line connections and have the lines pre-charged so there is no evacuation required. One of our former members used this to allow a temporary mini-split install that could be disassembled for travel. Of course now I can't seem to locate the thread.
Right . My MR cool has dry breaks . The Pioneer does not . Good point. Thanks,MM
I like over the door.
Maybe I can drop the cables straight down the wall and to the nose , through Top surface of the side boxes ?
I still have to remove the safe for room in the fender.
The nose will get the bedroom unit
Do you think that the cables can exit the handler box straight out of the left end of the case?
There is a knockout on the both sides, the manual says: Left hand side recommended for side exit. Left rear (though the wall) most recommended but less common. Right rear less recommended but most common. Right hand side not recommended unless absolutely needed. I ran the lines out the left side right into the cabinet. (Yes, there was some major pucker factor cutting holes in the woodwork.)
The install manual is available online as a download.
I didn't run the drain line with the refrigerant lines because it was slightly uphill into the inside of the cabinet.
I am really surprised some creative HVAC tech or manufacturer hasn't played mix and match with mini-split and RV AC parts to create a rooftop mount that matches the capabilities of a mini-split. It could be all one unit, but you put in the inverter drive compressor and super quiet fans I am sure it would find a market.
Ive looked at that .
Some engineering issues; tipping the condenser/compressor unit. The limit would concern the oil travels.
Configuring how to drain the inside air handler. It would have to be mounted above the roof surface .
The solution may be to use part of the OE handler ,and piggy back the compressor bits to feed it.
Marry the OE inside to the new outside stuff . Should be doable as the OE units are rated 13000 or more btu and should handle the loading . Still would contend with noise.
Frankenstien the new blower into the handler also.?
edit; the Minis are quiet because the blower motor runs slow and blows across the entire coil . The fan blade itself is pretty long. In order to pas the BTU the smaller coil needs a higher velocity air flow and thus more noise and amps.
Have y'all thought about removing the compressor from your rooftop and relocating it into the engine bay. Since most of you seem to want to run your roof AC's driving down the road splice in the compressor that's engine driven so you can use your rooftop units . once at your campsite close the solenoid valve and run them off electricity.
2 different refrigerants entirely incompatible. The top unit has to have the compressor that came from the factory to work.
Since your not using dash ac change refrigerants
I thought you were trying to reduce the compressor noise and use your rooftop units rolling down the road over and out
Mostly I just want a quiet and efficient AC system that might run off of the inverter.
Exactly. There are 30+ SEER mini splits available... That's 30 BTU per watt, probably four times more efficient than the standard rooftop unit.
I should've read the whole post first sorry for the railing🎈
https://www.homedepot.com/p/Pioneer-12-000-BTU-1-Ton-19-SEER-Ductless-Mini-Split-Air-Conditioner-Heat-Pump-Variable-Speed-DC-Inverter-System-110-120V-WYS012AMFI19RL-16/311474980 700$
The 12kand 9K units share about the same footprint and it appears that the watts only go up about 150 from the 9 to the 12 . based on the my prior experience, the 9K will almost cool the entire small 36 ft bus while the 12K should easily cover it. IT may need a small fan to cool the bedroom but we use a fan for the noise and air as it is ..
Looking like this one will fit and draw 1080 watts. There are a couple with the same specs but this one is cheaper and heavier by a few #s . Not sure why there are more than one in the same game from the same manufacturer. This is maybe the older design and only SEER 19 .
I am very close to the 16 ft line requirement when mounted above the door. Run the cables/drain into the first cabinet anddown next to the window( behind the drapes) into the storage boxes. The drain exits the box and the lines continue along the box ceiling to the wheel well mounted compressor unit. Right where the safe is now mounted MOL.
Be sure and allow an additional amount for each bend, they eat up more than you might think. There are also available flexible lines which you could add for a couple more feet and probably not a bad idea for vibration mitigation at connection to condenser. I've had two failures with Pioneer, both 9K units, but 18K have been rock solid. In fairness these were mounted in direct salt air blast off the beach but still it seems the larger units are more durable.
I originally ordered the 16' lines and then realized they were too short. I then got the 25' set, and ended up shortening them about 16" to about 23' 6".
Performance wise, currently it is 89 degrees outside here in KCMO, but to simulate hotter weather I have the thermostat set for 62 degrees. That should be similar to a 77 degree setting on a 104 degree day. The thermometers are reporting 63 at the dash and 68 in the bedroom. It feels like a meat locker. How would it do in the desert sun? That remains to be seen.
I am going to run it at 62 until midnight so I can capture a full 24 hours of use to find the average load. So far it is has used 6.14 Kilowatt hours in 16 hours and 51 minutes, or an average of about 364 watts per hour. The coach is now mostly shaded, but was in the sun until about 2:00 PM. It was only about 74 out at 6 AM, so it wouldn't have been working very hard then.
The Pioneer website shows the inside 12000 BTU unit as 31.57" wide, so it wouldn't fit where I put mine, that is why I went with the 9000 unit.
Okay, it finished its 24 hour run. The mini-split used a total of 8930 watthours in 24 hours, or an average of 372 watts per hour. I am not sure how meaningful the number is, the coach was sitting mostly shaded, nobody was in it, no regular life style heat sources such as refrigerators, toasters, coffee makers or anything adding heat to the mix. I wish the Kill O Watt meter could handle the roof units so I would have a point of comparison. Anyway, there it is.
Mike, You scared me a little but I was sure that I measured a few times for fit. I have 34.5 in space over the door between the cabinets.
AC rough math. The 400 or under watts will easily run from the 2000W inverter . As well as from the engine alternator . Drawing about40- 60 amps on cruise and maybe 100 at full on cold. The Eco mode should stay well within alternator range IMHO . This is about 1/3 the draw of the overheads ,MOL and they will not run from the alternator very long. ,or at all.
In my case I added a GM one wire 100 amp wired directly to the house bats -- because I dont know how the Duvac works on my bus as well as I like added redundancy .
Edit, more rough math.. If the overheads are using 1400 wats and output 14000BTU. Thats an honest SEER 10. The BTU output is suspect IMHO .
The Minisp[lits are using 350 - 600 watts and output 9000 - 12000. Real SEER around 17 or a little more . Its clear that the mini 9000BTU are large BTU..
Replace the overheads with solar and maybe even use the wires from the AC.
Well, I just did a bit more testing, running the mini-split off the inverter. Ran 4 hours, set at 74 degrees, outside temp was 91 when I started, 89 when I finished. The Kill O Watt reports 1.97 Kwh used, the Xantrex battery monitor reports 197.7 Amp Hours used (12 volt system). 51.1 % charge remaining on my pair of O'Reillys 8D AGMs. I did find online that the Kill O Watt meters tend to over state use on some loads.
This is working so well I am kind of thinking of taking off the old roof top units, at least the front one. That would free up more than the area of the unit itself as I was also not going to use the shaded area for solar as well. I could probably fit two more 250 watt solar panels. I have 7 waiting to go on, just haven't gotten around to it.
I just ran the monthly engine exercise, idle until air pressure comes up, then 15 minutes at 1200 rpm, then 2 minutes at idle again. The batteries were still down so it was a chance to see what the charging system could do. I was seeing 60-85 amps going into the batteries even while still running the mini-split. My coach has had the OE alternator replaced with a 160 Amp Delco unit.
Has anyone considered a mini-split, using a ceiling mounted evaporator, in place of the roof mounted AC unit?
Tim
I have been wondering if we are looking at this wrong. Maybe one of the concealed ceiling units in place of one of the propane furnaces, or maybe under the refrigerator? I kept looking at the ceiling cassette type, but they are 22.5" square and too thick for an RV ceiling, but I forgot the concealed units.
yes
Looked at this. You have to run the lines down through the wall to the compressor unit.
The concealed wall would work in place of the front heater but that dumps at the floor.
I was thinking about running the lines through the engine room and roof, for the rear unit, and through the refrigerator compartment and roof, for the front unit.
Tim
An adapter to manage the 22.5 inch opening and the ceiling dimension?
Tim
Adapter / sawzall
Engineering wise , the air handler has to drain the water. The overhead placement of the unit still needs some thought to that end .
The inside ductless air handler drains by gravity . Make sure that the drain pan has enough slope when driving or parked to continue draining . It may require a slight tip to the drain end to drain under all conditions. IMHO.
Have you noticed any condensation along the line bundle? I dont see any on my home unit outside ,but these I hope to run into the cabinet and down behind the pas seat.
Hows it working out so far? Thanks.
Mine comes in tomorrow and I hope to have it running next week . I found all of my AC tools and sourced the adapter for vacuuming it down.
I have seen no condensation inside the coach, only outside at the fittings on the outside unit. I don't think there will be a problem with the inside lines since the humidity inside the coach is lowered by the mini-split itself and the lines are fully insulated.
The mini-split just plain works. I used it in heat mode the other day on a cool morning and that worked great as well. It has worked so well I actually went ahead and removed the front rooftop A/C and capped off the hole. I also removed the air horns to open up more space for the solar panels. The horns will be relocated behind the grill. I haven't filled in the hole in the ceiling from the A/C on the inside yet, I am kind of still working that out. That can wait for bad weather, right now I need to work on the outside.
My solar panels are kind of odd balls. They are used 250 watt 72 cell units, 31.4" x 61.3". The plan is 3 across in 2 rows over the front of the coach, and one more over the bedroom. That leaves the roof pretty clear behind the kitchen roof vent with access to the both vents, the skylight, and the rear A/C and enough room for more solar in the future if needed. The refrigerator vent is going away, I have a residential refrigerator waiting to go in.
Started on my install today.
Notes; get the 25 ft line set. Pioneer will credit my 16 ft set . Great customer service so far.:)
The safe is glued in really well and the front edge of the seat covers the flange . Remove the seat, and seat base front bolts. Pry the flange edges after removing the carpet strip surround. I floor jacked it up and shoehorned the carpet away. Paint the exposed plywood edge, reinstall the carper strips and safe cover. I will seal the cover and the edges under the floor.
The outside compressor unit is larger than the spec sheet says . Overall length on this 1200BTU unit is 35in to the end of the line junction cover . FWIW the box for the inside unit is almost the perfect model for the outside unit .
This fits where the safe was and fills that area pretty well. I built a bracket that welds to the jack frame and the front body support . The AC box will bolt to a pair of slider mounts that bolt to the fixed brackets. If I get the measurements correct, the unit will come out with the tire removed .
The inside unit fits well over the door. About 4 in below the corner of the ceiling is a metal tube to screw the mounting bracket to.
I tipped the inside unit about 1/4 in towards the drain end. The bus is not always level ..
I drilled a 2-1/8 in hole for the lines through the end of the cabinet. Just like Mike's path. I have the curtains and ran the drop behind the curtains to the seat area.
Update; Fired it up today . Icey cool. I have to look at it to verify that it is running m cuz the little temp light is on. Silent .
The outside unit fits under the pas wheel house/ pas seat with the safe removed . I welded a fixed bracket to the frame to support the front /line /cord , end . The rear tire side support bracket bolts to a weldment that is welded to the HWH frame drop.
The mounting brackets are all angle iron . 2 rails bolt to the unit. These rails bolt to the frame brackets. Easy to move , mounted on it own rails along the brackets .
Get the bus up on 3 sets of 2/12 blocks and turn the wheel to the right . Bench press the unit up and over the front frame, support the rear while you bolt up the support . Slide it back and wire the lines and plumb the coolant lines.
Turn the unit so that the air flow has the easiest exit out of the fender opening .
I have not measured the watts draw yet as I sent my killa watt to somebody. Ordered a new one along with a 2500watt Pure sign wave inverter . Same brand as my 3 yr old 1000 watt unit .
I still have to prettify it yet and clean up the inside line look.
Notes, 36 ft with no slides , the 9000BTU unit should be fine and use less power.
Also make sure to get a unit with the ECO mode***. Mine was supposed to have this but seems to not . So the watts will stay around 800 - 1000? maybe . Pics on request .
The ECO mode button is under the sliding cover on the remote. The bottom part of the remote slides down.
Just found the other instruction book and right on .. When in doubt . I blame it on the Stupid phone .
Has anyone made close outs for the roof AC units? I plan on making some foam and fiblreglass plugs.
Edit ;; The amps are low enough that it will run fine with my 100ft 12 wire cord that is my normal storage plug. I wont need the 50 amp extension cord . Just the 50 to 15 pigtail adapter .
Also,,, I was adding a couple pieces of plastic sheet for air control. I turned the unit off and went to work under the bus. The condenser fan came on high speed . But I noticed that the airflow was reversed . The fan run backwards to blow crap out of the coils at certain times. High tech .
Pic
I used the OE valence tipped on end to cover the line set.
Cut to size, and stuff the ends against the floor and the cabinet . A single screw retains the upper square wood strip . Staples
retain the valence with 1/4 in air line keeping the edge taught. I dont hate it .
The drain line will go straightish down to the floor . FWIW the steel frame runs inside of the walls by about 1.5 in +_. That wont allow the drain line to run straight down the door jam and exit through the floor . It has to run about 1.5 in inside of the wall . So I will use the bendy drain line and clamp the hose as neat as I can .
Harbor Freight now carries the Kill O Watt . BTW. 26$
Edit update
Eco amps average about 7
Run amps about 7.9
840 to 1000!watts
Latest ; Change the door knob..
I ran the line set through the cabinets and down behind the Pas seat . Good chance to get rid of the OE drapes and valence. Ordered cordless shades. Nice. makes the room bigger . First set was faulty. New set OTW. . In progress.
Also now the fluorescent tubes are exposed ..
Removed the roof top AC units . Made up a filler and will insulate with foam and some sort of interior finish . In progress.
Drilled the drain hole in the floor at the door. Good time to remove the OE carpet and finish with some extra bathroom vinyl tile . In progress.
Also a good time to stiffen up the lower door hinge area. In progress.
The low amp draw of the Mini split lets me think that I can run it off of the extra 100 amp Alternator , with a new BA inverter . Installed new 2500watt inverter . Ran today at 11 amp total . That means that I need at least 150 extra amp alternator as well as some large cable . In progress.
Simple things in pieces . One piece at a time .
Pic
The wheel well has a fixed rock guard and a flexi guard. The flexi guard is what you see in the pic .
The into is turned so that air enters and exits as easy as space permits.
Edit. I found the missing cover screw. Now I can relax .
Todays note ; 8 amps - 850 watts or so . silent AC.
Changing to a to a mini-split or mini-splits is on my list, it is at least one year down, lots other things to do, like solar.
Mine still works well.
Ordered 2 more for my house.