Read through many mini-split posts but did not read much about those who had to do at least some freon charging and some tubing flaring and such.
Trying to decide which way to go. The MRCOOL DIY kits come fully charged and tubing dressed and ready to connect, cost is higher naturally than other brands where compressor is recharged but line is not so install required vacuum and some freon charging.
Not having proper tools nor previous AC install experience, on the fence about paying up for MRCOOL DIY kit. Several hundred dollar premium making me mull it over.
I've been thinking about building a system from scratch too.
I was thinking about moving the stock condenser to the roof, using several evaporators and fans with individual control where needed.
AC Vacuum pumps are cheap. I have one for other work. What I don't have are the gauges or the know how.
They make condensing units specifically for bus rooftops, usually on city buses. Perhaps you can use that as a starting point as you design things.
I did make my own lines for one of the two I installed. Nothing really difficult but, I have automotive AC experience. You need gauges for 134 and an accurate scale plus the freon. A digital postal scale is much cheaper than the ones marketed for freon.
How do you know how much freon to put in a DIY system ?
Does the condenser need to be upright ?
How do you know how efficient your system will be ? Mini splits are engineered for high efficiency. (high SEER)
Quote from: richard5933 on August 28, 2020, 05:37:03 PM
They make condensing units specifically for bus rooftops, usually on city buses.
Thanks for sharing that. I had no idea.
These forums need a "Like" button.
Do a Google search for "rooftop bus a/c" and you'll see lots of options, from many of the companies you've heard from already like Eberspaecher and Red Dot. Some use engine compressors, some seem to be electric only.
Lots of these are used in things like mobile command centers, mobile libraries, etc. as well.
If you are going to put the condenser back on the roof...
Why not just put a traditional RV roof AC or heat pump?
The point is to get your height down...?
Good Grief, Charlie Brown...?
Round and round...
Why does my head hurt?
Happy coaching!
Buswarrior
Nothing ventured nothing gained. You can make a vacuum pump from an old fridge compressor. A set of gauges and scales not too expensive. You could probably calculate volume for hoses etc and calculate capacity but could also fill the system and watch the gauges to get you in the ball park without a scale If there's a site glass on the drier you can watch for bubbles which is an indication of low charge. Also need to learn how to solder copper.
Once I was too poor to buy a marine AC for a boat so I took a window unit and cut off the condenser and mounted it in a tank .
The tank was mounted under sink in the head. Ran copper lines from it to AC and installed a livewell pump to constantly exchange water in tank. Worked great.
Time to purchase the coach, then get back to us.
Quote from: buswarrior on August 28, 2020, 07:17:52 PM
If you are going to put the condenser back on the roof...
Why not just put a traditional RV roof AC or heat pump?
Because they are crap quality and poor efficiency. And I don't want an AC poking through the ceiling in my coach. You got a problem with that ?
QuoteThe point is to get your height down...?
Who says I have a height problem ? You might be concerned about height, I am not. Did I mention anything about height ?
Why don't you worry about your coach and I'll worry about mine.
I bought a Pioneer 12K inverter minisplit with heat pump that will be a mostly-DIY installation, but I will have a professional A/C tech do what I cannot, such as pulling a vacuum in the lines for 24 hours to check for leaks. My outdoor unit is precharged with refrigerant, but the lines still need to be evacuated; they are however already dried and sealed against any further moisture getting inside before they're installed. I deliberately chose a system that doesn't have precharged lines, specifically so I could check for leaks before opening the valves to let the refrigerant into the lines.
Whether the Pioneer is any better than any other comparable brand is of little concern to me - all minisplits are of comparable overall quality and are a mature technology by now, and any warranty will be negated anyway if it's known that it's in a vehicle, so I chose one that's not too pricy but not suspiciously cheap either, and one that plenty of RVers and mobile users are having good success with. Yes, I could have bought something different with a higher SEER, but that's not my main concern with 2kW of solar on the roof!
John
John,
Must not have written the OP clearly but you are spot on with my dilemma. The MRCOOL DIY kit has lines and compressor precharged so no need for gauges, bulk freon, flaring tools, etc. The Pioneer type kits do not have precharged lines and that steps takes the tools and skills to DIY or hire that out.
The MRCOOL DIY kits are premium priced for eliminating having the installer to do any AC specific work, just hook up and route tubing. I'm leaning toward the MRCOOL option as there is value but just not sure if totally worth the higher product price. Going to Youtube a few installs with the Pioneer type kit then decide.
BW - I'm very clear nothing involved with AC is going on the roof. I may be nuts but not crazy. lol
You mean crazy like Marathon?
Update.
Originally landed on MRCOOL products and DIY 120v 12k BTU unit. This kit is the easiest to install and requires no special tools, equipment, knowledge, or skill.
More research ran me in circles, all the while, gaining more knowledge about this specialty field.
Finally, came back around to MRCOOL as it is a solid and very popular product. Rather than the DIY models, I chose the Advantage series. Order is placed via Lowe's.
MRCOOL Advantage 3rd Gen 12,000 BTU 1 Ton
Ductless Mini Split Air Conditioner and Heat Pump- 115V/60Hz 19 SEER
Item #2538961Model #A-12-HP-115B
Quick analysis.
The Advantage is far less costly than the DIY series but the performance is slightly less on paper but still very respectable capability. The added steps are quite manageable. Initially, working with the pressure fittings and such seemed a bit daunting but after a video or two, it was a cakewalk. We all here have the requisite experience as it is the same stuff we do servicing AC in our cars and the brake and steering systems - nearly same stuff.
Purchased using credit card and from Lowe's, both offering the best protections for handling all transactional and product issues.
The runner up was Pioneer, good pricing and decent reviews and same type of kit as the Advantage but buying a solid brand from big box were the determining factor.
Seems pretty straight forward. Watched a video of one being installed in a home in the upper peninsula and seem to hold it's own during the winter climate there.
I am happy with my roof tops if I was building a bus today it would have roof tops,since Cruise Air are no longer made like I used on my Eagle,2 units were mounted in the spare tire compartment and 1 was were the battery was remove and moved 21 years later they are stilling working says Matt plus you could adjust the fans to any speed no 3 speed,I had the units installed in Seabrook Tx by a marine dealer best choice I ever made
We have both, a Coleman Mach 15 roof top and a Pioneer 12,000 Mini Split.
The first installed was the Mini split, was a bit of work, Worst part was running the copper lines.
The Condenser was installed in the Front driver's side bay, evaporator up over the windshield.
To aid in the installation I bought this gage from Pioneer: https://www.highseer.com/collections/accessories/products/mini-split-r410a-low-side-suction-charging-service-gauge-hose-set-5-16-port?variant=24482164211776 (https://www.highseer.com/collections/accessories/products/mini-split-r410a-low-side-suction-charging-service-gauge-hose-set-5-16-port?variant=24482164211776)
And this vacuum Pump from Amazon: https://www.amazon.com/ZENY-Single-Stage-Economy-Conditioner-Refrigerant/dp/B012CFTYX4/ref=sr_1_6?_encoding=UTF8&c=ts&dchild=1&keywords=Air+Conditioning+Vacuum+Pumps&qid=1598886415&sr=8-6&ts_id=15707041 (https://www.amazon.com/ZENY-Single-Stage-Economy-Conditioner-Refrigerant/dp/B012CFTYX4/ref=sr_1_6?_encoding=UTF8&c=ts&dchild=1&keywords=Air+Conditioning+Vacuum+Pumps&qid=1598886415&sr=8-6&ts_id=15707041)
Both worked well, the Pioneer Condenser unit comes precharged with R410A, after the install you vacuum down the lines, let sit for most of the day, if the Vacuum holds release the refrigerant.
This unit works awesome, given enough time will cool or heat the entire bus and it does it efficiently.
Problem comes when the temps start to get into the upper 90s, or when the Bus is hot and heat soaked, the mini Split will not cool the entire Bus quickly.
After much thought we decided to put in a second AC of the roof top variety, whereas the Mini Split is nice and efficient, Cools good and sips electricity, we went completely opposite with the roof top unit and went with the Biggest unit that would work on 110 volts with no thought on efficiency.
Just in case we decide to change up in the future, I did not want to randomly cut holes in the roof and mounted the rooftop unit in the rear escape hatch.
The Coleman Mach 15 15,000 BTU unit kicks @$#, between the 2 units, we can cool the bus from 110 degrees to 78 degrees in around 20 minutes.
We are quite happy with the result, often use Both to bring the temp down and then maintain with the Mini Split, on a hot Florida day we will turn the Coleman on to maintain the Icebox that the Wife likes.
Peter
Thanks for mentioning that. Rooftops are noisey but they cool down better, faster than the mini splits. Once their market share starts to degrade significantly, then the mfgrs may make the needed improvements. Problem is there are great peaks and valleys in the rv business. Hard to invest in innovation when a recession may be just around the corner.
Peter,
Thank you for the links and sharing your experience. I ordered the MRCOOL Advantage that comes recharged except for lines that need the same vacuum procedure as your Pioneer. With those tools available so cheap, I'll need to ponder whether to buy or stay with decision to get free loaner tools from Oreilly's. Not sure how often I'll use those tools on other projects in the future.
QuoteRooftops are noisey but they cool down better, faster than the mini splits
Are you comparing equal BTU output units? Certainly, more powerful mini-splits can outperform a 120vac rooftop which max out around 15k BTU while a 240vac mini-split can easily deliver 20k+ BTU.
As I just made this recent purchase, I'll share my rationale. Getting more than 15k BTU requires 240vac that required purchase of a new dc/ac inverter. OK, that is understandable but the total cost of a 18k - 24k mini and the inverter was pushing my pocketbook for this upgrade. A second consideration was something I read that mini-splits are or are line heat pumps and prefer to run more often than start/stop. If that is the case, even with mini on low setting, it was unclear how much it would run vs start/stop.
The last puzzle piece is future proofing. Depending on how the mini works in the salon, it may be fine as is or need more BTU at which time I plan to upgrade to 240vac mini for the salon and swap the existing mini with the rooftop in the bedroom. That should provide sufficient flexibility to make the thing an ice box if desired.
A related factor is gaining more real estate up top for more PV panels. Currently, there are six residential panels and room for two more. To add the next pair for a total of ten, the rear rooftop needs to go. If I decided to go to ten, then the bedroom rooftop goes and another mini goes in. Sizing of second mini depends on how things work out with the first mini in and proceed as described above.
Lastly, a couple other considerations. Why not just by a two zone mini-spilt now? Well, they cost quite a bit more and at present it remain unknown how well the one will work with the aid of the back rooftop. How much BTU for each zone is unclear. Also, they all run 240vac so there is added cost and effort installing two at once.
One mini-split now still allows for possibility of incremental upgrade later while deferring spending more $ up front and not installing too little or too much cooling. The path I've chosen provides the benefit of redundancy so there will always be coach cooling, although reduced BTU which are better than zero with a 2 zone unit.
Who knows how it will all actually work, it's all a big experiment and entertainment. :)
I had a 9 k split unit up front above the windshield and a 13.5 k roof shaker above the bed in the back of the M C I . most times the split unit would keep the coach cold but there was times when I had to turn on both units to super cool down the coach and then turn off the rear unit . because the split unit was so quiet it was used most of the time with a small floor fan to sent the cool air to the bed room . coach was spray foamed and I am sure that helped
https://photos.app.goo.gl/Et8FvK1BRX5Jpupk6
dave