Mini-split AC

[kaypsmith]

Thought I would share my latest mod to the coach. When I purchased the bus back in 2009, the bus air did not work and that was no big deal because I have a generator large enough to run two roof units which are pretty comfortable except while traveling in 95+ degree daylight. So last winter I started a project of adding a mini-split unit to the coach. I first finally removed the old condenser unit, just behind the drivers seat and underneath the bus, this gave plenty room for the new condenser. I went with a 12,000 btu unit which uses inverter technology and is super quiet, a real energy sipper. I installed the inside evaporator inside (of course) above the window just behind the driver seat, this puts the air directly on my wife who sits in the co-pilot seat, and the biggest complainer about being too warm while traveling. I designed the unit to be run without the rear air on, but with the front rooftop running at the same time. Well to my surprise and with a couple of trips behind us in some very hot days, so far we have not needed to run the roof air while traveling at all, and the coach is staying very comfortable without either roof units so far this year. And one other point, the drain is just behind the left front tire, leaving no drain from the roof when the rooftops are not running.

[richard5933]

Nice neat installation. Any problems with the condensing unit starving for air when you're on the road? I only ask because I've seen others go through great lengths to add ducting and baffles to direct air to it, but yours seems to be making use of the vented bay door. If that's the old a/c bay, there should be plenty of air flow, since I assume the floor of the bay is open as well.

[kaypsmith]

No problem with venting, it is the old AC bay, the entire door is stainless steel mesh just like when it was new, the old 24 volt fan pulled air through the condenser coil which was mounted on the door, then blew downwards on the pavement below. The fan was an 18 inch standard fan. I mounted the unit 9 inches from the back wall allowing the new unit to be able to pull through that hole in the floor as well as having at least 10 inches clearance on either side if the unit and another 9 inches clearance across the top. The condenser fan blows the hot air far enough past the coach to keep the hot air from being inhaled back through the unit. Notice the white PVC pipe to the left of the condenser, that is the evaporator drain, I used a 3/4" hose bibb style fitting directly below the floor of the bay, allowing me to attach a regular water hose while parked to carry the drain-off almost anywhere downhill away from the campsite. If you recall, there was a post awhile back trying to figure a way to take the run-off away, that's where I got the idea to make use of this idea, LOL. I wanted to use mini-splits when I first converted, but no vender would sell me the units back then for fear that there may be leaks because of vibration going down the road. I used flare seals to help prevent this from happening, and there have several others that used this system and have logged upwards of 50K on at least two of those. So here I am, another guinea pig, and as I stated in the first post, I wanted to test some before announcing this project. Also as stated this unit is an energy sipper, startup draws 6.9 amps, with the unit blowing maximum in 94% outside, 4.2 amps, and at idle in early morning, outside temp 79%, just under 1 amp. With inverter technology, the condenser never turns off, it simply slows down, then as the thermostat calls for more cooling, the unit speeds up at a slow pace all the way to wide open which in turn stops the need for pulling a large load starting the unit at any given moment, by the way, I still use an old modified wave inverter 3K, and it runs fine on that, meaning I can actually cool while driving without running the generator. One other note, I was prepared to add a baffle/diverter on the mesh door to divert air flow, but the mesh is already designed for that purpose and with test results already in, I don't believe that will become necessary.

[richard5933]

Sounds good. Glad to see another solution out there for people that don't want the bumps on the roof. Could you share the make/model of the unit you're running?

[kaypsmith]

13 hours ago, richard5933 said:

Could you share the make/model of the unit you're running?

The branded name is Premium, the condenser is actually Toshiba, a trusted name in the mini-split market. I ordered off of ebay for $489.00 with free shipping, when I ordered 15 foot supply lines which worked great, the condenser is pre charged and was slightly overfilled. I did the uninstall of the old system and the installation of the new. I did call a local hvac dealer and paid them $150.00 to come out to evacuate the evaporator and lines and release the refrigerant from the condenser and levelized the refrigerant. The unit is also a heatpump which works very well here in the south because it does heat very well if outside temp is 40% or more.

[dennis@portofwinlock.com]

Has anyone ever put the condensor on the roof?

 

[somewhereinusa]

On 4/21/2022 at 8:31 PM, dennis@portofwinlock.com said:

Has anyone ever put the condensor on the roof?

 

I've seen them mounted high, I believe there is a problem if they are too high above the evaporator. The condenser does need to stand up that would put the top quite high.

[paul65k]

Very nice

On 4/21/2022 at 5:31 PM, dennis@portofwinlock.com said:

Has anyone ever put the condenser on the roof?

 

 

The condenser units must be placed vertically unfortunately :

Edited May 27, 2022 by paul65k

[paul65k]

We are still in the planning stages of adding a multizone (2 zones) to our 36' DP. I already have the220V circuit in place after extensive electrical mods that will allow us to run off-grid..... now I just need to figure out the mechanical part of actually fitting it in one of the storage bays

Thanks for posting this