Oversized indoor minisplits?

[Crisfole]

So I had been thinking this might be a doable idea, but hadn't seen this before, so I wasn't sure:

https://www.ecomfort.com/LG-L4H54W15...-A/p57734.html

That's a 54k BTU mini split with 69k BTU worth of indoor units. I don't want a 54k BTU mini split...5.5kW is too much. But I had been wondering if I could have oversized indoor units. My plan has been to zone the bus into thermally separated zones so that I could only cool the areas in use. (Probably using insulating curtains downstairs, and an insulated door upstairs).

Now, I know that the total output is limited by the the outdoor unit. But will a system like that actually work? Can I have a 36k BTU unit with 15+15+9+9 so I can use two zones at 15 sometimes, and then all 4 at 9 other times? Trying to work out how this would go...either it will spread the cooling evenly, giving me 9k in each zone when all are on full blast, _or_ the two oversized zones will consume everything leaving nothing for zones 3 and 4.

[cadillackid]

the way those work is that when you run them all the time nost likely a coupole zones will begin nearing their setpoints and the fans slow down, the EEV will regulate the freon flow accordingly so that unit doesnt freeze at lower air volume.. this allows more capacity for other zones.. these units arent just on and off..

now if all 4 zones are calling for max cooling, the system will provide as much as it can to each zone but will run the compressor at max which is an inefficient mode of operation but it womnt hurt it.. again once zones begin reaching requested service the system will limit flow to that zone which means others neediong more will get more.. do be sure that the outdoor unit is capable of taking 9s and 15s some of those indoor units have different fitting sizes.. or the outdoor unit fitting sizes only accept larger unit on may be 1 zone.. you need to read up on the system before you buy it.. and be sure you can run it.. a large system like that will need 220 volt mains..


-Christopher

[Crisfole]

At the moment my plan is a spendy system �� with a few 220 circuits. I am fully aware that comes with many extra challenges. That being said, I'm hiring out a bunch of the actual connecting things work, so I think it'll at least be safe. Especially since I plan on being there while the work is done so I can learn and fix things later. Having a professional do it makes my insurance company happier.

[Native]

Hire Cadillackid to design and install it!

[Crisfole]

Readily! Columbus to Syracuse is a 7 hour drive. @caddilackid, you in?

[cadillackid]

ha! going north in fall / winter isnt my thing unless its just for a quick visit.. my little body just plain doesnt do working outside in cold..



have you figured out where ypou will put such a massive outdoor unit?



what are your plans for the 220 volt power to run that.. are you planning on being at campgrounds that provide 220 volt power? many dont like loud generators overnight.. and batteries are pretty prohibitive to run a system like that for very long..

-Christopher

[Crisfole]

Yeah, planning on a rear shelf between up and downstairs windows. The unit I'm actually looking at is a 36k BTU LG and is 13" deep, and 37"x32". With 8'2" across the back that leaves the other half for a generator.

As for power, I've run the numbers and think I pull off a large enough split phase inverter, battery bank and solar setup and still stay under budget. The goal is to use the zones to limit usage at any given time and to keep the bank large enough that we leave the generator off until morning. Conveniently the temperature differential goes down a lot at night most places.

[cadillackid]

remember there are minimum clearances required for proper airflow around a mini split.. and you have to be able to bend and route the copper piping without kinking it.. those condensers dont like heat.. so make sure a generator next to it isnt belching engine heat from its cooling fans onto the coils of the minisplit..



read the online installation manual for you unit to getthe required clearances before you order it


-Christopher

[Jolly Roger bus 223]

i have had instances where i have gotten letters from lg and mitsubishi to keep the front clearance off the wall at 3 inches and stack units to twin together.
have also gotten permission for back to back units to the same 2 foot spacing requirement for each unit.
havent done to many many lennox or pioneer systems but the few i have done are cheaper than the big name brands and so far just as good.
i say that with experience and any brand of unit problems is usually an installer didnt do it correctly? for any brand mini split indoor its is always getting rid of the condensate? there are pumps that fit under there cover but its just one more thing to clean and maintain and you wont know its a problem until its a problem? mini split indoor units have to drain from there condesate hose whether by gravity or buy pump to a gravity drain.

[Crisfole]

OK. I'm feeling pretty good about this. Assumptions in red ready for correction:

https://www.ecomfort.com/LG-L4L30W09090912/p79005.html

It's a 30k BTU A/C and Heat Pump "Reliable to Extreme Degrees" (LGRED) (heats down to -13 which I truly hope I never experience in the bus). The below is summarized from the service manual (located here), and the installation manual (found here; specifically portions relevant to the LMU300HHV).

Stats:

Voltage: 220V
Weight: 152.1 pounds
Dimensions: 37-13/32" x 32-27/32" x 13"

Below data is Listed as Min / Rated / Max

Cooling

Capacity (BTU): 8,400 / 28,400 / 34,080
Draw (kW): 0.94 / 2.27 / 3.47

Heating Stats:

Capacity (BTU): 10248 / 28600 / 41600
Draw (kW): 1.29 / 2.32 / 3.55

Installation:

For my case (flat against back wall of bus with infinite space on all side but behind and on one side of my choice) it looks like I need minimum 4" offset from the back of the unit to the rear of the bus. More is better for capacity, but worse for required platform strength.

Power:

I intend to build an large battery bank and solar array. I feel like I have to say this everytime I mention this; but I know it's going to be either complex or expensive. I will also have a backup generator to re-charge and back-up the battery bank.

[musigenesis]

There's nothing here in red. When you make an assumption, you make an ass out of u and mption.

[Crisfole]

Yeah, I totally changed my post between writing that and actually clicking post; found the right manuals. Now the only assumption is the implicit one from the OP: I assume I can have 4 15k BTU internal units and if I manage my zone usage it will not damage the unit.

Poor mption, it never did anything to earn its reputation.