Mini-Split A/C install question?

[PNW_Steve]

Hey Everyone,

As I watch the last of the snow melt I am contemplating the obvious... Air conditioning.

I am seriously considering installing 2 x 12k Btu mini-split's:

https://sharkaire.com/epages/fd93bb6...f7/Products/12

The units come with copper lines that, as best I understand, are not the best choice for mobile installation.

I wonder if it is practical to replace those lines with an automotive type of refrigerant line?

If so, what type of line & fittings?

Any special steps or precautions I need to consider?

Any other thoughts?

Thanks.

S.

[WanderWoman]

These are exactly what I am planning on installing, so I'm looking forward to the responses you get.
Sandi
www.thismidwifetravels.com
Living full-time on my Skoolie.

[Njsurf73]

Originally Posted by PNW_Steve

Hey Everyone,

As I watch the last of the snow melt I am contemplating the obvious... Air conditioning.

I am seriously considering installing 2 x 12k Btu mini-split's:

https://sharkaire.com/epages/fd93bb6...f7/Products/12

The units come with copper lines that, as best I understand, are not the best choice for mobile installation.

I wonder if it is practical to replace those lines with an automotive type of refrigerant line?

If so, what type of line & fittings?

Any special steps or precautions I need to consider?

Any other thoughts?

Thanks.

S.

I don't know if you have looked and decided that 2 units are best, but they make double splits... One "outdoor" compressor and 2 indoor condensers. Less space taken up by 2 seperate units. As for the copper, I am interested to hear opinions on that as well.

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[PNW_Steve]

Originally Posted by WanderWoman

These are exactly what I am planning on installing, so I'm looking forward to the responses you get.
Sandi
www.thismidwifetravels.com
Living full-time on my Skoolie.

I would call this a bit on the "experimental" side. I have seen a few folks do it and I like what I see so far.

No "lumps" on the roof.

More control over where I place the air handlers

QUIET!

Much more energy efficient than roof air.

MUCH lower startup current draw than roof air. This means you can run them on a much smaller generator or inverter. It looks to me like, with some care, I can run two of them on a 3-4kw generator.

I plan on putting the outdoor units in the (modified) storage bays.

Grab some popcorn, sit back and watch

[PNW_Steve]

Originally Posted by Njsurf73

I don't know if you have looked and decided that 2 units are best, but they make double splits... One "outdoor" compressor and 2 indoor condensers. Less space taken up by 2 seperate units. As for the copper, I am interested to hear opinions on that as well.

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I have looked at the "Double 12k" units and the outdoor unit would not fit the available space as well and I like the idea of a bit of redundancy.

Good thought though.

Edit: I think the condenser is outside and the evaporators are inside. Do I have this right??

[Njsurf73]

Originally Posted by PNW_Steve

I have looked at the "Double 12k" units and the outdoor unit would not fit the available space as well and I like the idea of a bit of redundancy.

Good thought though.

Edit: I think the condenser is outside and the evaporators are inside. Do I have this right??

Probably. I am not an HVAC tech, by any stretch of the imagination lol

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[family wagon]

Originally Posted by PNW_Steve

I think the condenser is outside and the evaporators are inside. Do I have this right??

Yes that's right. I always have to pause and think it through... At the indoor unit, heat from the room causes liquid refrigerant to boil into gas. It evaporates. Likewise at the outdoor unit refrigerant gas is compressed which makes it very hot, and as it cools it forms dew drops inside the pipe.. condensate.. and turns to liquid again.

I know you're not quite in a big metro area so this may not be much help, but I'd expect an industrial hose supplier could make an R410A compatible hose to your spec. Here in Salt Lake I routinely have hydraulic, brake, air, and other hoses made at Evco House of House, which is a division of Lewis-Goetz, which also has a branch nearer to you in Kent, WA.

I say just go with the copper and upgrade it later if you have to. Use vibration-tolerant installation techniques, for example bend tube in a full circle plus another 90 degrees rather than making a 90 degree bend directly. Mount the tube so it's supported but remains free to move a little. Hopefully that'll minimize the risk of work hardening small areas leading to eventual cracking.

[somewhereinusa]

The units come with copper lines that, as best I understand, are not the best choice for mobile installation.

I wonder if it is practical to replace those lines with an automotive type of refrigerant line?

Mini splits use much higher pressures, I tried using the AC lines I took out, they soon developed leaks. I checked into rubber lines that would handle the pressure they are made of unobtainium and unaffordium. What I ended up doing was slitting the insulation on the original copper tubing, very carefully routing the copper then putting the insulation back on with silicone and tie wraps.
I was able to route inside of dash and around windshield. You do need about a foot behind the unit for a nice sweeping bend out the back. I also recommend that you add a second drain. These things make a LOT of water.

I think you will find that the Double 12k units are all 240V. When I was looking 12K was the biggest you could get that are 120V. I installed one in front and one in rear.

[miltruckman]

Its not a big deal, or hard. Search for "barrier ac hose" on eBay. Hose, fittings, and the crimping tools are there.

Bill

[somewhereinusa]

Originally Posted by miltruckman

Its not a big deal, or hard. Search for "barrier ac hose" on eBay. Hose, fittings, and the crimping tools are there.

Bill

Thanks, when I was looking 2 years ago I couldn't find anything like that. Maybe just didn't know how to ask.
If I have trouble with the copper, I'll go with that.

Dick

[Njsurf73]

Originally Posted by somewhereinusa

Mini splits use much higher pressures, I tried using the AC lines I took out, they soon developed leaks. I checked into rubber lines that would handle the pressure they are made of unobtainium and unaffordium. What I ended up doing was slitting the insulation on the original copper tubing, very carefully routing the copper then putting the insulation back on with silicone and tie wraps.
I was able to route inside of dash and around windshield. You do need about a foot behind the unit for a nice sweeping bend out the back. I also recommend that you add a second drain. These things make a LOT of water.

I think you will find that the Double 12k units are all 240V. When I was looking 12K was the biggest you could get that are 120V. I installed one in front and one in rear.

I hadn't thought about the 240v. Yeah I am starting to think 2 units are the way to go. If your on 30 amp, you can still run one.

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[EastCoastCB]

Originally Posted by Njsurf73

I hadn't thought about the 240v. Yeah I am starting to think 2 units are the way to go. If your on 30 amp, you can still run one.

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I know most of the mini's I've looked at only need around 7-8 amps. IIRC they need about half what roof units need.

[Njsurf73]

Originally Posted by EastCoastCB

I know most of the mini's I've looked at only need around 7-8 amps. IIRC they need about half what roof units need.

That would be awesome. Be able to run them both even on 30a service!
Well now I just need a converted bus and a couple of grand! Lol

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[EastCoastCB]

I just looked at a couple 12k's online and they were both 15 amp. The 9k's were 8 and 9 amps.

[Njsurf73]

Originally Posted by EastCoastCB

I just looked at a couple 12k's online and they were both 15 amp. The 9k's were 8 and 9 amps.

I think 2 9k units would be fine. That is purely a guess and has no basis in fact lol

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[EastCoastCB]

Originally Posted by Njsurf73

I think 2 9k units would be fine. That is purely a guess and has no basis in fact lol

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If you insulate decently, I'd say they'd work well. a 9k is rated for 300 sq feet. Two of them should have no trouble. I'll only be running one 9k mini split and a 5k or 6k window unit in the rear. And I'm in FL.

[Njsurf73]

Originally Posted by EastCoastCB

If you insulate decently, I'd say they'd work well. a 9k is rated for 300 sq feet. Two of them should have no trouble. I'll only be running one 9k mini split and a 5k or 6k window unit in the rear. And I'm in FL.

That sounds like a decent setup.
I saw someone on here mount a window unit in the basement and duct it like a central a/c. Lost the thread, but was wondering how it turned out. He put a helper fan in the trunk to push the cold air through.

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[PNW_Steve]

I have run across a couple of folks that tested and published current draw numbers. At the moment all I could find is a quote from the Busconversions.com forum:

"Didn't tell whole reason for making choice; Started separate thread as not to take away from performance test. The inverter technology does not have the start up surge of the roof tops. The 12000 BTU 9 amp is constant. These are heat pump units the vary speed of fans and compressor as to demand of your thermostat. 9 amps is max. Hard to get used to when you first start them you think they are broken.They start slow and ramp up slowly to speed-both fan and compressor. Max inside decibel on the 12000 is around 40. much quieter than the roof tops that are not ducted. When you temp setting is reached the units decrease the fan &compressor speed to almost quiet until needed again then ramp up as needed. I haven't noticed then over 1/2 speed once temp has been reached. Point being when at a 30 amp service with roof air was challenged to do more than run one plus everything else. Roof air pulling up to 20 amp on start up and 14 running. Two mini-split (12000&9000)running= max 16 amp running and no surge. Thru testing I know two minni split will keep my bus 70 on 100 degree day and one roof top would not keep it but 80+. I'm not a inverter guy---food for though---no surge ---low amp draw--. Bob"

[somewhereinusa]

My experience is about the same. Start amps is 2 and very slowly climbs to 7. That's the highest I ever saw on cool. I have run both on 30A. Rear condenser is under my bed, I get more of a "sense" that it is on rather than hear it. If the radio is on you can't hear the indoor unit.

[Njsurf73]

After reading the last 2 posts, I am going to look at a way to budget them in. It may not be right away, but I will go this route.

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