Who’s familiar with mini split AC

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Rene T

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What you need to remember is whether it is one condenser or two, the power requirements will be the same. Virtually all but the cheapest units are inverter driven, one unit driving two indoor units will be working just as hard as two separate systems. At 20' from their preferred sitting location, I would not expect any issues, certainly with the quality brands. When you get down to your property, have a wander and listen to other people's units.
I’m not a electrician but if it takes 30 amp power to one condenser wouldn’t two be drawing 60 amps thereby tripping the 50 amp main circuit breaker on the pedestal?
 

TonyL

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Don't think of a split system like a conventional RV air conditioning system. I don't think RV units have inverter driven compressors. When the outdoor unit starts, large capacitors charge and draw quite a heavy current for an extremely short time. The compressor starts at low speed and with virtually no power surge. Most small (3-4Kw output) systems in the UK will run on about 5 to 6 amps, probably double with US voltage. If your installation doesn't have room for two outdoor units, multi-split is the way to go, or you could stack the condensers.
 

Rene T

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Don't think of a split system like a conventional RV air conditioning system. I don't think RV units have inverter driven compressors. When the outdoor unit starts, large capacitors charge and draw quite a heavy current for an extremely short time. The compressor starts at low speed and with virtually no power surge. Most small (3-4Kw output) systems in the UK will run on about 5 to 6 amps, probably double with US voltage. If your installation doesn't have room for two outdoor units, multi-split is the way to go, or you could stack the condensers.
Soooooooo much to think about. Wish I was in FL right now although it going to get hot today like every day but not hot like in Arizona
 

Ex-Calif

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What a great and helpful thread.

Maybe stating the obvious but the interior evaporators will also need drain plumbing for condensation.

I live in Asia for over 25 years and split type units were the norm. Biggest issues were blockages of the drains and interior leaks. Make sure you can clean them out.
 

Rene T

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I did have one more question for you Tony but I think Ex-Calif answered it already. My question would have been can the evaporator be mounted vertically but now I see where there is a condensate drain hose so mounting it vertically probably would not work.
 

TonyL

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No, you cannot mount it vertically. The indoor unit has an inbuilt drip tray for the condensate to run in to from the coil. As Ex Calif said, you need pipework to take it away, or fit a condensate pump if a gravity drain is not available. Leaving the coil to get very dirty or poor filter maintenance can cause blocked drainage and water spill from the unit. Quite often, the installation engineer would make a good job of the refrigerant install and then ruin the job by bodging the drainage.
 

Ex-Calif

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A+ on the dirt thing. 90% of the blockages we had were black scum. Dirty urban air & coils washed by condensate was a great recipe for goo. We'd also get a variety of bugs and critters in the mix.

We ended up putting filter change, coil cleaning and drain swabbing on a monthly basis. Humid Asia (like Florida) created lots and lots of condensate.
 

Rene T

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Do they put some type of plug with a bunch of real tiny holes in the end of the condensate hose to keep critters from getting up in there? I would either do that or run the hose so that there is a built in trap like some people do with their stinky slinky hose
 

Ex-Calif

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Do they put some type of plug with a bunch of real tiny holes in the end of the condensate hose to keep critters from getting up in there? I would either do that or run the hose so that there is a built in trap like some people do with their stinky slinky hose
I reckon the problem with any critter screen is it would just allow the sludge to form quicker.

As Tony said a condensate pump would be nice but it would have to be located very close to the coils or the inlet side would sludge up. The output side would be great because positive pressure would overcome critters and sludge arguably.

I personally always thought the drain lines were too narrow, like 1/4" ID IIRC.

All in all best medicine is lots of prevent maintenance. I should add that one company that did this for us used low pressure compressed air to blow out the lines. Some of the runs were quite long going from deep inside the apartment to the balcony for example.

Not to get too boring but in Asia poured concrete was the construction method of choice and most of the time all these lines were simply buried in the pour. A nightmare when a leak occurred because the jackhammers had to come out...
 

TonyL

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In the UK it's 20mm for gravity drain. If it's pumped, 10mm braided hose is used.
 

Rene T

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Can the condenser be installed right up against the wall? It looks like the end has to be left open and of course the front. I’ve never seen a picture of the back of one. I would probably leave it out about 4” just so I could wash the skirting behind it and to blow out any leaves which may accumulate out back.
The excess refrigerant lines would be behind the skirting and would come out just where it makes up to the condenser.
 

TonyL

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The condenser needs clearance behind it to allow air flow over the coil, 4" is fine. What excess pipe, an engineer should cut and flare the pipes to length. If they are using pre-insulated and pre-made pipes, find another installer.
 

Rene T

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The condenser needs clearance behind it to allow air flow over the coil, 4" is fine. What excess pipe, an engineer should cut and flare the pipes to length. If they are using pre-insulated and pre-made pipes, find another installer.
Yes I remember what you said about the pipes. If he does cut them to length he could leave a little extra and that would be hidden behind the skirting.

Tony, I just happened to think. Couldn’t you come over here for a couple of days on a work Vusa? ✈️✈️✈️😂🤣😅
 

TonyL

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If only the CBP would believe I would do it for free. Don't know if that still counts as work🙄
 

Rene T

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One other question Tony . I’m concerned about if we lost power for a short time in FL and I’m in NH, will the AC’s start back up on their own and revert back to the previous settings? I did read about one brand that specified it had auto restart but they don’t all specify that. Thanks
 

TonyL

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I would need to check, but I'm fairly certain that Mitsubishi units do have auto restart after power failure. That's why I fitted them in I T rooms. I also fitted one for a friend of mine, I'll get him to do a test and let you know.
 

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