DIY Mini Split A/C Install Help Thread

[chrometrichs]

This thread is for anyone who needs advice or help with installing their mini-split a/c's. Hopefully, this thread will be the motivation I need to finish installing mine. :clapping


My first question.... The wiring diagram for my Friedrich M18CF, shows a disconnect switch between the indoor and outdoors unit, pictured below. What kind of disconnection switch is this? and why would you have to have an additional disconnection box between the indoor and outdoor unit, when you have a disconnection fuse box running between your power line and outdoor unit. Since the outdoor unit supplies the indoor unit with its power its seems redundant to have another disconnection switch between the units doesn't it?

 

[mcattak]

Good luck chrome...Sounds like clowntown has some DIY knowledge...

 

[Lost]

If you running it 24/7 you wont need one right? I dunno, my cheap chinese's don't have that in their diagram..

 

[Midnight_son]

Chrome, that's exactly what it is ... Redundant. It's an added saftey, basically for someone servicing the unit. Kind of like lock out tag out. A person working on it would pull the disconnect, service the unit, then replace the disconnect. No chance of getting juiced should someone flip the breaker on at the box.

 

[TrichromeFan]

Chrome, that's exactly what it is ... Redundant. It's an added saftey, basically for someone servicing the unit. Kind of like lock out tag out. A person working on it would pull the disconnect, service the unit, then replace the disconnect. No chance of getting juiced should someone flip the breaker on at the box.

Maybe something like this:

 

[Farmer Jon]

Heya Chrome,
Just as Midnight said its not really needed, i have a mini split in my room that i installed myself...so simple.
you will be hooking into the breaker panel and that is all the disconnect you will need the hardest part is flaring the copper right and making sure its free of leaks (soapy water will work) make sure the edges of the flare are smooth and that the connections are tight but not to tight as they will crack fairly easy. Most of the units around come pre charged but if the one you have is not, the tools you will need are easy to obtain. You will need a pressure gauge and a vacuum to remove any moisture from the lines (it can turn to ice and kill the compressor ) wire size will be dependant on the size and distance of the unit. There are a few online guides to aid you and im sure you will be able to handle it with little to no difficulty.
And by the way, keep up the good work!

 

[chrometrichs]

Maybe something like this:

Ya thats the same box I'm using to run power between the breaker and the outdoor unit. It seems like the disco switch the manual is referring to between the indoor and outdoor units might be something as simple as a light switch. Regardless, I'm going to call the manufacturer and see if they can shed some light on the subject.

Heya Chrome,
Just as Midnight said its not really needed, i have a mini split in my room that i installed myself...so simple.
you will be hooking into the breaker panel and that is all the disconnect you will need the hardest part is flaring the copper right and making sure its free of leaks (soapy water will work) make sure the edges of the flare are smooth and that the connections are tight but not to tight as they will crack fairly easy. Most of the units around come pre charged but if the one you have is not, the tools you will need are easy to obtain. You will need a pressure gauge and a vacuum to remove any moisture from the lines (it can turn to ice and kill the compressor ) wire size will be dependant on the size and distance of the unit. There are a few online guides to aid you and im sure you will be able to handle it with little to no difficulty.
And by the way, keep up the good work!

Thanks Jon, I've flared my copper tubing, but I haven't checked it for leaks yet, is there a way to check it for leaks before you start vacuuming the lines? If I do find theres a leak I'm guessing I'll just need to re-cut the copper tubing and re-flare the ends, right?

 

[TrichromeFan]

Ya thats the same box I'm using to run power between the breaker and the outdoor unit. It seems like the disco switch the manual is referring to between the indoor and outdoor units might be something as simple as a light switch. Regardless, I'm going to call the manufacturer and see if they can shed some light on the subject.

chrometrichs,
I believe that the pic is what you should use for a disconnect between the outdoor and the indoor unit. It is not a fuse, but just a contact that is removable to shut down in an emergency. You could use a regular switch of sorts, but it will have to have 2 separate sets of contacts to disconnect the 240v. This thing is specific to the purpose, and is cheap too. They do stuff like that so if you are right by the unit, you can shut it down quick. I would agree that it is redundant, especially if you have some sort of breaker disconnect for the power coming into the outdoor unit right next to it s well. BUT, if the manufacturer wants it, and as shown in pic is only $6.47, then I would say F it, and just slap one of those puppies right next to the main unit. Just my 2c.

 

[ncga]

Chrome

My mini split came with the disconnect. Please use one since it is code and a safety issue. Grow rooms work much better when wired to code.

nc

 

[Lost]

Chrome

My mini split came with the disconnect. Please use one since it is code and a safety issue. Grow rooms work much better when wired to code.

nc

How can it be code? Mine didn't even have provisions in the wiring diagram for it? I'm not doubting its code somewhere but I don't think its code here in Cali?

 

[Farmer Jon]

If you get a spray bottle full of soapy water and spray around the fittings/joints if there is any leaks it will bubble. If you find that it is leaking, slowly tighten the nuts until it stops bubbling. If you tighten it to much and crack the flare you will need to cut the flare off and do it again.
befor checking for leaks the unit will need to have the valves open to release the coolant into the lines so be fairly sure that the fittings are tight enough befor you do, so you dont have to get more gas. (its not cheap)
turn the unit on while checking for leaks so there is coolant cycling through the whole system. make sure to check both the outdoor and indoor unit for leaks. After you are sure you are leak free pull a vacuum on the lines and you're good to go.
If you do screw up and need to get more coolant (r-410, r-22, it will say on the outdoor unit what you need) i've found that craigslist is a great place to find it. You need a license to get it from a supply house.
Hope this makes sense!

 

[jo4ey]

A/C Installer Here!!

Thee disconnect you guys are showing is for the A/C tech. when servicing the unit. A/C techs are not electricians and as such are not allowed to open electrical panels!! There for every A/C should have a disconnect within six feet of outdoor unit. The disconnect only need interupt the juice from the panel and not between the indoor and outdoor unit. The wires feeding the indoor /outdoor unit(two hot wires a ground wire and control wire) are generally ran through the same disconnect to save installing a separte junction box.
I can answer any questions!!!

 

[TrichromeFan]

I can answer any questions!!!

OK, here's some::wondering

do all mini splits have to be setup with a vacuum and a gauge?

is there a big difference in brands of mini splits that you have dealt with?

If so, what's your favorite?

-TF

 

[CannaColorado]

cant you also just pull the vaccume and leave it for a few hours to see if there is a drop in pressure? or is this not applicable because the leak would be from positive pressure not negative pressure

 

[Lost]

Canna - Yes. that is the best way. I had a pinhole leak which happens sometimes. Getting a can of no leak and putting it in will be standard for me next tiem I install one. If you have no leaks no biggie, but if you do that stuff will stop the minor leaks. I had a leak at my low pressure hookup :( Kinda common I guess..

 

[CannaColorado]

what, you mean like the slime i put in my bike tires? Thats way tight. do you have a link to some that can handle r410a?

glad to know my plan for checking the vacuum is A ok. Time to do some kundalini yoga : P

 

[HG23]

Hey guys,

I have years of experience with automotive a/c systems which are setup pretty much the same as any other a/c system. To whoever asked about whether vacuuming is necessary, I would say definitly yes. We hold a deep vacuum (about 30 inhg) on our a/c systems for a couple of reasons:

1. Anytime the tubing or other parts that contact the refrigerant are exposed to the atmosphere, contaminents enter and will contribute to refrig. degredation over time. Vacuuming helps remove any dirt/air/moisture.

2. Check for leaks. A big leak will be obvious. Smaller ones will bleed to vacuum off slowly, we usually wait about 15-20 min or longer to check for small ones. Vacuum shouldn't drop more than a couple inhg over a 10-15 min span (at least in automotive a/c).

3. A vacuum must be present, at least with our A/c systems, to fill the system with R134a. I'm not sure if all types of systems are like this, but it makes sense to me because you would want to remove contaminents immediately before adding oil and refrigerant.

Hope this helps somebody out there. Oh and thats something else I haven't seen brought up, do you have to put compressor oil in these mini splits?

Edit: Forgot to say. Based on my experience, I would avoid spraying that "tire goo" like leak sealant into my system like the plague, especially if you don't have to. Yes it might work, but I have seen that it causes more clogging/compressor problems over time than it helps. I would think of it like the tire stuff, ment more for emergencies to limp you back to a repair shop.

 

[heater]

Yes HG23 is right stay away from sealants. Generally if they are used its for a system that is on its last leg.
The key to compression fittings is to keep your connections square and no tension. I use a little vacuum pump oil on the male fittings and tighten snug and add 1/16 turn. Don't over tighten, if their is a leak you can allways snug it down a bit.
If the mfg. has a torque rating as always its best to start there.

 

[Lost]

NONONONO, lol.. I'm talking about the HVAC stuff. The guy said it was pretty expensive stuff. I had a certified HVAC guy fix my stuff a week ago because of a small leak. It took 3 months for it to stop getting cold and it was a newb install mistake, totally my fault. My HVAC guy put it in as a just in case.

In fact my problem was an under tightened fitting. lol!

 

[HG23]

Hey lost,

I knew what you ment, an HVAC specific version of the "tire goo". Not the actual tire goo, lol, you'd have to be seriously out of it to try that. If your HVAC guy put it in and you trust him then that works. It's just been my experience that those types of products are a "limp mode" type of fix. Gotta wonder, if it works flawlessly, why don't they put it in to start?