Mini Split installation......

[Ihateclevernames]

Gents, I am a bit out of my lane here in regards to HVAC........

However I figured that this was a good place to start without getting berated for my questions somewhere else.

Anywho, Once I finish half of my old garage, I want to add a mini split HVAC unit in order to make it a bit more bearable in the summer and winter. I have installed these units here in Afghanistan out of desperation, however I really have been just guessing when it comes to anything outside of the installation instructions.

The electrical: Easy

The connections and mounting: Easy

The releasing of the refrigerant: Hit or miss based on my capability

Some of the ones that I have installed work fine, blow cold air and heat well. However some of them don't. I don't know if I did something wrong during the release or fill, or what.

My question is me wondering if this is something that I can legally install myself and have a HVAC tech come out and check the refrigerant levels and fill if needed once they release the refrigerant. Basically If I can do everything aside from releasing the refrigerant and turning it on, then have him take over........it would save me a great deal of $$$$$$

The last price quote I had was in the $3500 range. Which I feel is absurd when the unit sells online for around $1400.

Thanks!

 

[55bigblockcid]

Yes you can do it yourself .
Whether it is legal or not in your area I cant say.
You should check on that.
The reason your installs may be hit or miss could be a number of things,for one are you pressure testing your piping after you have it connected to the indoor and outdoor unit ?If not you may have leaks and losing the refrigerant.
Most mini splits come using R410a refrigerant,which runs at higher pressure than say r22 there fore will leak easier due to being a higher pressure.
Are, were ,the line sets that were ran too long?
The mini splits come pre charged with refrigerant for a maximum line set length,You can pipe farther but the charge should be adjusted accordingly.See manual for unit.
Are you evacuating these systems down to a 400 micron vacuum?
If not you will be introducing non condensables into the system which is not good for the compressor windings thereby shortening the life of the system.
I have had guys do all the install themselves ,and then I went and pressure tested the system ,evacuated the system and released and adjusted the charge.
On the systems I have done I find it better to weigh the charge in to the manufacturer specs for systems I thought were either low on gas or completely out.
That is something most [ do it yourselfers] cant do.
Good luck.

 

[JakeKohl]

R410 systems are a little more sensitive to having the proper charge. If you shorten or lengthen the line set for which the system was precharged for, you will need to add or remove some refrigerant. This is probably less important than doing a proper pressurized leak check (with nitrogen) and completely evacuating the system with vacuum before releasing the charge. I seriously doubt there are any laws against you installing it yourself - but to protect your installation, you should have the right methodology and equipment.

Some guys here have found pretty good cost savings by doing the install on their own but hiring an AC guy to leak check, evacuate, and properly charge the system. The physical installation of the equipment and running the linesets can require some work - so I'm not surprised to see a $3,500 price tag on it.

 

[rlitman]

If you purchase a pre-made lineset, you must cut off the flare ends, throw out the flare nuts that come with it, and install the flare nuts that came with the R410a unit. Look closely, and you will see that the new style flare nuts have a thicker shoulder made for the higher pressures of R410a.

Oh, and you cannot run UF cable directly to the unit. I put my disconnect on the outside wall, and ran LFMC conduit to the compressor.

 

[Ihateclevernames]

Thanks for the advice guys. I wish I had the tools to do said things here in Afghanistan, however I have to make do with what I have and being that I am in the middle of no where.........

It's not much. I am pretty much limited to what comes in the box and a basic set of gauges.

Anywho, I am more concerned with my place when I get home. I will look into the codes aspect of it and then get some pricing info on the HVAC service fees. I have been using the Chigo models here, and I wouldn't dare put something like that in my house as they are pretty touchy. Anyone have any suggestions for a reliable brand that won't break the bank?

 

[Riley]

Howdy! Thanks for your service!

I, with assistance, just installed a 9K Mitsubishi mini split in an equine facility lab and collection shed, about 20X40 overall.

I've done a heat pump/high efficency furnace install before which required some "more professional that I was equipped for" assistance with vacuum and brazing but overall it was a matter of following the instructions for electrical and venting.

My recent project required welding assistance on the exterior bracket and some material for the bracing using 3in pvc on an exterior of a corrugated sheet-metal building, the actual install was cake.

One thing I had missed was the fact that there are not one, but two stop valves to release in the system, one for the gas, this set was pre-charged for 25ft of line set, and another for the liquid.

I felt pretty stupid once I reviewed the instructions and discovered the reason it was not getting colder was my error in not releasing both of the stop valves. Once free, it does a remarkable job cooling the entire space even though it is undersized for that application.

The lab has three fixed vents as well as a 4x3 sliding window that is generally kept open which facilitates the air conditioning. This include humidity removal which is a real concern due to the possibility of mold etc.

I'd say with this experience as a guide, buy the exterior bracket with the unit, make sure your drain declines from the unit to the collection point, use a standard line set cover and have the electrician wire in the pig tail as he does the disconnect. Leave the disconnect out until the unit is wired in.

Enjoy the cold!

 

[mobiledynamics]

I would do the electrical, mount the compressor, hang both condensor/compressor, rough in the linesets.

However, I would just sub a tech to make the connections and turn-up the system.

Just brazing the connection and proper charge is critical