Do it yourself mini split heat / AC

[kwired]

I have heard of these. I am unclear how the line set is connected. There is perhaps some misunderstanding about "no refrigerant needed" because they all come with refrigerant that will work up to a certain line set length. I guess you could have a line set already evacuated/filled as needed, but how do you connect it to the compressor?

My understanding is they are either quick connects or threaded fittings of some sort with valve in the fittings. Line sets are pre filled, no evacuationg needed. Bad thing would be you need to find a way to route any excess line as you can't cut them. If you do cut them you would then need to evacuate the system (or at least the portions you exposed to atmosphere) to get best performance results anyway.

You don't need to know how to tell if unit is charged properly as long as you don't let contents leak out during installation. Is sort of not much different than a self contained unit that is already charged when you purchase it. Once leakage has occurred - you need to know how to properly recharge, and maybe even know how to fix whatever caused the leakage.

 

[electrofelon]

You don't need to have the lines evacuated unless you are changing from one type of free on to the other. There's really nothing in the air to contaminate anything inside the lindset. Besides, they come with caps on the ends

I've installed close to 2 dozen many splits. I used to hire my son (a certified HVAC tech) To vacuum the lines and check the pressure. Not anymore.

Easy peasy

Oh my, you don't evacuate the lines. So everyone in the HVAC industry is doing this unnecessarily?

 

[kwired]

Oh my, you don't evacuate the lines. So everyone in the HVAC industry is doing this unnecessarily?

Well it probably will still work, but probably not as efficiently and any moisture that gets in is not good for certain components either.

Non condensable gases would still be circulated through the system and take some power to move through the system, but since they won't evaporate and condense they won't be moving as much heat as the refrigerants do making overall efficiency go down.

 

[James L]

So everyone in the HVAC industry is doing this unnecessarily?

Pretty much.

 

[hbiss]

Pretty much.

That's why we are electricians and not HVACR techs.

-Hal

 

[mtnelect]

Some minor steps in the HVAC trade:
1. When you braze always use nitrogen ... then pressurize the system for leaks.
2. Before you charge a system always pull a vacuum ... moisture turns to ice and can damage the compressor.
3. Check for a proper charge ... ductless systems have a different thread size than standard systems.
4. If you want to do a whole house with MRCOOL you will need one condensing unit each room ! I guess you can hang them all on the outside walls.

 

[GeorgeB]

So does the connection makeup have a way to expel the trapped air between the male and female connectors as it is tightened? Or do you just end up with a small amount of atmosphere mixed into the refrigerant system?

Those fittings look similar to the face-seal zero leak hydraulic quick connect fittings with which I'm familiar; less than 0.1cc of "fluid" loss coupling OR uncoupling.

 

[mtnelect]

Some minor steps in the HVAC trade:
1. When you braze always use nitrogen ... then pressurize the system for leaks.
2. Before you charge a system always pull a vacuum ... moisture turns to ice and can damage the compressor.
3. Check for a proper charge ... ductless systems have a different thread size than standard systems.
4. If you want to do a whole house with MRCOOL you will need one condensing unit each room ! I guess you can hang them all on the outside walls.

MRCOOL - Beirut Style !

 

[wwhitney]

4. If you want to do a whole house with MRCOOL you will need one condensing unit each room ! I guess you can hang them all on the outside walls.

Perhaps true in the past, but now they have an outdoor unit that can connect to up to 5 indoor units.

DIY 4th Generation Multi-Zone | MRCOOL

Comfort Made Simple

mrcool.com

Cheers, Wayne

 

[mtnelect]

Perhaps true in the past, but now they have an outdoor unit that can connect to up to 5 indoor units.

DIY 4th Generation Multi-Zone | MRCOOL

Comfort Made Simple

mrcool.com

Cheers, Wayne

Looks Good !

I am a proponent of ductless systems and against ducted systems. But a DIY installation for the whole house I am skeptical.

 

[Buck Parrish]

Perhaps true in the past, but now they have an outdoor unit that can connect to up to 5 indoor units.

DIY 4th Generation Multi-Zone | MRCOOL

Comfort Made Simple

mrcool.com

Cheers, Wayne

That's right. They've been around for a while . I've wired one outside condenser that heated cooled three indoor units.
But the hvac guy put the freon in it. It was not a DIY'er type. Although looks like Mr Cool has them now.

 

[wwhitney]

I am a proponent of ductless systems and against ducted systems.

Seems like it depends on the configuration of the conditioned space--how do you ductlessly handle a bedroom level with 4 or more bedrooms? A head in each bedroom is trouble, particularly as the smallest Mr Cool head is 3/4 ton (at least for the Multi-Zone system I linked to).

Cheers, Wayne

 

[mtnelect]

Seems like it depends on the configuration of the conditioned space--how do you ductlessly handle a bedroom level with 4 or more bedrooms? A head in each bedroom is trouble, particularly as the smallest Mr Cool head is 3/4 ton (at least for the Multi-Zone system I linked to).

Cheers, Wayne

Diakin is also very versatile ...

 

[LarryFine]

Vacuuming a non-precharged system is important to remove moisture, not just air. Reducing the pressure makes moisture evaporate at lower temperatures, and the vacuum should remain for a period of time.

 

[winnie]

There are enough reports of systems 'working fine' without evacuating that I figure it is roughly the equivalent of installing a 14ga receptacle circuit on a 30A breaker.

It will work. It will have lower performance, shorter life, and reduced margins, but it won't cause instant failure and destruction.

It probably makes a difference the ambient humidity when you do the installation, and how long one leaves the pipes open.

Apparently an old school R22 technique was to simply purge everything with refrigerant, no vaccum needed.

But really, a vaccum pump and micron gauge are pretty cheap. There is no reason not to evacuate a system even for a DIY installation.

Jon

 

[Amps]

I installed them on my house six years ago. Still working fine. I used Pioneer. I did a ton of research and found all the DIY use the same invertor and at that time Pioneer was the best price. I bought a tank of nitrogen, gauges and a vacuum pump. The line sets are pre-made, all compression fittings. The longest line set that can work with the pre-charge is 25ft. After 25ft more refrigerant needs to be added. I designed my system around the 25ft line sets or less. Once the lines were connected, there are access ports on the outdoor unit used to connect gauges, etc. I pressurized each line with nitrogen, tested for leaks, then vacuumed each line to remove moisture. Going from window AC to mini splits was awesome with the addition of heat in the winter. Using less firewood as well.

 

[g-and-h_electric]

As the electrician for an HVAC shop, I am going to ATTEMPT to 'splain the precharged and non precharged mini split systems......

1 All of the "DIY" units come with enough charge for about 25 ft of line set
2 the units that have "precharged" line sets, basically have a "tin foil seal on both ends of the lineset, and the connection of them breaks the seal, and allows the refrigerant to flow.
3 The systems that come without the precharged lineset have the refrigerant in the compressor. These systems should be leak checked with nitrogen ( trust me, the flare fittings have to be REALLY tight to not leak), then evacuated to remove any and all foreign substances in the lineset.
4 a full and proper vacuum is 500 microns....... gone are the days of a mechanical gauge pinned at the lowest vacuum point, and calling it good.

After the above is done open the service valve and all SHOULD be good!

Just did one for a friend ( he is an electrician, and did his own wiring), and what "annoyed" me the most was the non standard fitting to connect my gauges to, and only a fitting on the suction line. I guess I got spoiled doing regular systems where I can check hig and low side pressures and their respective temperatures to verify proper charge.

I promise I will try to remember and report in after I install my "new" hvac equipment after labor day, and we will see how good an installer I am as oppose to a service guy.....


Howard

 

[kwired]

Looks Good !

I am a proponent of ductless systems and against ducted systems. But a DIY installation for the whole house I am skeptical.

Do something wrong and it maybe cost you some $$$ down the road. Do something wrong with electrical installation risk of taking a life tends to be higher. Repairing/replacing the brakes on your own vehicle sort of similar in many ways.

Some professionals cut corners that their industry sets as standards for whatever reason. Some industries or regulatory overseers set certain standards pretty high whether truly needed or not.

You do need to educate yourself to some extent on a lot of things and at least ask questions when hiring someone to do some these things for you or you may be taken advantage of.

 

[OldSparks]

In the FWIW department, and this was in the 1995-2003 era, I had two mini-split systems. One for my shop and one for my office. Both were professionally installed and maintained with compressors on the roof. Both of them froze-up on separate occasions more than once. I finally had them ripped out and replaced with a forced-air system. I certainly hope that the mini-split systems have improved since then, but an HVAC tech I spoke to just last year agreed with me that they are, shall we say, much less than optimal.

 

[winnie]

In the FWIW department, and this was in the 1995-2003 era, I had two mini-split systems. One for my shop and one for my office. Both were professionally installed and maintained with compressors on the roof. Both of them froze-up on separate occasions more than once. I finally had them ripped out and replaced with a forced-air system. I certainly hope that the mini-split systems have improved since then, but an HVAC tech I spoke to just last year agreed with me that they are, shall we say, much less than optimal.

By 'froze up' do you mean the inside coils getting covered with frost/ice during AC use, or do you mean the outside coils getting covered with frost/ice during heat pump use, or something else?

As mentioned above I am in the process of a DIY minisplit install, and am curious about the failure you experienced.

-Jon