I am doing my own ductless mini split installation (first-time). I have a dual zone unit so there are two air handlers with two ac line sets. One line set is 25' long and the other is 15' long.

So the question is must I cut the excess line set when connecting to the condensing unit outside of the house? Or can I just leave the excess coiled-up outside near the unit?

For the 25' line set, the coiled-up length would be about 4'. For the 15' line set, the coiled-up length would be about 9'. This is a total of about 13' coiled-up for the same condensing unit. Would that be an issue?

Appreciate your reply.

 

I would cut it. Coiled up line set makes a good oil trap.

 

The problem with cutting the lines is your ability to make perfect flared connections on the shortened tubing.

Or are you going to silver-solder the connections?

 

I would have to buy a flare tool and learn to make a sort of good connection. But I would apply Nylog to make sure it doesn't leak.

 

Does the paperwork state how much the condensing unit is precharged with?

15ft/25ft? You should try to make total lineset distance as close to the precharge as you can. Too much lineset and you may need to add refrigerant and vice versa.

If you have excess copper from the loops, practice some making some flares on that...

I am assuming you also have a vaccum pump....

 

Thanks JJinPA for that thought. I couldn't find how much it comes precharged with in the manual. But I checked on their site and it mentions that all of their units come precharged for the included length of line set.

So they shipped two 15' totaling 30'. That means I will have to cut. :-( Yes, I'll have to practice flaring on the excess tubing.

And yes, I bought a pump, but will have to watch few YouTube videos first.

Thanks again.

 

Think twice before you cut it. I would not cut it, once you cut it open you will have to recharge the system, do you have a license to do that type of work ? Just a pump is not enough, you need few more tools and some AC skills to complete the job. If you really want to cut it, get an AC tech to do it.

 

Coil up the excess but have the coils laying flat, that will preclude the trapping of any oil.

 

He is not cutting a charged lineset. The refrigerant is still locked away in the condenser. I would not tell ANYONE to cut a lineset that was full. He is "sizing" the lineset for install. The closer you get to what the unit is precharged with, the less you have to mess with refrigerant charge to get best efficiency.

And if he DOESN'T cut, then he probably DOES need to have refrigerant added if lineset is too long.

 

JJ, did you read this?
The unit is factory charged with the proper amount of refrigerant for the included lineset(s). Cutting the linesets would then require REMOVING some of the refrigerant.

 

"One line set is 25' long and the other is 15' long."

I assumed he is not using the included ones. That is 40ft. Not 30ft. Included was 2 x 15ft.

Unit came with 30ft of lineset, so if he has 40ft, he either has to cut or have refrigerant added to make up for the 10ft.

 

That is the problem, assuming facts not yet in evidence. We are both guilty of this. IF he bought the condenser, evaporator units and linesets as a factory package then the condensing unit should have the proper charge. On the other hand, if he bought a factory unit with linesets included BUT decided to use different linesets with a total length different from the total length of factory linesets THEN he has a problem. This is why I often state that anything other than the refrigerant connections are definitely DIY but the refrigerant system itself is best left to a pro.

 

I agree...

I will list the assumptions so OP is clear.

New install.
Total lineset installed is now 40ft.
Unit came with a total of 30ft of lineset.
Linesets are same size.

I am just saying that if length is not adjusted, the charge will need to be...If above assumptions are correct.

 

Is coiled line set really that big a problem ? I have seen many installations, those line sets going up and down and coiled in so many different ways, but they all seems work fine.

 

The unit is designed for x amount of lineset. The further you stray from the precharge, the more problems you will encounter if charge is not adjusted.

10ft is a good bit of extra. My home system, for example, called for 6oz of refrigerant for each extra foot of lineset beyond 15ft.

So yeah, if it were a foot off, no biggie. But 10ft+ and it probably will need a shot.

It will work, just like many over/under charged systems do. Inefficiently and with a shorter lifespan.

 

My apologies for not being more clear.

This is a new install. There is refrigerant in the condenser, but not released into the lineset yet. I am just beginning to attach the linesets to the air handlers, then to the condenser next.

The shipped unit came with two sets of 15' totaling 30'. But because my one air handler is on the 2nd floor, I had to purchase a longer 25' lineset. But I won't be using 25', instead I will use 21' cutting-off 4'.

The unit on 1st floor doesn't require 15' of lineset, instead I will use only 6' cutting-off 9'.

The total lineset length after all said and done for 1st and 2nd floors should be about 21' + 6' = 27''. That is close to what the factory shipped of 30'. So that is the idea and I can stick close to the factory's lineset length.

Would that be okay?

Just fyi: I emailed to the place I purchased the unit to get their opinion. And they came back saying it's up to the installer. There is no harm in leaving the excess coiled-up behind the condenser.

It sometimes is confusing to me as a beginner, but then I guess I have to use some common sense.

 

I always thought rolled tubing was a bit of a hack job.Even hidden in a attic or basement. Do it right or have it done right.

 

The system is designed for 30ft. Shoot for that. A little over or under won't kill it. But if you want it to work as close to design, with no adjusments to the charge, closer is better.

Do yourself a favor. Don't use a cheap flare block either. It will make...cheap/rough flares and will piss you off.

Make sure your linesets are sealed up if not connected yet...You want as little moisture(or anything for that matter) in there before you evacuate the lines.

Do you know anyone with nitrogen to test for leaks? You can see if it holds a vacuum, but IMO, it is best to have it charged with nitrogen and test for leaks at the fittings to be sure.

 

Hi JJinPA.

Just yesterday when I was doing the electrical wiring on the condenser unit, I saw a small chart on the back of the unit. It said "Pre-Charge Pipe" of 15m (49.2 ft). And then gave a small formula to calculate additional refrigerant for added lengths.

I was like why in the world this wasn't mentioned in the manual to begin with!!!!! We spent all this time back and forth without this main information. I guess that's expected for the Made in China stuff.

Anyway, so the charge is not really based on the length of the lineset that the unit came with. It is what is written on the unit in plain English.

Case closed, finally.