Owner Building installing Mini Splits in New Construction, Help Please.

[Xringer]

I've seen a few basement lineset installs on the web. (Keeping them out of the weather is a plus).
What you will find in the install manuals, besides a length restriction, is a vertical height restriction.
Since they don't want to be pumping R410A uphill for four or five stories etc..

If you are only dropping the lineset down or going up a few feet, before making the up-turn to your IDU,
it should work just fine. But, your manual may or may not say that, exactly.

I would avoid running a line set via an attic. Since the heat up there
could get way higher than normal outdoor heat.
Unless it was a heating only system!!
If I had to do it, I would try find a way to add some extra insulation to the lines.

When planing your lineset runs, just remember these copper tubes can't
be bent into tight 90 deg turns. They need a good sized radius.
Tight turns hurts refrigerant flow and can kink and break the copper.

[AC_Hacker]

Originally Posted by MaryS

I had to threaten the vendor with calling the BBB to which he immediately changed his position and agreed to return my money and (finally) pick up their damaged equipment...He was wasting my time and not doing what he said he would do so in the end I had to get quite firm and demand my money back.

Companies who sell on-line should exhibit much higher than normal attention to service and customer satisfaction than brick and mortar stores, because we have to trust them, sight unseen, to do what they say they will do.

You would be doing us all a great service, to spell out the name of the company that you have had such trouble with... spell it out so others don't get burned. That is what Angie's List is all about, and it has made things better for everyone... Everyone except unscrupulous vendors, and service providers.

Originally Posted by MaryS

From reading here and looking over Mitsu's on-line install guide, I know there are minimum clearances from the outdoor unit (OU) to the structure. I'm wondering though if there are any concerns in 'ganging' the units together, provided I stick with minimum clearances. Will 'ganging' make the units less efficient in any way?

Yes, they will be less efficient, how much less is difficult to say.

You should consider the minimum clearances to be minimum clearances.

Originally Posted by MaryS

For example, they're all throwing very cold air out (during heating season) - will ganging them make it seem like a really, really cold spot where I gang them on the platform? Or in the 'great outdoors' is this really not a concern?

The more room the units have to breathe, the better. They are bringing in air, and removing some of the heat, and expelling the air. You want them to be able to breathe freely, and to be able to get rid of the cold exhaust air.

In the winter, it will be a pretty chilly walk past the units while they are doing their work... In the summer, just the opposite. Might be a great place to put your clothes line for rapid drying.

BTW, your units will be putting out some water, both in summer and in winter. A strategically located flower bed could take advantage of the moisture.

Originally Posted by MaryS

Must the refrigerent line slope from the IU continuously down to the OU? I didn't see that in browsing the install instructions (don't worry,we'll thoroughly read them before install time) but thought I had seen something like that on one of these forum posts.

Don't worry about slope if the runs are within spec in terms of length and height (as measured from height of OU to height of IU). The diameters of the tubes are carefully calculated so that there is sufficient velocity to keep the refrigerant and lubricant constantly moving through the circuit.

Originally Posted by MaryS

If that is true, I won't be able to have a basement run as one of my possible install options.

Basement run would be good because the lines will be easy to install, and the temperature of the basement is moderate.

Originally Posted by MaryS

If I can't run through the basement, I'm looking at a pretty long run through garage and living space to get to the center of the open-plan 1st floor IU location. Do any of you have installs where you ran refrig. lines through your house (like 40') to the indoor unit (IU). If so, did you run it in interior walls? In a chase? In an attic and then back into the room?

I did all I could to avoid a long run. But I have read about it and there are three issues, refrigerant volume, fluid friction, and heat (or cold) loss.

• Your system will come with a pre-charge already in the OU. There will be enough refrigerant to properly fill the IU and the lineset. Some manufacturers callout the amount of refrigerant you will need to add for every foot of lineset length that goes beyond the standard lineset length. Other manufacturers don't mention any such thing. It's all physics, and I would think that additional refrigerant would be required.
• The fluid friction issue is probably minor and wouldn't be significant unless your lineset was quite a few length-multiples longer than the original lineset.
• The heat (or cold) loss thing is probably small, but I double-wrapped more insulation around the exterior part of my lineset, because it was cheap and easy.

If I understand your intended setup correctly, your OU will be on a platform structure, and there will be some amount of lineset between your OU and your house. I would think that a straight run between the OU and the house would not be such a good idea, since the OU will inevitably have some modest amount of vibration, relative to the house. If you had a bit of a curve or a loop in the line, the linset could absorb the vibration, and that would reduce vibrational stress that could affect the integrity of the flare fittings.

-AC_Hacker