Multi-zone mini-split?

[SeanH]

Hey everyone!

I am beginning to research installing a minisplit into my 1300sqft garage. It's attached to the house (in a manner that makes it less obvious) so it is shaped like an L. One side is basically a 2 stall garage, 24x25. The other side is almost a double deep two stall (and the deep side is where my lift will go). Fully insulated with R13 in the walls and R30 in the ceilings.

I was considering a 21k mini-split system with 2 zones (12k and 9k) https://iwae.com/shop/21k-btu-23-se...ystem-2-zone-wall-mounted-9k-12k-ha18624.html, but I see they get more expensive with multiple zones. Should I bother with two zones, or just get one big condenser and place it where I would likely spend most of my time? Thoughts?

Reason I like the two zone system is it will help distribute the cool air around the garage better than a single unit.

 

[Yankeefarmer]

When we added AC to our house two years ago, two contractors offered two separate systems, while a third proposed a multi-split. Prices were all within a couple percent of each other. We went with the single condenser, two head system, principally because the equipment placement and line routing he proposed were the most attractive, and he was the most pleasant during discussions. We are happy with our system.

Based on our experience, I wouldn’t hesitate to go with a multi system, unless you can install two separate systems at less cost. Distribution of the conditioned air is critical to being satisfied.

 

[LS6 Tommy]

It all depends on aesthetics for me. I personally would prefer two separate units. It usually offers more equipment placement options and no issues with zones having to alternate instead of running at the same time (although not all brands have that issue).

Tommy

 

[SeanH]

When we added AC to our house two years ago, two contractors offered two separate systems, while a third proposed a multi-split. Prices were all within a couple percent of each other. We went with the single condenser, two head system, principally because the equipment placement and line routing he proposed were the most attractive, and he was the most pleasant during discussions. We are happy with our system.

Based on our experience, I wouldn’t hesitate to go with a multi system, unless you can install two separate systems at less cost. Distribution of the conditioned air is critical to being satisfied.

Yea, that's exactly my thinking. If my garage were one big square it might make sense, but being able to distribute the cool air means it should cool off faster and evenly.

Thanks guys.

 

[Gentleman Adventurer]

Just had this discussion with an installer. 2 separate units seems to be the best recommendation. About the same cost as a multi head, but more reliable, and easier to troubleshoot and repair separate units, when those needs arise.

 

[yeldogt]

With two units == you have two units .... two of everything. I really don't see how any of this is going to be less maintenance.

In reality -- properly installed and a good unit you should not need maintenance.

I also don't get the -- if one fails .. you have the other. This is always the reason for the one in the attic vs doing a zoned system in the basement -- guess what .. one does fail .. the attic typically.

Do a proper load calculation ... determine what each area will need and how you will use it.

I have done three multi head system and a few singles -- there are reasons for both. The multi have been three heads. You really have to look at the outputs at different temps -- off times the multi head can run in the sweat spot.

On my new building -- I'm most likely doing a double and a single. For two reasons --one the single is on the other side of the building and it not going to be used all the time.

The nice thing about the better multi -- you can over factor the heads. All three of mine have 3x12k heads run from a 30k BTU compressor. This keeps the unit running in its sweat spot and still able to provide the capacity when required.

Three 12k units would be running way out of the sweat spot most of the time -- in some cases many of the units can't ramp down low enough ...

So there is no one answer -- it depends on the load and the unit. Don't oversize them -- especially with singles

 

[theoldwizard1]

... I see they get more expensive with multiple zones. Should I bother with two zones, or just get one big condenser and place it where I would likely spend most of my time?

Zoning is important for comfort ! It will save energy, if you can shut one off for part of the day.

The down side to multi-zone systems is that they are less efficient. Check the SEER numbers. While more expensive, two smaller systems will same money when operating.

 

[yeldogt]

Zoning is important for comfort ! It will save energy, if you can shut one off for part of the day.

The down side to multi-zone systems is that they are less efficient. Check the SEER numbers. While more expensive, two smaller systems will same money when operating.

I have pointed this out before -- the ratings are best case. No unit gets the rating through out the range.

If I do three 12k heads ... and they spend most of the time trying to run at 5k ... they are not getting max efficiency. My three head would be in the 1/2 range ... it really depends on the load ... you want to match the load