Ductless Unit Placement Questions

[mgh-pa]

I'm about to pull the trigger on a Mitsubishi Ductless system for our kitchen/living room area (all total about ~900 sq.ft). I had the local Mitsubishi dealer come out and give me an estimate and recommendations for my situation, and here are my possible options.

First, the floor plan. The orange is the main level where the unit(s) will be placed. It's a tri-level home. The blue arrows show suggested placement of the units. One solution was one large 24K BTU unit placed on the wall in the dining room. The other was to do a split unit (9K one and 12K on the other) in the two blue arrowed locations. Problem with this solution is there is a set of kitchen cabinets that come out right above where "18" is marked on the diagram which blocks movement of air into the rest of the kitchen. We can't place any units on the 20' wall due to height limitations between the ceiling and windows (this would be the ideal situation).

So, what is everyone's recommendation here? Two splits to cover the area more thoroughly with less overall BTUs (21K vs. 24K), or one larger, more centrally located unit (24K)?

 

[begreen]

Can you post pictures of the kitchen and family room walls?

 

[ROVERT]

Which wall is south facing?

If two indoor units fit into your budget, that is the way to go comfort wise. I believe either set up will have more than enough capacity. Did the the contractor run a heat loss/cooling load for your application. Both units seem like they are oversized for 900 sq ft.

 

[mgh-pa]

Here are the pictures (sorry for the quality, they were taken with my cellphone under poor light and compressed with photobucket's instant upload:

Dining room wall indicated on the floorplan above:

This is the wall on the other side of the above picture which is essentially the top left side wall on the floorplan:

This is the 20' labeled wall:

And here is the wall where he mentioned putting another unit (tucked behind the kitchen cabinets (where the other blue unit is labeled on the above floorplan):

Rovert, the "living room" which is actually a gym now is south facing. He did not do any calculations of the sort to my knowledge.

 

[velvetfoot]

This will be for heating and cooling?

 

[mgh-pa]

Yep, both heating and cooling.

 

[begreen]

I'm not so keen on the closeness of the two units. Can one be moved to the living room wall in common with the garage? That would provide a more even heating/cooling and it would put heat nearer to the greatest cold air source, the front door. Also wondering about that same wall side of the family room (marked in red).

 

[mgh-pa]

That would work (putting the unit on the living room wall on the garage). However, I can't put a unit on the top left wall due to the curtain rd and window trim clearance issues (as you can see in the pictures).

Do you think just ONE unit in the dining room wall would be insufficient?

 

[begreen]

That would work (putting the unit on the living room wall on the garage). However, I can't put a unit on the top left wall due to the curtain rd and window trim clearance issues (as you can see in the pictures).

Do you think just ONE unit in the dining room wall would be insufficient?

There is a heckuva a lot of glass on the dining room end. I would go for 2 wall units, one next to the kitchen (upper right, blue rectangle) and one lower in the living room (lower left, red rectangle).

 

[mgh-pa]

Thanks. The salesman/tech speced a 9K for the top right, and a 12K for the lower unit. Does that seem undersized?

 

[begreen]

The sizing really depends on the house insulation, sq ftg being heated and the particular units being specified. Can you post the actual quote including the part numbers for the wall units and compressor?

 

[mgh-pa]

Sure. Here is a copy of the single unit quote:

Mitsubishi Mr. Slim ductless split heat pump - MSZ/MUZ-GE24NA unit with all associated 1.00 $4,115.00
electrical and refrigerant connections
$4,115.00*

And here is the multi-split.

Mitsubishi Mr. Slim ductless split heatpump 2:1 system- MXZ2B20NA outdoor unit with 1.00 $4,695.00
MSZ-GE09NA and MSZ-GE12NA indoor units
$4,695.00*

 

[velvetfoot]

I'm not an expert, but it sounds like a good price for AC and Heating. I'd really like to hear of your experiences with it once you get it installed.

 

[mgh-pa]

I should also note, I do have a Englander NC-30 in the basement below most of the first floor. It is directly below where the top right ductless unit may be placed (there is also a vent there). Would that negate the need for a unit on that wall in that location?

 

[begreen]

I don't think it would negate it. The goal is even heating, especially when the stove is not running. The best of these mini-splits are quite frugal power users. You may be using it a lot more than anticipated.

 

[mgh-pa]

I went ahead and ordered two units. Should be installed in about two weeks. I'll post an update once it's finished.