House a/c, anyone have a 'non-traditional' system e.g. multi-split?

[Trouble Maker]

So, our HVAC in the house is 27 years old, so it's just a matter of, probably a short time until it needs replaced.

 

Our house has our main bedroom upstairs in the attic space, which was added on. In the winter the temperatures variations across the house is Ok. But in the summer it's probably 10~15 degrees hotter up there. There are 2 sends and 1 return for ~250~300sq ft, so I think it's just the fact that it's in the attic. We got a white metal roof put on last year, it seems like it made no difference in temperature difference, but that makes sense sine it covers the whole house. We run a window a/c unit in the summer up there. But, honestly I hate having to deal with that thing. Our house is only ~1200sqft, so it's not large.

 

Overall, I'm really liking the idea of some kind of zone control; at least 2 zones, 1 up and 1 down, but maybe split the downstairs into 2 zones.

 

I'd also like to move out of the way or eliminate some ducts down in the basement. The ceilings are short (7'6") and I'd eventually like to finish down there, but some things need moved first; HVAC, some ducting & hot water heater.

 

I've bee doing a bit of digging, and it seems like a good solution might be a milti-split system, with the duct connected type of indoor unit. Due to ascetics we don't want the units that hang on the wall or are built into the ceiling. There's reasonable crawl space in the attic for an inside unit. There's a kind of concrete shelf that goes around the whole basement perimeter that I'm hoping the downstairs units could sit on.

 

Anyone have any thoughts? Can we still run (smaller) 'whole zone' humidifier on these units? How's the heat capability in the newer heat pump units? We had an 'older' heat pump unit in an apartment and it was just ok for heating.

[LJ]

A mini split with mutliple head units sounds like a perfect system for your house. I don't think you can use a humidifier with them though.

 

Typically the mini-split systems are super high efficiency and can run down to -5 or -10 for heat.

[Trouble Maker]

Maybe my terminology is wrong?

 

Mini-Split=1 head unit (indoor part) + 1 condenser (outdoor unit) per zone, completely separate systems, as many 'sets' as zones

Multi-Split= N head unit + 1 condenser, where N=number of zones

 

Not a perfect picture, but if we went 2 zone, it would be like zones 1 & 3; top is mini-split and bottom is multi-split, I think.

 

http://www.earthenergyinnovations.com/sites/default/files/blog-images/Multi%20Zone%20Vs%20Single%20Zone%20Ductless%20Mini%20Splits.jpg

 

So, I'm thinking multi-split, unless there is some efficiency, or more importantly economical or pratical application reason I don't know about with many mini-splits. I would think 1 condenser=less cost than many.

 

A coworker just did a mini-split for his master suit above his garage since it's blazing hot up there in the summer. His house is fairly new, and they have geo-thermal. So, the ability to add cooling BTUs to just 1 room was perfect for him.

Since our system is old and (figuratively) busted, I would think do the whole system (by multi-split) would work best?

 

You mean down to -10 to -5 F? Do they still have electric emergency backup?

[LJ]

Multi Zone Mini Split

 

You would probably want 3 total heads if the upstairs is one big room. 2 heads downstairs, 1 head upstairs. Wanting to have different temps is your call.

 

The ones we looked at for my In-Laws in Buffalo had heating coils.