Split-System Air Conditioners?
 

I wonder if anyone has experience with split-system A/C systems.

Here is my situation and why I am thinking of one.
- House has basement, main floor, second floor, and finished attic. Total excluding basement is appx 3,100 sq ft.
- The finished attic is where we have the heat problem. It is the family hang-out room, typically have 3-4 people up there, watching TV, playing with Legos, reading, etc. Plus the electronics (LCD TV, etc) which give off a lot of heat.
- Finished attic is appx 800 sq ft. Appears to have been insulated, but only a so-so job - for example, no ridge/soffit vents. Five skylights, fitted with black-out blinds. Various smallish (20" x 20") windows set in dormer/alcoves, but only one opens.
- House has central air but, being an old house that was retrofitted, the ducting is not ideal. Only one small duct (appx 30 sq in) in the attic. There isn't any room to run more or bigger ductwork to the attic, not with the existing interior wall layout anyway.
- Central air does a great job on the main floor, a so-so job on the second floor, and not much effect in the attic. If I close all the main floor vents and some of the second floor vents, it helps a bit in the attic but still doesn't do much. If I point fans up the stairwell from second floor to attic, it helps a bit more. An exhaust fan in the sole opening attic window is also a minor help. But even with all of this, the attic doesn't get enough cooling.
- At outside temps of 90F, the attic is kind of warm even with the A/C running. At outside 95F and higher, the attic is too warm.
- And, in order to get the attic down to "kind of warm", the central A/C has to run a lot. This seems like a waste, since the rest of the house is cool enough. I'm basically running the whole house central A/C just to cool the attic.

Thus, I was thinking of installing an air conditioner in just the attic. I think I need something like 15,000 BTU for that size room.

Window unit? These are relatively affordable, I see 15,000 BTU units cost around $500. But there is no exterior window in the attic that can accommodate a window A/C unit. There is an exterior southern-facing wall where the stairwell comes up, I guess the wall could be cut and a window unit mounted there. Downside: I hate the look of exposed window AC units on the exterior of a house, though. And the A/C condensor side would be sitting in direct sun, on that south wall.

So that is why I was thinking about a split-system unit. The condensor (heat pump) could sit on the shaded northern side of the house, next to the condensor for the central A/C. Downside: Looks like 18,000 BTU single-zone split-system A/C units cost around $1,500, plus installation of course. It would look weird to have two condensors, indeed it seems silly to add another A/C unit when we already have central A/C.

I am going to have the A/C guy look at this situation when he is out here tomorrow. Maybe there is an easier or more sightly solution. But what do folks think? Anyone have a similar problem?

Multi zone A/C-heat is the norm here in TX, so nothing strange at all.

Your issue would seem to be the ducting that would be needed. It is so much harder to retrofit.

If you were to redo everything you might go 3 zone with 3 smaller units, better ducting flow and have a lower utility cost. But the conversion cost would be the barrier.


Split system not multi zone........ Never mind.

If I understand correctly, the split-system doesn't use any air ducting. The refrigerant runs in insulated pipes from the exterior condensor to the evaporator unit mounted in the room. I don't mind having some relatively unobtrusive pipes running up the exterior wall to the attic level. I could have them routed alongside the chimney and they wouldn't be too bad-looking.

Something like this
http://www.ajmadison.com/cgi-bin/ajmadison/AMS180HR.html

Window units are very inefficient and will drain your wallet so quick, you wish you'd have bought a central system.

I used to live in the South where people were serious about A/C. Two story homes all had two completely independent a/c systems. Granted, this was 10+ years ago.

George

your talking ductless AC?

everyone in asia has them. they are wonderful. my wife aunt as one system split into 4. awesome to cool only the room in use, and not the entire house. i am going to get one.

consumer reports just gave the nod to LG. the downside? i think they are a bit on the noisey side. with central air, the fan is far away, and you cannot hear it. not so with this system. loud. i also think the units need to improve a bit in the looks department. do they have a countersunk system yet? still, i hate melting, and sweating away..i will buy one in the next year or so. prices are coming down.

i did also see a system to retrofit into older homes. it uses ducting, but the ducts are 4" piping. you get a tiny air vent similar to a car in various places of the room. quiet, cheaper to install, and not so obtrusive to a home.

Yeah, I guess they could be called ductless A/C. I saw them in Europe, retrofitted into 400 year old stone houses. Seemed to work well.

I saw (online) one where the evaporator and fan unit were concealed in the ceiling. Wouldn't work for my attic though.

These work well:
http://www.mrslim.com/Products/Category.asp?ProductCategoryID=24

check with your local utility - ours has a program (thru BPA, so you probably have it too) where they pay for it & you pay back the loan over 4 years -- the interest? zero!

Unless you are going to chop the hole in the wall yourself, it will cost you as much to put in a window unit. In any case you are at the edge where a 220 window unit would be the way to go, and then you would also need 220.

False economy. Don't get me wrong, as I have a mammoth 220 unit driving the downstairs of my house. They can be real workhorses if you get the right unit.

FYI and thanks to RWebb for the tip, I found this website. Lists tax credit, rebate, and other incentive programs at federal, state, local, and utility level for efficient appliances, building efficiency improvement, and renewable energy systems.

http://www.dsireusa.org/

Looks like a sufficiently efficient split-system A/C would qualify for a 30% federal tax credit and some (need to calculate) state tax credit. Federal credit applies to installation cost as well. Have to do it before 12/31/10.

Split systems are OK..we use them a lot over here even in new build.

Location of the condensor unit is crucial as it affects the output potential.
The other issue is that you'll need to find a condensate outlet for the fan unit in the attic...

Plus you'll need reasonable access to the fan unit to change or clean the in built filter every six months... yeah I know its a pain but otherwise you'll be blowing dust around the room.. great.

I have a 2 zone system in my house, (upstairs/downstairs) but I've been considering installing one of these units in the wall of the master bedroom. I like it cool, practially cold, at night, for sleeping. I would rather just sub-cool the bedroom than the whole downstairs.

These systems are the way most of the former Com-bloc apartments in Eastern Europe are getting A/C. All you have to do is drill a 1" hole. Make sure that the evaporator has a way to drain accumulated moisture. One of the rooms I used in Romania had a system like this, and the drain plugged and my carpet was wet and mildewed in no time. I am seriously allergic to mildew.

I put a $500, two-ton window unit in my garage. I sure wish I'd put that money toward a ductless split unit so it would be quieter. If you put one in, let us know how you like it.

I have 3 different split systems in my flat. I know it is not the ideal situation buy could not do any better due to the room layout.

- 1x1 split in living room
- 1x2 split in master bedroom + studio
- 1x3 split in children bedrooms (2) + dining room

Each of the 3 evaporator is located in each of the 3 terraces. I can control each one of the 6 different room units with a remote control. The outside evaporators are not noisy (helps that mine are the "siesta" model, no kidding).

As was said before, these are quite common outside the US (Europe, Asia). Mine are Daikin brand and are supposed to be very energy efficient.

We've installed a few mini-split systems in home offices and at a nursing home center. We've installed Mr Slim units made by Mitsubishi and have yet to have a callback on any installs.

If you're just looking for something to help cool the attic, have you considered a portable A/C system? You pay for how much noise they make as they cost $250-500. Their downside is they do still require a vent to blow out the heated air (usually through an open window).

is this for the house in portland?

i was at a bbq this weekend and they had A/C :eek:
this was the first private home in seattle that i have ever been to in 31yrs that had A/C

we dont need it up here 99.9% of the year.

good thing the guys from texas are chiming in...

get the insulation taken care of will help in winter too. be easier to get a utility rebate for that up in PacNorWet.

I've looked into the freestanding A/C units. Can't find one big enough (all the calculators say that for 800 sq ft I need at least 15000 BTU). And I'd have to cut a hole in the ceiling/roof for the vent hose, as the available windows are far from where people spend most of their time in the room. I'm not at all ruling that out, though.

I'm getting someone out here to advise and quote on a split-system A/C, also on solar vent fans and anything else that makes sense.

Ted, Portland weather is different from Seattle. I grew up in Seattle for a while (Kirkland actually) and it is cooler, more of a maritime climate. I thought Portland would be the same, but turns out that being 100 miles inland means we have higher high temps and lower low temps than you guys in Seattle. I love Seattle, I'd move there if the opportunity presented.

I'm also going to drill a hole in the ceiling and measure the temp between the rafters as well as visually check on the insulation (hopefully there is some).

I'm dying from heat in the garage with my old noisy 2 ton window unit so I'm about ready to pull the plug on a mini-split system rather than fix the window unit.

I'm looking at the Klimaire brand. The price is right at $1,400 for a 17 SEER 2 ton heat pump unit which is almost half the price of a Mitsubishi unit and I can't find any really bad reviews.

Any thoughts here before I pull out the credit card and log onto Amazon?

you know Mitsubishi has been making AC for a long time both industrial and residential. There is a reason why they are so much more. When It comes to home appliances especially stuff like AC systems, I tend to pay more because they are better built. I would never install a non major brand in a client's home.

I am a big fan of split system if you can make it work with the ducts without hacking up half the house. If not, ductless would be my next choice for your situation in the attic.

You do NOT want too large of an air conditioner.

AC does two things:

1. Removes heat

2. Removes humidity

This second is the most important. If you put a large AC unit on a small house, then your unit will only run very rarely. The problem with that is that this allows humidity to develop, and that leads to MOLD.

A smaller unit that runs all the time is a better idea. You can figure on 15 years from your inside and outside unit, maybe a little less if you are in Florida, where it is going to run year-round and is subject to frequent lightning strikes.

Good luck!

N!

I think 2 ton is about right for my insulated 900 sq ft garage, although the two A/C companies I've had come out to give a quote were leaning toward 2.5 ton.

I like that the Klimaire corporate headquarters are in Miami, Fl. They sound like a young company that strives to build a good product at a good price.

For the $2,800 Mitsubishi system I could just about get a central A/C system but that's really beyond my budget for the garage.

Check and retorque all the connections on the terminal blocks. I've seen a few of them melt and burn up from poor factory connections. Other than that, I haven't seen any problems with them.

The AC in our automobiles is a split system. As a matter of fact the central air system in our homes is a split system. The evaporator and condensor are separated! With central air you are simply ducting the cool air through the house. A split/ductless system you are cooling the one room or area with the evaporator in the room. Coolant flow from condensor to evaporator is same. Air movement within the area is another matter. A felony fan or oscillating fan helps.


I wouldn't hesitate to install a split/ductless system over a window unit.

what color is the roof

anything other then white is hot

we just painted a gray shingle roof white
and the house is a lot cooler
105 in the sun 95 air temps will get 120-130 on a gray roof

yes you will still need better A/C but not as many btu's = $$

We have a ductless split heatpump for about 5 years now, works great.

If I understand correctly you just want to cool the attic... if so the ductless system is the way to go.

But seeing as this thread is several years old you probably have already resolved the problem. :D

Many factors in switching a old heat only system to A/C... long story short cold air needs larger ducts.

Also if I had the luxury of starting from scratch I would go with a package HAVC only because you don't have to worry about leaks at the connections.

I just a quote back on a central AC system and it's $3,375 which is more than I want to spend. One other issue now is that the contractor already contacted the city about pulling a permit :o

Of course I was planning to pull a permit even if I did it myself, but now I REALLY have too :mad:

I think I'll go with a ductless mini-split if I can find a cheap enough electrician to pull the permit.

David,

There are 2 ton package units, already filled with freon, for about $1300. All you have to do is cut 2 holes in the wall, run a duct/diffuser in the ceiling, and a return line to the outside unit. They are not the most efficient units (13 SEER) but you're not going to keep it on all the time.

13 SEER is more than good enough. The vast majority of A/C units today are likely less than 13 SEER. Based on my ammeter, you'd pull less than 10 amps (likely under 8 amps) of current to run a 2 ton unit. 2.2 kw per hour. $0.12/kwh, so 25 cents per hour at most.

Best bet is to keep your upfront costs reasonable, and do a quality install. Ductless would be a great way to go, but a package unit may be cost competitive.

My other thinking on the ductless is how long we live here. If we move, I could take the mini-split to the new garage with minimal effort.

I was able to finally get ahold of the guy who installed our house AC for a song. Hopefully that quote will be within the ballpark for a garage system.

David, on a mini-split, someone will also have to evacuate/charge the system for you, since the evaporator is installed separate from the condenser. On a package unit, you are only running ducting and electrical.

I bought the 2 ton Mitsubishi Mr Slim ductless mini split system. After looking at all the specs I decided the Mitsubishi's better efficiency and quieter evaporator was worth the extra money. With the slow pace I get projects completed it'll probably be a week or so before I can give a product review.

I did look at the package systems like the Bard units we have on our traveling crew shacks but they didn't seem that much quieter than a window unit. Their efficiency isn't very good either.

Are you planning on running it all the time, or just when you want to work? And how big is the garage?

My installer told me Mitsubishi were the best.

My parents just did the ductless split system in their 1919 farmhome and it works GREAT. And yes, you see them everywhere in asia and on the islands

I plan to run it all the time. It's 19 SEER. I'll turn it up during the day and down when I'm hanging out in the garage which has been almost every night and weekends. The garage is about 900 sf and it is insulated.

who wants my Mitsubishi Mr Slim ductless mini split system?

Obviously I have my own system now but what are selling and why?

it is undersized for the room and not really needed after I got my shade trees growed up & put in new windows

shipping to Houston would be a bit high