Split system HVAC advice

afterburnt

I think this is the way to go instead of a central system. Does anyone have one, if so any tips on what to look for? I am pretty sure I will have to use the ugly wall monts, I pretty much don't have an attic.

msg

I've only got small space experience with these; are they available for whole house type installations with multiple units running off of one condenser? If not, wouldn't you be looking at multiple units for each space?

mrbiron

I put 500 of them in a project we did 2 years ago...
Yes, multiple heads can be run off the same condensing unit.
For us, only bedrooms and main living room received a head unit.

More info is needed...

Do you have a basement? How big is the attic? How big is the house?

polrbehr

I installed one when I finished my garage into a man-cave.

The one I bought is made by Air-Con, but IIRC most of them have compressors made by Toshiba? It's 9000 BTU, has a SEER of 21.5, and does both heat and A/C. The room it's located in is 14' x 22', but total sq ft is about 450. I've had this for a little more than 4 years, it works as it should, and it's pretty quiet too. It cost me $300 to have it installed, but I ran the 20A circuit and helped the guy put it in so YMMV.

The only thing I would do different is I would have gone for the model with internal heat; when temps fall below 15F, the heat does not work so well. But I've since added an electric baseboard so that's not an issue now.

afterburnt

@mrbiron 1800 sq ft 3 bedroom split level kind of thing with vitually no attic and stupid high ceilings in most rooms with like vertical skylights up top in some of the rooms. Forced air semi central heating for supplemental/backup heating. It's not ducted into two of the bedrooms, the dumbass that built this thing had electric wall heaters in the non ducted rooms. They have been removed and I was tricked into thinking that the were functional ducts because the seller put big registers over the empty spaces where the heaters were. Oh the existing cooling is a swamp cooler which is ok until monsoon season arrives like damn near all summer. It is on the roof and I am thinking of replacing it with some kind of whole house fan. Generally more heating than cooling needed in this part of AZ due to the elevation. It snows now and then in the winter.

obieone

Check out hvactalk.com, for feedback on which brand is best.

afterburnt

obieone wrote: »

Check out hvactalk.com, for feedback on which brand is best.

Thanks but it is:hvac-talk.com. If you don't put the dash it tries to add a browser extension or something.

rpf65

The best brand, of what we refer to as mini-splits is Mitzubishi. No contest, wouldn't recommend anything else.

Their warranties are some of the best out there. Installed and registered by a diamond, Mitzubishi authorized and trained, 12 years on the parts. Non diamond install, 5 years parts except compressor which is 7.

Lots of variables go into the multi-head units, the biggie, and usually the one that gets messed up is total refrigerant line length. So it pays to spend a little extra should you decide on the Mitzubishi for a diamond contractor. Find those guys in your area on the Mitzubishicomfort web site.

The heat pumps will heat fairly well down to about 20 F.

Myself and a couple other techs have spent about 2 years fixing mistakes from a contractor who installed one. Not diamond, so by the time they called us, warranties were about done. Not setting units and the branch box in accessible areas added more for sheet rock repairs and access modifications.

Just throwing this out there. Carrier, under their Carrier and Bryant makes a 5 speed condenser for their full size split systems. They're rated somewhere around 20+ seer on pretty much everything up to 5 tons. May be a better, less costly solution, depending on house size and how many rooms need conditioned.

Anyway, I've been to many home in 100+ weather that have those units. It's a rare thing to see them running in high speed. As with the mini-splits, the install is critical. If that isn't right, you won't get the performance or life span that properly installed equipment will give you.

afterburnt

@rpf65 How bout Fujitsu, someone recommended that brand?

rpf65

Also a good brand. Mitzubishi has better parts support and a slightly better warranty.

Fujitsu makes a quality product, not as many sold, so sometimes parts can take a while to get in. At least my experience in the Austin area.

BlueBirdMusic

I don't have one but I agree Mitzubishi has been the leader in the splits.

obieone

Yeah, Mitsubishi pretty much pioneered this style, they're call "city multi splits"
There are others that do the same thing.
If you register at 'hvactalk.com', you can post a thread, looking for guidance on which brand is best.

http://hvac-talk.com/vbb/forumdisplay.php?1-AOP-Residential-HVAC

I work in commercial/ industrial, so I would be less than useless in this endeavor.

Good luck, and make sure to do some due diligence with regards to the install co.
Low bid is low for a reason

obieone

Yeah, Mitsubishi pretty much pioneered this style, they're call "city multi splits"
There are others that do the same thing.
If you register at 'hvactalk.com', you can post a thread, looking for guidance on which brand is best.

http://hvac-talk.com/vbb/forumdisplay.php?1-AOP-Residential-HVAC

I work in commercial/ industrial, so I would be less than useless in this endeavor.

Good luck, and make sure to do some due diligence with regards to the install co.
Low bid is low for a reason

polrbehr

obieone wrote: »

Yeah, Mitsubishi pretty much pioneered this style, they're call "city multi splits"
There are others that do the same thing.

Just to offer a different experience, there is a City Multi on one of the outer buildings at work. And even though it's 10+ years old, the fan is very noisy (a constant 62db drone), and during heating cycles sometimes makes loud crashing sounds like someone dropped a block of ice on the roof.
Maybe they manufacturer them better these days, but I stayed away from Mitsu for this reason when I was researching.

mrbigbluelight

Sounds like worn/loose rubber compressor mounts. Easy fix.

I've only read of the Mitsubishi units (good) but I would suggest from hands-on experience NOT to buy a Daiken unit.
No matter how good the install is on those units, the parts/design leaves quite a bit to be desired.

afterburnt

Is anyone familliar with Daikin?

mrbiron

The job where we put in hundreds of them were Haier.
They are cheap junk unless something has changed in the last 3 years?

rpf65

afterburnt wrote: »

Is anyone familliar with Daikin?

Stay away from them.

Dennis Gardner

Funny story on split system....Forced air heater in the basement and central AC unit in the attic added at different times over the years.......my wife came home on a smoldering summer day when our youngest son was about 7 years old and found both AC and heater running full force against each other. He claimed he was too cold so he turned up the heater. Made total sense to him as that is simply what he did all winter long when he got cold. Training fail on us parents.

afterburnt

Question: Would a conventional ducted system be worth looking at, most of the house is already ducted for heat although they are all floor vents, which is probably the worst place for AC? Oh and the return is downstairs so I figure it will just suck all of the cool air off of the floors and pretty much defeat the purpose, am I right or am I wrong?

Dennis Gardner

The vents can be anywhere and a combo setup is usually a compromise anyway. An AC works best with vents above and returns down low. A heater works best with vents down low and returns in the ceiling.

lightman1

This^^^

Fargin Thermal Damnanics!

afterburnt

Dennis Gardner wrote: »

The vents can be anywhere and a combo setup is usually a compromise anyway. An AC works best with vents above and returns down low. A heater works best with vents down low and returns in the ceiling.

I was kind of thinking you would want to suck the hot air up high for AC and the cold air down low for heat, no? I agree with your description of the discharge configuration that you describe.

vmaxer

lightman1 wrote: »

This^^^

Fargin Thermal Damnanics!

Come on @lightman1 - just pick one and run it backards every other seasun.

rpf65

It doesn't really matter where the supply vents are located. In the southern locales they are usually on ceilings or high on the wall, because we care about hot temperatures more so than cold. Close to 8 months of a/c versus 8 weeks of outdoor temperatures below 40 F.

Just the opposite in say Boston, for example. They have 8 weeks above 80 F, and 8 months below 40 F, so the cold is more important. There vents are ran on floors, or somewhere low in the room, depending on the heat type.

As long as the equipment is sized, and installed correctly, it will heat and cool your home to a comfortable level. Even at 105 outside, we can cool homes to the 70 degree range with floor vents in the home.

Real simple, if your duct work is good, not leaking and sized correctly, return air is adequate and again not leaking, and the equipment is installed correctly, you would need a 3 ton system in Austin Texas. Have a warm or cold, that is what air balancing is for.

My personal advice is to look into both a full sized split system, as well as the mini splits. Don't know why f you have all electric, natural gas, or propane, but that also matters.

Natural gas, two stage furnace, with a single speed condenser is what I usually recommend. All electric, single stage heat pump, with variable speed fan coil. Propane, duel fuel, single stage heat pump with a two stage furnace.

if money is not an issue, there are, what are referred to as, variable speed condensers out there. They're actually 5 speeds, and their seer rating is right up there with the mini splits.

Sealing in duct work, air balancing, and top of the line variable speed full system will probably cost a little less than installing mini splits in a 6 room house. Don't forget about the bathroom, if you want to keep the wife happy. The master bath, in the mini split world is one more room.

Dennis Gardner

afterburnt wrote: »

Dennis Gardner wrote: »

The vents can be anywhere and a combo setup is usually a compromise anyway. An AC works best with vents above and returns down low. A heater works best with vents down low and returns in the ceiling.

I was kind of thinking you would want to suck the hot air up high for AC and the cold air down low for heat, no? I agree with your description of the discharge configuration that you describe.

In practical installations the returns get put wherever is most practical and isn't as important as the thermal flow of the incoming air. In homes I rarely see ceiling returns, in businesses the ceiling is done more often.

afterburnt

Thank yooz for all of the info, now I can drive the guy crazy when he comes out to give me a quote.

afterburnt

Mitsubishi 5 head system $24,000!

ken brydson

afterburnt wrote: »

Mitsubishi 5 head system $24,000!

Come with KY?

afterburnt

ken brydson wrote: »

afterburnt wrote: »

Mitsubishi 5 head system $24,000!

Come with KY?

It had better, and a happy ending!

rpf65

Sounds like you have about 7 rooms to condition.

Just a guess, but you could probably get a 16 seer System, with all new duct work for about half that price.

Move up to Carrier's inverter series for about 1500 more. That thing is 21 seer for a 3 ton model. That's really close to the Mitsubishi efficiency rating.

Those condensers, the outside unit, use very similar technology as the Mitsubishi condensers. Inverter compressors and a dc fan motor. The Mitsubishi gets a higher seer rating mainly due to the inside units.

The little dc motors are much more efficient than a 1/4 hp, ac used on a full size air handler or gas furnace. Pretty sure the 3 tons use a 1/4 horse motor. Anyway, that's worth about 1 1/2 or 2 seers.

Still think you should get some bids on split systems. I can give you a crash course on actually understanding what that rating means to the average pocket book. Take about 2 paragraphs.