Best mini-spit heat pump?

[MinnesotaEric]

I'm thinking about popping in my own mini-split heat pump. So far the most efficient I've looked at in the 18,000 pound range is a Mitsubishi rated at 21SEER. It also pumps heat down to -13 degrees F.

I've never done this kind of thing before, but as an auto tech, understand automotive AC systems well. Even so, I need to find out what I need to vac the system down and fill it. My install is pretty straight forward: through a upstairs wall on a walkout basement, with a drop 12 feet down to the dirt. I can pop 20amp 220 service out of the basement to service the mini-spit.

Any advice on the install or suggestions on which mini-spit I should look at? I'm in northern Minnesota and am more interested in electrical efficiency for cooling than electrical efficiency for heating.

 

[man00]

You been over to the HVAC forum? I think Mitsubishi is pretty good..That forum is okay but there are some who will try to poke at you for doing the install yourself.

 

[Tractor Seabee]

If you are a proficient auto AC service tech you should have no problem and have all the equipment you need except maybe silver brazing capability (copper lines). Big difference is the piping system being copper and the components are such as filter/dryer and sight glass. A lot of the small package units have pre-charged refrigerant lines factory charged and insulated. The small cans of refrigerant, you probably use at work, may not match the system charge and can get pretty expensive on your new system. You need to get acquainted at your local HVAC supplier. To buy refrigerant there you will need to show your EPA 608 Refrigerant Handlers certification (probably not required for your auto work).

If I lived in MN I would be more concerned about heating costs than AC costs. Or, maybe equally as you probably have hotter summers and a lot colder summers than we do here in the ocean air conditioned PAC NW.

LOL

Ron, former HVACR Service Technician and still 608 certified.

 

[dstig1]

Commissioning Mini-Split Heat Pumps | JLC Online | Heating

R410 for everything, I believe.

 

[brasco426]

Eric all the new mini splits are R410a. You'll just need a standard vac pump to evacuate the piping. Mitsubishi, Fujitsu, Daikin are all good names. When you hang the indoor unit FYI, I like to take the lines attached to the evap and rotate them out 90* to help make it easier making ref line connections. The lines will end up going through the wall and be outside, flaring will be much easier. You'll see what I'm talking about. Also the indoor unit gets its power from the outdoor unit, Carol Cable works nice, you'll need to verify the amount of conductors you'll need. Also look at Slim Duct to run the lines in, makes the install look much better than running them exposed. Happy Cooling. Donnie

 

[ustmd]

In 2009, I sent 4 months doing this research and came to the same conclusion that Mitsubishi Mr Slim was the best choice--at the time. I have had one installed for my home office since then and love it When the main heat pump gives up the ghost, I cam going to convert the entire house to Mitsuibishi mini-splits.

I found this site to be very helpful:

HVAC-Talk: Heating, Air & Refrigeration Discussion

 

[dadster4]

From the advice I've seen you give and the level of knowledge you have shown on anything mechanical, I don't think you will have any problems installing a mini-split system. The units (always) and lineset sometimes) come precharged. If the lines need to be modified for any reason you will need silvfloss and a flow of nitrogen through the pipe while brazing. The fittings on Mitsubishi and Fujitsu units (very similar good specs) are metric- not SAE, and will require adaptors for your standard gauges. If a precharged lineset is shortened, no adjustment to the charge should be necessary when complete (only about 1/10 oz per foot of 410A). Be sure to use the superheat method to check operating pressures with normal ambient temps, both inside and out, when finished. The proper amount of superheat is usually stamped on the rating plate of the condensing unit. A standard rain downspout can sometimes be used to hide the lineset outdoors (cut out the backside to straddle the lineset). I have installed these units in everything from Water Tower Place in Chicago to horse trailers selling tack while at a horse show.

 

[forgeblast]

we have the Fujitsu halcyon with heat pumps, we have 3 of them off one outside compressor, and its one of the best home improvements we did. That being said I would not do the install my self, because you would void the warranty. I was going to install and then just have them come up to pull the vaccum but no warrenty. They did a great job done in two days even wore booties to keep the house clean. Just something to think about.

 

[C4Ranch]

I went with a 4 zone gree. Like it so far and have kept the cabin warm with outside temps in the teens.

Mitsubishi seems to be the gold standard and priced accordingly. In the end, they pretty much have all the same components IMO. The team (4) that installed mine took entire day to run the line sets and covers. 3 rooms plus an upstairs loft. The lines were custom fit lengths and they made sure the inside units drained correctly before leaving.

My system has a feature that measures temp from the unit or remote which is nice.

 

[TomSeller]

Anyone know what operational savings percentage people are seeing compared to a standard heat pump? I know this depends on many factors, including local climate, but I am curious.

 

[Ed of all trades]

Why not try a pac unit. It has every thing in one place and just needs vented to the outside. I had a guy tell me I could get one for about $800. It is not designed for much duct work and easy to install. They even come charged. Ed

 

[lt190b]

Why not try a pac unit. It has every thing in one place and just needs vented to the outside. I had a guy tell me I could get one for about $800. It is not designed for much duct work and easy to install. They even come charged. Ed

Any details, link, Ed?

 

[GManBart]

I spent months researching them for my pole barn and I'm set on a Mitsubishi. In fact, I'm likely going to add one to the loft in our house as well...pump cold air at the top of the house and ease the load on our central unit (the adjacent great room has a 21ft peak, and no cold air ducts up top). My heating/cooling guy said he was confident I could do the install, then he'd just come evacuate and charge it for me.

 

[RalphVa]

I asked for a Mitsubishi from our local HVAC people about 3 years ago. They said they were getting better deals on Fujitsu. That's what they bid on and what we went with. Assume what you're talking about are ductless units. The Fujitsu is a 27 SEER unit.

Ralph

 

[MinnesotaEric]

I asked for a Mitsubishi from our local HVAC people about 3 years ago. They said they were getting better deals on Fujitsu. That's what they bid on and what we went with. Assume what you're talking about are ductless units. The Fujitsu is a 27 SEER unit.

Ralph

What model?

 

[MinnesotaEric]

If you are a proficient auto AC service tech you should have no problem and have all the equipment you need except maybe silver brazing capability (copper lines). Big difference is the piping system being copper and the components are such as filter/dryer and sight glass. A lot of the small package units have pre-charged refrigerant lines factory charged and insulated. The small cans of refrigerant, you probably use at work, may not match the system charge and can get pretty expensive on your new system. You need to get acquainted at your local HVAC supplier. To buy refrigerant there you will need to show your EPA 608 Refrigerant Handlers certification (probably not required for your auto work).

If I lived in MN I would be more concerned about heating costs than AC costs. Or, maybe equally as you probably have hotter summers and a lot colder summers than we do here in the ocean air conditioned PAC NW.

LOL

Ron, former HVACR Service Technician and still 608 certified.

A mini-split cannot be the primary heating system in MN. I'm mostly concerned about the cooling ability, and how quiet it is. Heating concerns are for backup if the boiler takes a time-out.

 

[joefromga]

I have two Samsung units. Both remote control with digital display and all sorts of features I don't use. I leave them both on 71 and they do the rest. I am friends with an hvac guy who works at trane supply. I got them for half price.

They are no brazed fittings but flared. You should mineral oil those fittings and use proper wrenches to tighten because they will leak if you don't.

I installed them myself on the second floor by building a deck and carrying them up the ladder. The outside units are about 75 lbs. The deck uses chains to hold it up and sort of looks like a moat door.

The hardest part was drilling through the concrete wall on a 24ft ladder. Also make sure the drains are done properly.

They are whisper silent inside and out. You can't hear the outside unit even on the ladder standing right in front of them. They have special shaped fans with out of phase balancing or something to make all sounds go away.

About 2 years now or 3. I've been very satisfied and I'm in South coastal GA where it's hotter than anywhere else. Always 71 in my two rooms. Heat works well too but we rarely need it.

 

[TnAndy]

Why not try a pac unit. It has every thing in one place and just needs vented to the outside. I had a guy tell me I could get one for about $800. It is not designed for much duct work and easy to install. They even come charged. Ed

I don't like them due to the noise factor. Anytime you have a package unit, like a window AC, or one of those cheap motel units, the noise is loud. The indoor units of mini splits are generally whisper quiet. I have to look at the little LED on mine to even tell if it's on when on low.

I did the installs on both my mini-split units.....an 18kBTU about 10 years ago ( I think it's mid-teens rated), and a 12kBTU for the master bedroom couple years ago (rated 23 if I recall)...Both Mitsubishi. Both have done well, no service issues. I mounted the units, ran the lines, then paid a HVAC guy to come vacuum done the lines, turn the pre-charged gas loose, and start up the units. $100 in each case, saving me from rounding up a vac pump and set of gauges. For lines, you buy refrigeration copper of the recommended size, and flare the ends. I think mine you could go 50' was the recommended max length for the amount of gas in the unit....neither of mine was close to that long.

 

[RalphVa]

What model?

Bad memory. It's 18 SEER. Model # is AOU18RLXFZ connected to a 12k BTU and 7k BTU indoor units.

Ralph

 

[RalphVa]

I mainly just use ours (in basement) for additional heating in winter. Have one indoor unit right above my desk here and another in the den in another corner of the basement, blowing onto the couch there. Using them occasionally with just fan on in indoor units, mainly here at my desk where I don't have an overhead fan. The big heat pump services both the basement and the 1st floor of the house, and basement cannot be zoned out. In winter, one can freeze in the basement unless you want to run the rest at well above 70. When I was sick with CHF, I was using little direct electric heaters to keep myself warm before we put this Fujitsu system in.

It's totally noiseless, both indoor and outdoor units. I remember walking by similar units at offices in Japan. Hardly any noise. No backup heating coils in these units.

Think they can run up to around 7 indoor units. Could have gone with them instead of replacing the upstairs heat pump that we did recently, but it would have been a much more involved job, as they have to drill some holes through the brick where each indoor unit goes to run the refrigerant lines (R410a). Would be a challenge, too, where to run the lines, etc. Probably would run them around inside the eaves of the house and just drop down to each indoor unit. Would be a lot of refrigerant lines.

You DO NOT want one of these indoor units discharging right above where you mainly sit or lie when it's operating in heating mode, as it often goes for a rather long period just blowing semi-warm air before the compressor kicks in again to make it truly warm. Okay in AC or fan mode though, as that's what you want.

Ralph