ductless mini split heating and cooling

[JoeWras]

With a variable-speed compressor, raising the temperature setting up a degree or two will cause the compressor to go into a slower speed and reduce its cooling capacity. I wonder if this helps.

I can also dial down the blower speed of the indoor unit. This should slow down the airflow to increase the condensation of moisture for dehumidification.

The above said, I often crank the blower speed on high, because it's so dry here, and I also want a strong air circulation to achieve an even temperature inside the home.

It was a smart unit and had all the fancy stuff. The problem was the installer just defaulted to the largest size because "that's what he always did since it works."

It didn't work.

This was over a decade ago when mini-splits were first coming online in the US. The installer was incompetent. When we got it replaced last year, the new installer could not believe how oversized it was.

 

[NW-Bound]

It was a smart unit and had all the fancy stuff. The problem was the installer just defaulted to the largest size because "that's what he always did since it works."

It didn't work.

This was over a decade ago when mini-splits were first coming online in the US. The installer was incompetent. When we got it replaced last year, the new installer could not believe how oversized it was.

Was it an variable-speed inverter unit though?

When I replaced my central 5-ton AC which was perhaps 15 years ago, I was looking into spending more to get a fancier unit. Back then, there were no variable speed units, only dual-speed ones, which claimed to be more efficient. It turned out that they had two compressors in there, a large and a small one. And they were not reliable, so I went with a conventional unit.

 

[JP.mpls]

We had Mitsubishi mini-splits installed in our Cape renovation. Didn't want the ducts in my basement and too hard to put behind the attic knee wall.

They absolutely dehumidify the air.

We love them. They are much quieter than my central air was in my last 2 homes. I also really like that I can put my bedroom into a deep freeze at night without affecting the rest of the family.

We have found them much less expensive than any other AC. We don't really use the heat because we have gas hot water heat through a Navian which is super efficient. But on a really cold NY winter day, I will use it briefly after I've been out to take the chill out of the room as the heat comes up.

I will say if you go mini-split it is very important the installer is properly trained. Proper sizing is not as easy as you may think. We used a Mitsubishi Diamond Contractor which I believe ups our warranty to 12 years. He was also much less expensive than the other companies who quoted me Daikon units.


We also got a $750 rebate which was nice.

Laura,
I just had one of these installed in my upstairs bedroom. I'm hoping it works out good.
I've dealt with a window unit for forty years. It should be a vast improvement.
Take care.
JP

 

[euro]

I installed a Mr Cool 24K mini-split in our 1456 sq/ft house last summer. I originally installed it because we didn't have any kind of air conditioning for hot weather. However, I only used it in AC mode for one day before switching to heat mode.

We have individual wall mount electric heaters in each room, so we don't have any existing duct work. I only expected to use the mini-split as supplemental heat to our wall heaters, but was surprised we could heat our entire house with it all winter. When temps got down in the 20's or 30's outside the wall heater in our master bedroom (furthest from the mini-split) would sometimes come on, but otherwise the mini-split handled the entire house.

We also noticed a minor reduction in our electric bill too. It wasn't a drastic change, but certainly less than we had been using. It's also quieter than our wall heaters with fewer drafts and temperature swings.

Once temps get below freezing outside the outside unit has to run a defrost cycle periodically, but otherwise it still heated fine in 25 degree weather.

The mini-split is now our primary heat source, supplemented with our original electric wall heaters if needed, with a wood stove as backup when the power goes out.

I installed one too a few months ago in our small log cabin in the NC mountains. Took less than a day to complete. It works great! I especially love that I can turn the system on/off remotely, so I can get a head-start cooling or heating the cabin when I start driving up to the cabin. We used to heat/cool with a through-the-wall type system that was very loud. The mini-split is very quiet. So far, well worth the expense!

 

[folivier]

Euro, please follow up on your Mr. Cool. Especially for heating when the temps are low, like below freezing. I have baseboard electric heating at our cabin and wood stove and thinking of adding a mini split for heating. Cooling is not needed here but heat is in the early fall through late spring. And electricity is pretty expensive. Thankfully firewood is free just need to cut and split it.

 

[euro]

Euro, please follow up on your Mr. Cool. Especially for heating when the temps are low, like below freezing. I have baseboard electric heating at our cabin and wood stove and thinking of adding a mini split for heating. Cooling is not needed here but heat is in the early fall through late spring. And electricity is pretty expensive. Thankfully firewood is free just need to cut and split it.

Will do an update when I have some deep-freeze experience. It usually doesn't get REALLY cold before January (even then, we rarely get into single digits or even teens for extended periods).

 

[mountainsoft]

I installed one too a few months ago in our small log cabin in the NC mountains. Took less than a day to complete. It works great! I especially love that I can turn the system on/off remotely, so I can get a head-start cooling or heating the cabin when I start driving up to the cabin. We used to heat/cool with a through-the-wall type system that was very loud. The mini-split is very quiet. So far, well worth the expense!

Yeah, I've been quite happy with ours. We had another long hot summer this year and I barely noticed with the mini-split AC running in the house.

My only gripe is the remote control/wall thermostat. Our indoor unit is mounted high up on the wall in our vaulted kitchen/dining area. It's a lot hotter up there than the rest of the room, so the default temperature control is way off when measuring the room temperature up there. The rest of the room is too hot or too cold when measured at the indoor unit. I can solve this by using the "Follow Me" feature on the remote, which measures the temp where the remote is. That's fine, except the IR signal from the remote is weak which means the only place I can place it is on the half wall next to our kitchen. It's prone to getting bumped there, and frequently gets blocked by things on the kitchen counter.

I like the wall thermostat better, it has a much stronger IR signal and I can mount it on the wall next to our other thermostat. Unfortunately, even though it has a follow-me feature in the settings, it doesn't appear to work. It still measures the temp up at the indoor unit.

I tried ordering a Ceilo thermostat, which worked OK, but the black color really stood out against our white walls, and it required a power source to operate. There's no outlet where I want the thermostat, so I would have had to install something. There were a couple other issues I can't remember, but I ended up returning it.

All three controllers lose your settings any time you switch modes or turn the unit on and off. For example, I have to reenable follow-me any time I switch to heating mode, or if I change batteries. Kind of annoying, and not exactly wife friendly.

Other than the controller situation, we have been very happy with the Mr Cool mini split for both heating and cooling.

 

[explanade]

Stayed at a B&B in Venice a couple of weeks ago.

The mini-split worked well because it was hot.

But it dropped condensate constantly.

The mini split was installed over a door so once the room was vacated, it would drip onto the floor instead of the little pail they gave me.

Never seen a problem with the mini split in any other places. It cools the room much faster and more reliably than central air systems.

 

[euro]

Stayed at a B&B in Venice a couple of weeks ago.

The mini-split worked well because it was hot.

But it dropped condensate constantly.

The mini split was installed over a door so once the room was vacated, it would drip onto the floor instead of the little pail they gave me.

Never seen a problem with the mini split in any other places. It cools the room much faster and more reliably than central air systems.

Maybe the line was clogged? Condensate should not drip from the indoor unit - normally there is a drain line and it drips outside.

 

[Dash man]

Maybe the line was clogged? Condensate should not drip from the indoor unit - normally there is a drain line and it drips outside.

We just had a mini split system installed at our beach house. The use a condensation pump to push the drip outside. It does sound like a clogged line.

 

[explanade]

I wonder about installing a mini split in the upstairs main bedroom, which has a weak output from the central air because the bedroom is way up there and maybe the HVAC isn't strong enough to push enough air.

But they say the mini split doesn't have to be installed on a outside wall yet they must run this drain line to the outside somehow, like though internal walls or something?

And how do they deal with it being on an upper floor, they have to run the drain line to the ground or let it drip down from the upper floor?

 

[Dash man]

I wonder about installing a mini split in the upstairs main bedroom, which has a weak output from the central air because the bedroom is way up there and maybe the HVAC isn't strong enough to push enough air.

But they say the mini split doesn't have to be installed on a outside wall yet they must run this drain line to the outside somehow, like though internal walls or something?

And how do they deal with it being on an upper floor, they have to run the drain line to the ground or let it drip down from the upper floor?

A compressor is set on the ground or hung on the outside wall with connections to the inside unit. They would just run any lines up the side it your home and cover it to make it less noticeable.

 

[Old Microbiologist]

We have 3 mini-split systems in our house. Two are 2.6kw and the larger one for use in the large main floor is 5kw. The latter had dripping problems as the installer put a 90 degree bend in the drain pipe which sometimes provided enough pressure to block the drain. I re-routed the drain line so it was a 30 degree bend and a longer down run and it now works fine. Sadly, it had been dripping unseen on our nice tile floors and my wife skipped and broke her foot hence why I needed to fix it.

I have had them for 10 years now and no real issues. They heat gently and have worked fine down as low as -10C which is about as low as it ever gets here. Our main system is a gas condensing boiler (now mandated by the EU) which is fairly efficient and works well. However, our gas prices have gone up 700% this month so I have that turned off for heating. We have had a snap cold for the past 2 weeks hanging near zero in the morning and the splits were enough plus we have a very large solid German-style fireplace that gets very warm but doesn't effectively heat the room. I need to put a small fan to move the air around it and I think that is sufficient to heat the entire floor of roughly 120 sq meters. If not I can turn on the split for added heat. Our electricity has "only" gone up 100% from roughly 10 cents a kwh to 20 cents so actually not horrible. Hungary is more or less self-sufficient for electricity but is being mandated to give 20% of gas to the EU to make up for those idiot countries that refuse to buy Russian gas. They are still buying it but instead now from Hungary or Serbia. The government has raised the price on "rich" people (those above the mean average annual usage) to make up for the subsidies for the poor and the price cap on gasoline and diesel. So, we just simply stopped using gas until this gets sorted out. Hungary gets it gas via a long-term contract with Gazprom through the Turk Stream that now ends in Hungary. It used to end in Serbia but we have become friends with them so added to the pipeline. The long-term contract rate is still secret but it is rumored to be even less than it was before so probably under $200 per million cu meters (way less than the $3,00 spot market price).

Anyway, this winter looks to be something rough so I will find out firsthand how well the mini-split systems work when it gets cold and no gas heating. We have already dropped the temps to 19 degrees and put on socks and sweaters. I am used to it now so it isn't all that bad.

 

[Bamaman]

My vacation home has 3 bedrooms and a bathroom up stairs. Downstairs is a large kitchen living room and a utility room/bath.

I would have liked to have put a mini-split in when I had to replace my heat pump, but I had all the sheet metal already installed and a new heat pump was cheaper than adding one mini split and a second mini split with 3 head units.
For those that just have a large room: I once had a 16' x 32' den with a PTAC unit like those used in hotels. I'd cut it on when I got home from work, and it'd cool a hot room to comfortable in 10 minutes. And it was very efficient since we only ran it when we were in the room. Any individual can cut a hole in the wall, install the housing in the hole and slip the PTAC unit in. They're not nearly as expensive to buy or install as a mini-split.

 

[Chuckanut]

I remember the hotel ACs as usually being very noisy with very annoying vibration noises. Splits should be much quieter. Right?

 

[REWahoo]

PTAC units aren’t as quiet as splits due to fan noise but the better quality units don’t vibrate and they do cool quickly. We have a heat pump PTAC in the playroom and it has worked great for more than 20 years.

 

[JP.mpls]

I remember the hotel ACs as usually being very noisy with very annoying vibration noises. Splits should be much quieter. Right?

Chuck,
The one in my cabin is amazingly quiet. Even the compressor/condenser? Unit outside is quiet.
I just purchased another system for my upstairs bedrooms in my old city home.
JP

 

[skyking1]

Ours are sitting outside on some concrete pads and are not at all audible inside the house.
They are really quiet outside too.

 

[indiajust]

Rather dramatic improvements. Just moved into renovation project in historic mill building. All minisplits, they pump the condensate from cooling up to the roof. New refrigerant good down to -24F. Plumbing hidden in walls. Excellent in space constrained, esthetics, or system programmability. Entire building is learning to manage itself via some kind of shared software. Totally intriguing.

 

[Samsung4321]

They are a reasonable option if you want to add heat or A/C and you don't already have ducts in the house or room. If you already have ducts, stick to a conventional system. Also, my experience is that these mini-splits, even the ones rated to -15 degrees F work better as air conditioners than they do as heaters when it gets extremely cold.

Most of the reason for seemingly poor cool-cold performance is due to room temperature stratification - warm near ceiling, cool near feet. Especially where indoor unit is mounted high which is the norm in warmer climates.

The solution, other than increased insulation, is cheap, easy, simple and effective:

. A fan on the floor pointed up to lift the cool air near the floor and mix it better with the warm air near the ceiling.

Saves money as the control temperature can be lowered while the temperature at foot is increased.

 

[Chuckanut]

What's the difference between a 'normal' ductless system and a mini-split. Just the capacity and need for a 240 volt power source?

I ask because I am looking at getting a ductless system installed in my home. I have no AC but the need for it seems to be increasing. Whether that is global warming or me getting older, I don't know. Probably some combination. I also need more heating power as the base board heaters have never been able to keep up when temperatures drop below 32 degrees. It can literally take 6+ hours to heat the house from 60 to 68 degrees when the temps drop into the 20's. Needless to say, I keep the thermostat turned up at night, when the outside temperature drops very low.

Oh, I would keep the base board heaters as installed. Cold is a bigger threat in my area than heat. I might as well have a backup.

 

[lauradrops]

What's the difference between a 'normal' ductless system and a mini-split. Just the capacity and need for a 240 volt power source?

I ask because I am looking at getting a ductless system installed in my home. I have no AC but the need for it seems to be increasing. Whether that is global warming or me getting older, I don't know. Probably some combination. I also need more heating power as the base board heaters have never been able to keep up when temperatures drop below 32 degrees. It can literally take 6+ hours to heat the house from 60 to 68 degrees when the temps drop into the 20's. Needless to say, I keep the thermostat turned up at night, when the outside temperature drops very low.

Oh, I would keep the base board heaters as installed. Cold is a bigger threat in my area than heat. I might as well have a backup.

As far as I know they are the same thing. I had them installed in my current home and still use my gas heat but like having it for back up heat if ever needed. I did use the ductless heat in my daughter's room last week because she was sick with fever and chills, and she felt wonderful with it at 72 degrees which would have been way to hot for the rest of us in the house. So that was nice.
I am currently in my third house, and my last 2 had central air. I can easily say that I much prefer the ductless even though they have the indoor unit on the wall. They are way more efficient, dead quiet and I can customize the temperatures to everyone's liking. I used to hate hearing the central air compressor kicking on and off like a jet.

 

[Chuckanut]

Does anybody have a ductless system with the main outside unit hung on the an exterior house wall? If so, are there any problems with vibration and noise?

I ask this because I don't really have a good place on the ground to put the exterior unit.

 

[finnski1]

Does anybody have a ductless system with the main outside unit hung on the an exterior house wall? If so, are there any problems with vibration and noise?

I ask this because I don't really have a good place on the ground to put the exterior unit.

Mounted mine directly on the house exterior. Didn't want it on the ground. No issues at all.
Hangs on brackets and the mounts have rubber vibration isolation feet.

 

[lauradrops]

Mounted mine directly on the house exterior. Didn't want it on the ground. No issues at all.
Hangs on brackets and the mounts have rubber vibration isolation feet.

Same here. I am amazed by how quiet it is even standing right next to it.