Let's discuss Ductless Mini Split . . .

. . . And other HVAC alternatives to add to an existing residential property.

What are the pros & cons of the system?

Are they more efficient than an A/C system that requires duct work?

 

Are there other alternatives to consider?

 

Mitsubishi is the "innovator" of the inverter compressor and the first to bring it to market, which has been out for a while now. Other manufacturers are starting to follow suit and are playing catch up. That means it is a true variable rate compressor vs. a Hi/Lo speed. Depending on the system type and size, they can cost less to operate than a flood light. They are designed to run all the time but they run at a very low speed and you don't even notice they are on. Daiken is another of the top manufacturers.

Pros and cons depend on the application. If you are adding a sun room, screened porch, finishing a basement or conditioning a garage they are great. I have done a whole house with them. It was an older house and they wanted them instead of conventional ductwork. It wasn't practical but they were happy.

Only con to them is you have an air handler hanging on the wall. Most people think it will be an eye sore and don't want it till after it is installed and running and they realize how great they are. Mitsubishi also makes ducted mini splits that use conventional duct work. It all depends on what you are trying to do to determine if there are other alternatives.

 

Could not be happier with my Mitsu system. They are freaking fantastic. I've said it before that if I were building a new house these would be implemented in as many rooms as I could get them in a still make placing the eternal units not an eye sore.

 

I have an LG system. It works awesome!!

It will cool a 300 sf room in less than 10 minutes.

 

If you don't want it on the wall, Panasonic makes a ceiling recessed model also.

Many pros, few cons. The only con I've found is that the blower wheel will require cleaning every year or two and can be a pain.

 

OK thanks for this thread. In the new house I have TWO garages that are connected by a door in the middle. Each garage is 950 sqft I want to be able to cool one of the 950's and leave the other one warm, it's just storage now, but eventually I will make it a man cave.

Does anyone have any recommendations on models? I have heard that you can buy one outside unit and then have two internals one for each room.

how energy efficient are they compared to a standard unit?

 

Following this thread while doing my own research. I've seen that there are a lot of pros and not many cons for this system.

This would be for a whole house. I was attempting to alleviate the ductwork too. Why isnt it practical?

 

Cost

Just spec'd an 18k btuh heat pump model for a friend's storefront, came in ~$2500.

Multiply that by the number of units you'd need to achieve your whole house heat/cool needs, and the impracticality soon becomes evident.

 

I'm selling my current property and looking for another. The potential property has oil heat that I want to convert to gas. It needs central air and I was thinking that I could go without the duct work to save some money and local power company is offering rebates on theductless system.



On a side note, whats a rough estimate on converting from oil heat to gas? The property also has an electric stove which I want converted to gas.

 

So overall it would be less expensive to go with conventional central air (duct work) vs. going with the ductless system?

 

All depends. Mini-splits are great for retrofits where your only other option would be resistive electric heat and window unit AC.

Gas is still the least expensive heat source. Between the units cost and the btu cost, a 90+% efficiency with ducting will overall be more efficient.

 

You can have as many as four indoor fan modules connected to one condenser. The cost for the multi-head units is usually the sticking point, but in my opinion, the benefits outweigh the cost.

Ductless splits are generally far more efficient than conventional split systems. 17-20 SEER is not uncommon, but that's only part of the story. The systems' ability to modulate it's output means that much of your operating time is low-load and thus low consumption.

 

Does that come mainly through a quality installation? The ductless system advertises 30% inefficiency with most duct work systems.

 

Ductless splits vs conventional splits

Whats the difference?

 

That's the efficiency rating of the furnace, namely a direct vent vs a naturally vented.

Caveat: this is all based on the heating/cooling needs of my local area, different climates will have different ideal designs. :up:

 

conventional split means condenser outside, FAU inside with duct running from the FAU plenum throughout the house. easy to install when the house is just framing. not easy to add duct to an existing house, unless you have a nice size attic and size the unit for all flex.

ductless split means the internal unit has no duct. it hangs on a wall. it will cool an individual room easy, but, if you put it in your master bedroom for instance, and closed the door, the space outside the master will be warm since you are only cooling the room the unit is in.

as mentioned, you can connect multiple ductless splits to a single larger condenser if you go mitsu/lg/daikin, but, you need to have the lines sized properly by the vendor. location of tees, runout after tees, line size beyond tees change after each branch depending on location of condenser, height of the splits (ie, condenser on ground outside, splits on second story)

if you are trying to cool an entire existing house, that has ductwork ran, it is going to be more economical to demo the existing furnace, put in a furnace/heat pump and coil and condenser...

hope that isnt confusing.

for Critter- trying to cool one garage but not the other, that is the perfect application for a ductless mini split.

 

I figured that much.

 

Duct losses are not a major issue in applications where the ductwork is in the conditioned space. That statement is probably true when applied to attic systems.

 

very nice stuff.. expensive, but quality & extremely efficient. We install them quite often.

ductwork is your biggest difference & if designed and installed correctly will work very well.