Since about 2005 I have been following the ductless mini split system market, although I’ve heard that they have been around since the mid-60s. I must say over the past several years, Mini’s have become the rage—I continually hear how popular these systems have become. As far as what brand is the best, in the interest of not offending any of the manufacturers I will play it safe and say do the research. A/C mini splits also seems to be growing into a must have item. I recently asked a few HVAC contractors how much of their business A/C mini split systems account for and the answer I get is generally between 85% to 90% of their residential business.
I then questioned, what makes these units so popular, and answer is it’s simply the ease of the installation, cost and rebates available. But like any heating or cooling job, the main concern is the proper sizing of the units for each room and the electric source availability. Remember, the wrong size unit can produce short cycling that will lead to inefficiency and higher energy costs.
It’s also easier to zone any number of rooms and works well when adding an addition or a home equipped with hydronic heating. Another important piece of information I learned, was that more than one of these wall heads can be connected to one condenser. However my first thought was if the one condenser should fail wouldn’t all the units fail to function? I also asked a contractor how long does it take to install a unit and I was told the average job takes about four hours from start to finish, depending of course on the size of the job. I would say that compared to running a mass of metal and flex duct for one or two floors the Mini is a good choice.
Keep in mind that before the mini split systems, all AC traveled through the conventional metal trunks and the property owners were very happy on a 90 degree day. However, what we have learned is that many of these old systems chewed energy dollars due to the leaks found in the duct work. Today, thankfully, many communities require a duct pressure test on all new duct systems before the inspector will sign off on the job.
I’m also told that some contractors are offering home owners a mini split as the main source of both heating and cooling. Another sales suggestion is that a heat pump [mini split] system as a way to reduce the cost of heating a house supplied with home heating oil.
Personally I have a problem with this idea, because, as we know, heat pumps have a temperature limit during the cold winters that we often experience. Take into account that in 2015 the New England area experienced temperatures of between 4 and 9 degrees below zero and I would bet that if the heat source was a heat pump mini split, there may have been a problem meeting the normal desired temperatures.
What about service? I hope that the installers remind their customer that mini spit systems require an annual service to both the interior and outside unit in order for them to maintain their level of efficiency.
On another note, keep in mind that there are now console floor mounted mini splits available.
Selecting the proper Seasonal Energy Efficiency Rating ratings–this depends on where you are doing your work. For example, if I were a contractor in Florida, the higher the better, but if I were installing in New England 15- 17 would be normal.
Another question I’m asked is what’s the life expectancy of a mini split? I reached out to my contractor friends and they told me that other than a factory issue and with proper servicing the home owner can get 10-15 years of dependable service. They did mention that part availability can be an issue when offering service and this is due from having so many different makes and models that often come from outside of the United States.