External unit of a ductless mini-split

Sometimes you can do all this plus more and STILL have comfort issues.  It may never get comfortable or it’s freezing one minute and then too hot a few minutes later.

If you have given up and are ready to throw in the towel, then take another approach. You may  benefit from a Ductless Mini-Split Air Conditioner.  What’s a Mini-Split?  The best description is a  window air conditioner WITHOUT the window. If you have ever traveled to the Caribbean or the Orient you see them EVERWHERE.  The most common brands are Mitsubishi Mr. Slim, Sanyo, Daikin, LG, and Fujitsu just to name a few.

Ductwork is a very western idea. By using a ductless mini-split, you can easily bring more air conditioning (heat removal) to either an interior space or an exterior room without a noisy window unit.

Diagram of how a mini-split ductless system works

An air conditioner basically has three parts: 1) Compressor 2) Fan 3) Coil. A window air conditioning unit has all three together.  In a ductless air conditioner, the compressor is OUTSIDE and the fan and coil are INSIDE usually connected by a ¼” or 3/8” copper tubing.  The beauty it that the inside unit can be as far as 100 feet from the outside condenser.

Installation is pretty simple since there is usually NO electrical requirements for the inside fan coil.  Power to the inside unit is brought from the outside unit along with the refrigerant lines.  This means that basically you can drill a hole in a wall, run a 3” bundle of copper tubing, hang the indoor air handler on the wall, connect condensation tubing, set the outdoor unit, connect power and just like magic supply additional cooling and heating to any problem area.

Inverter vs. Non-Inverter Units

WARNING:  Mini-split air conditioners all look very similar but operate very differently. Traditional air conditioner units act like light switches – they are EITHER ON OR OFF.  They turn on, run for a while and turn off.  A mini-split with inverter technology acts like a DIMMER switch that automatically adjusts based on the required “load”.

Indoor portion of a ductless mini-split system

Inverter air conditioner units have several advantages.  First of all being comfort.  You will not have a big “swing” between feeling too cool and too hot.  Second is dehumidification.  By running longer at a lower level the inverter will pull more moisture out of the air resulting in better air quality and a “crisp” feel to the air.  Another advantage is energy efficiency.  Inverter air conditioners operate at a lower amperage and do not cause spikes in demand charge or light flicker when starting up.  Finally, the best feature of installing a mini-split air conditioner is CONTROL.  Whether it’s a bedroom, office or media room, you will be able to keep it cool and comfortable without having to cool the entire house.

Mini-split air conditioners are the fastest growing segment in the air conditioning industry.  Ease of install, efficiency, improved comfort and better dehumidification are just a few reasons never to throw in the towel on keeping comfortable.

Window with solar screen installed

One of the most frustrating problems is having comfort issues with a particular room in your home.  These are rooms that you can NEVER get quite cool enough no matter how hard you try.  The usual suspects are: Rooms over garages, bonus rooms, media rooms, master bedrooms that “stick out” from the house, and home offices.  In this article, I offer tips to help fix these problem rooms.

In order to fix the problem, you must first ask, “What exactly IS the problem”?

The easiest way to view any room is simply to look at it as a big box.  Heat enters the box and the air conditioner pulls the heat out.  The problem occurs when you combine several rooms (boxes) on ONE air conditioning system.  The airflow to each room will dictate how fast each room cools off.  The problem is that the sun, exposure, windows and internal heat loads (lights, people, computers, etc.) are DIFFERENT for each room and can CHANGE throughout the day. The “problem” rooms usually gain heat faster than the other rooms on the same air conditioning system.

Properly installed radiant barrier foil

There are two methods to TRY to fix this:  1) Keep the heat from entering in the first place or 2) Pull MORE heat out.

1) Keep the heat out – We want to STOP heat from entering so we don’t have to deal with it in the first place.  Start with the windows. If a window catches direct sun you need to shade the window.  Solar screens, window film, awnings or natural shade (trees) will all help – take your pick.  Then focus on the thermal envelope.  Walls should be well insulated and have some form of sheathing (usually ¾” foam board) on the ATTIC side of any walls to fully encapsulate the studs and the batts of insulation between them.  We call walls that face an attic “hot walls” for a reason.

Radiant barrier foil should be applied above and around any problem rooms. Ceilings should be sealed airtight and have plenty of insulation and ductwork should be checked for leaks or constrictions.

Open chaseway showing missing "blocking"

Finally, if the room is on the second floor, look for what is called an “open chaseway.”  This is the area between floors that usually has electrical, plumbing or ducts running through them.  Older homes often are missing “blocking” and allow hot or cold attic air to slide BETWEEN the floors and cook or chill the room from the bottom.  Open chaseways needs to be sealed up.

2) Pull MORE heat out – If you have done everything to keep the heat out and you still can’t stay comfortable, then the only other option is to pull more heat out. This usually requires the expertise of a good air conditioning contractor. You could need larger ducts, more ducts, additional return vents or a combination of these.

Unfortunately, on many “problem” rooms these measures have limited success. In fact, you can do EVERYTHING and STILL have comfort issues in some rooms.  What do you do?

Look for part 2 of this article: When all else fails – how to keep ANY room comfortable.