So this is the year you finish that room on your house. You’ve met with the contractor and approved the plans. Now it’s time to decide on an air conditioning system.
The contractor suggested a ductless mini-split, which doesn’t require any ducts running through the walls. But how to choose a ductless mini-split for that Florida room, sunporch, or addition you’re building? While the contractor can recommend something, you’d like to know a little more about this expensive air conditioner you’re purchasing.
Here are three questions to ask: How many zones? How many BTUs? How will it be installed?
The zone question is paramount, and probably the simplest one to answer. Two rooms, two zones. Three rooms, three zones. Your contractor should perform a calculation called a Manual J to analyze how much cooling power you will need.
The BTU equation for a single zone is fairly straightforward. For a 100 to 150-square-foot room with two occupants, out of direct sunlight but not too deep in the shade, with no cooking appliances (barbecue grill?), it’s recommended you buy a 5,000-BTU unit.
A system that has multiple zones is a bit more complicated. Each zone has an independent indoor unit (air handler), but you can connect up to four zones with one outdoor unit (condenser). The total BTUs of the indoor units can exceed the capacity of the outdoor unit by as much as 30% as long as all units aren’t operating at maximum capacity at the same time.
The installation question depends on your personal preference. You can get a unit that mounts on the ceiling, or is suspended or hidden (recessed) in the ceiling, or you can opt for a wall-mounted air handler. Some people have a real aversion to the sight of the air handler, but they come in sleek designs and are not particularly obtrusive.
If you need to cool and heat the room, you might consider a ductless heat pump. For a comparison of AC/heat pump ductless mini-splits, see our buying guide here: http://www.acdoctor.com/Ductless-Splits-p-1-c-183.html.
And yes, you definitely need an HVAC contractor to install these babies— no matter what you might have been told.
Enjoy that new room! Stay cool!