Question from HEGS
We have purchased an old home without any ducts, that is heated with radiators. We are interested in installing central air conditioning and I just learned about ductless mini-split air conditioning, which is a less expensive way to install air conditioning in homes without existing ductwork. I don’t know much about these systems and I was wondering if you or your readers knew about any environmental or health concerns associated with them, and if anyone has experience with their efficiency?
Thanks.
Debra’s Answer
I think this is a relatively new product because I only just heard of it for the first time within the last month and a unit is on display in a prominent location at my local Home Depot.
Here is a simple explanation with photo US Department of Energy: Ductless Mini-Split Air Conditioners
We need a new air conditioner in the near future and I’m looking at this as a replacement for ours.
The one I saw at Home Depot is made entirely of plastic, which I wasn’t fond of, however, I think the plastic needs to be researched to see what type it is and if it would pollute the air in any way.
Could you find out what type of plastic it’s made from? Then we could discuss it further.
Ductless mini-splits have been used in Europe and the Middle East for years. They only work well in fairly open homes with good building enclosures – a home that isn’t drafty. The only way to really know if your home is drafty is by having a Blower Door test performed on your home. There is no way to actually commission the system so it is important that a Blower Door test is performed to determine if your house is leaky and needs air sealing. Then a heat load calculation should be done so that you are sold a properly sized system for the heating and cooling load that your house is subjected to. This calculation is often called a Manual J load calculation. Mini-split blowers modulate themselves so their efficiency is difficult to measure because the blower speed will change depending on what the unit senses it needs to blow. I don’t know the toxicity of the cabinets or what they are made of. They definitely are not made by companies concerned with keeping toxins or off-gassing out of our homes.
Ductless mini-split air conditioners have been very popular in countries like Japan (e.g. Mitshubishi’s Mr. Slim) and are gaining acceptance in the USA as the price drops with demand. Because the “guts” of the system are outside, you escape exposure to many items that ordinarily might be challenging and they are wonderfully quiet. The trick is to ensure that you use short ducts that can be cleaned much more easily, rather than permitting an installer to use longer ducts that may harbour dust and mould and require professional cleaning with problematic substances that may contaminate your home). Careful landscaping and tandem ventlatk2ion can help reduce your need for multiple ducts.