The main caveat with multi-splits (multiple ductless heads on one outdoor unit) is that they really need to be well thought out to have them work well and be efficient. Even the smallest heads are usually too big for the loads in bedrooms, so they turn on and off a lot (which hurts efficiency) and sometimes they overcool (when cooling) or overheat (when heating) the space. That's far less of an issue with single mini-splits, because they can modulate their output to match the load, whereas multi-splits can't really. If they're done right they can work, but with a contractor who doesn't really think too much about load calculations (most don't), sometimes the performance is pretty poor.
Though if they're just being used sporadically (rather than using them as the primary heating system as well) that's probably less of an issue.
|