Quote:
Originally Posted by Stoker
At this point it's mostly theoretical. I'm thinking of trying to find a used 18 to 24K single zone unit to chop into. But ultimately if it would work on a single zone, why not a split unit?
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The main difference between mini-splits and standard-size split systems lies in the outdoor unit. All standard-sized systems have a liquid and gas line leaving the box. These two lines may or may not have the same pressures in them when the unit is running. There are no metering devices inside the outdoor unit if it is an air conditioner. If it is a heat pump, there is one metering device in the unit, which is matched to run the outdoor heat exchanger as an evaporator. Each indoor unit that is connected has its own metering device (and maybe shutoff valve) if the unit provides cooling. The gas and liquid lines leaving the outdoor can branch out to many individual indoor zones.
In contrast, most mini-split outdoor units contain all of the metering devices. In multi-split units, there is a metering device for every zone that has a connection. The liquid and gas lines in these systems are nearly always at the same pressure. In cooling mode, both lines are at much lower pressure than when the system is in heating mode. The indoor units typically do not have any metering devices in them. In essence, the indoor units always appear as unrestricted runs of straight plumbing to the outdoor unit. Each zone doesn't typically branch out once it leaves the outdoor unit.
This makes a big difference as to what you can connect to a certain system and what you cannot. It also makes a big difference when trying to troubleshoot the system when it isn't working correctly.