Mini split auto restart and connecting an additional thermostat

First Name:  Don

Last Initial:  M

Problem: Our split system is controlled by a remote. Every time the power goes out the system has to be manually turned on.This is a problem because our power goes out quite frequently and we have pets and are not always home to turn the unit back on.Can a thermostat be hard wired or is there some other solution?  Thanks

Solution:  Most mini split air conditioners have an “auto restart” function that turns the evaporator back on after a power failure.  When power returns the indoor evaporator’s electric circuit board will restart the system to the last setting before the power failure.  If you had the unit set at 77 degrees before the power failure it will return to 77 degrees at restart.  Make sure your equipment has the “auto restart” feature.  If it does you probably need the indoor evaporator circuit board replaced.

Mini split air conditioners are not built to have an external thermostat.  In order to attach a thermostat they would need to have an extra wire built into the circuit board.  They do not, therefore it is not possible..

Can you convert a single mini split air conditioner to a dual air conditioner?

From:  Chris M

Problem:  Hi. Is it possible to add indoor units to a compressor initially set up for only one indoor unit? Or put a different way: Could I install a compressor with the capacity for more indoor units than initially installed? Thanks.

Solution:  I get asked this question on a weekly basis so it is probably a good idea to address it to the public.  Mini split air conditioner are manufactured as either a singe (1 evaporator to 1 condenser) or multi-head systems (1-4 evaporators to one condenser).  When a multi-head system is manufactured it is built with a larger compressor that can handle multiple evaporators.  Trying to add a second evaporator to a single condenser would drastically effect the output size.  An even larger problem with trying to add an extra evaporator is that all the wiring and circuit boards are only installed for a single system.  There is no place to wire in a second evaporator.  And lastly, you would have to add two more copper line sets into the condenser which it is not set up for.  In short, there is no way to add more evaporators to an existing single mini split air conditioner.