We’ve decided to rent out our mother-in-law suite, and would like to put it on a separate HVAC system. How does this work?
If the unit you currently have is big enough you could possibly add on. If not, you would need to either replace with a larger unit if possible (depends on other factors also). Or you could add a whole new second unit. Depending on the space, I may suggest a ductless wall unit also. Cost really can vary greatly based on which direction you chose to go, size of space to cool, efficiency rating, down to the state you live in and costs. We have done units for as little as $2,800 and up to $15,000.
Your best bet is to get a few quotes- most of the time they are free and you will get a better ball park from there! 99% of suppliers will need to come see the location before the quote can be made.
Utilizing a zoned system is the most cost-effective way to condition different parts of your home. Typically it costs about $1,000 per zone. Everything depends on the size of your home. Most people will have a zone for upstairs, and one for downstairs. The zoned systems only work for zones sharing the same ductwork, though. Is the in-law suite detached from the house? If so, a mini split system will be the best way to go.