I would like to see model number for AmStd quote. I will assume it includes the new addition area as well as existing area eliminating need for the mini split. Please confirm. This pricing includes zoning controls? Without more details, yes, I think the pricing is over the top too.

IMO

Thanks so much for your response. I've asked my contractor for the exact model number. Yes. the second option will include the addition, so no mini-split. I believe we will have two zones.

If you have read any of my comments you are aware I am a proponent of mini split systems for several reasons. Am in my second home with them, talked a friend into doing the guest house with one in 2009. No problems if installed correctly. (This one was installed by a company who 1. Had never installed one.2. Was a crooked company. After Fusitsu sent out a company who corrected the wrong installation there has not been a problem. I use it a lot. More for ac than heat. Central Florida. For myself- I would have the mini split for the addition- if your main breaks down you will still have a warm/cool place and not be uncomfortable or panic until repaired. Depending on where you live this might be important. 100 degrees here today. If I only had one source of ac and it broke on a holiday I would be a very miserable camper. The cost of a unit for 500 ft2 is too high, though. My neighbor is going to build a new home shortly and wants to use mini split after seeing/being in my home often.

No problems if installed correctly.

This is really a misnomer because it applies to ANY equipment. That is the problem that can't be ignored.

I am an opponent of the mini split for the simple reason they are more or less single room air conditioners. In other words you are going to need space on a wall in every room to mount the cooling/ heating head. (more equipment)

The mini splits could all go down at the same time... this depends on the design of the system. They make multi head capable condensers... meaning multiple cooling heating heads connect to one condenser.

If the condenser goes down, there is no cooling in any head. If you put in multiple heads and multiple condensers for those heads then that is even more equipment to maintain.

The only way yours are still functioning is that they have been maintained. Maintenance is not free and if you don't know how to do it, you are more likely to damage the system.

Look at the facts you'll see I am right.

If you save anything up front in a mini split you WILL pay for it at some point in the future. More equipment = more cost. No way around that and repairs will be much more complex. Watch the video below for in depth look at how much fun you might have...

The addition should be a separate zone. The mini split would work well if you don't mind having a heating and cooling heat mounted on the wall. If you search the forum you will find posters complaining mini split installations tend to be pricey. I think your quote falls into the range I have seen reported.

It hard to comment if the American Standard quote is reasonable without knowing the equipment and how much labor is needed to install new duct work. This would be a two zone system. I am not sure how this would work with a gas pack. Many contractors don't do a good job when it comes to zoning. Your contractor likely knows little about HVAC and is repeating whatever the subcontractor is telling him. You need to ask a lot of questions.