I have a 9 year old home and am starting a basement refinishing project. I will need both heat and AC in the basement. I currently heat and cool with a heat pump. Is there a way to determine the capacity of the existing system to see if it could handle the new space? What should I be looking for?

I have a rep from the company that installed the system when the house was built coming next week, but their reputation is not that great, so I want to have as much info in hand when I meet with him. Any suggestions would be appreciated! Thanks!

The only way to be sure is to do a manual j on your entire space plus the proposed project, and then compare that to your HP's heating and cooling capacity.

Is there a way to determine the capacity of the existing system to see if it could handle the new space? What should I be looking for?

The model and serial numbers along with the brand will usually tell you what size the equipment is.
The only sure way to tell if the system will handle the extra space is to do a manual J on the entire home. You can for a fee download and do your own manual J or have one done for you by a local specialist.

99 HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations 99

Next you should do a manual D for the size of the duct you will need.

Again you can do this yourself or pay someone to do it for you.

Here is a free bee

How to do a Manual D - Self Help Forums

These answers are from a professional aspect of the HVAC trade when no mistakes are acceptable. You can take it upon yourself to design or install whatever you want and any size you want but may times unless properly calculated to outcome will be a disaster.

FYI the average price for doing a manual J locally is going for about .10 (ten cents) per square foot but you need to do the entire home to see if the equipment that you have will do the job.

I would also look in to zoning the basement from the house so you can adjust the temp in the basement.