Hi Nellie,
I just retired from 40 years in the Building Supply Business, and want to wish you luck on the contractors. I just left Middleton Building Supply this past July, and the business is just crazy right now. I've never seen anything like it. Anyway, you might want to stop by the Dover or Middleton store and see if they know of any Contractors. Maybe stop by the Masonry supply place in Somersworth across from the Chevy dealership. Maybe they know of contractors for your Concrete work.
The heating shouldn't be a problem, but they are all very very busy, and it might take some time for them to get there. The bigger ones aren't cheap, but I know Martel Plumbing and Heating have always been professional, and will get you in line. Maybe Stogens, in Rochester? I haven't dealt with them, but they are one of the better known ones.
Be patient and understanding, but persistent. These are very trying times for the Building Business. I'm considering an addition for the Duplex I live in, and the Contractors were customers of ours, but they told me they couldn't do it until Late Spring of 2021.