I have a Central Boiler since 2004. I heat my 1900 sq ft home, hot water, spa, 900 sq ft attached garage as well as my 5000 sq ft pole building with about 12 cords a season. If I did not heat the pole building I am sure I could get by for about 8 1/2 cord. If your son is burning 30 cord there is something amiss. Any chance he is talking face cord? That would make sense.
Seasoned wood is far better than trying to burn green wood. Maybe that is why he appears to be burning so much. Seasoned wood produces FAR less smoke and you are not wasting energy burning the moisture out of the wood. Plus we need to keep as low a profile as possible as far as smoke is concerned, the less smoke the better. The greenies are hard at work trying to shut us down.