Loop legnth is a HUGE factor on your energy use/ performance and comfort. My advice to you is to hire someone from the IGSHPA Accredited Installer list in yor area to design it for you based on your needs. THis may be a small cost but a huge advantage. Then hire them to spec the driller what do drill. Also look at installing a no pressure system , it is a great option . ! Then have them log all data and do a test of performance before and after the job is done. That will be a great end result. Remember PA is a HEATING climate, bores should be treated as such. Its a good first question to weed out a non performing design .