We installed a steam boiler in a hospital to be used for sterilization. The job was completed mid April. The customer paid 65% up front per the contract and has failed to pay the balance. The installation passed both the city of Houston and the state of Texas inspections.
Assuming the hospital is not a government entity, then:
If you are the original contractor, then file a lien and file suit to foreclose it.
Assuming you are unable to foreclose on your lien, you may be able to sue the customer for breach of contract if they have not paid you the agreed upon price. However, before getting that far, sometimes a well worded demand letter from an attorney's office, demanding payment is enough to get paid. Either way you will probably need to contact an attorney to discuss next steps.