Generally, a radiant heating system is a closed, secure vessel, which means it shouldn’t leak. If it does, there’s usually a good reason for it—like the system has corroded, or a fitting has failed, or a pipe has been damaged, or just terrible luck has befallen the system. So leaking isn’t good. At best, it means the system has been slightly compromised and is probably slightly less efficient than it was designed to be. At worst, it could cause significant water damage to the structure the system is installed in. Because regular maintenance can usually catch any issues that might lead to a leak, leaks can generally be avoided.