Fill the crock pot with full strength anti-freeze coolant until the pipes are fully submerged. Put the crock pot on low and put the lid on. Let the pipe cook on low overnight. The next day remove pipes and wash with clean water. If there are afew stubborn spots do it again after brushing them with a tooth brush. Carbon off is also a great product, but I prefer the anti-freeze method becuase it helps to remove the carbon deposits inside the pipe as well.

That crock pot really shouldn't be used for cooking after that. The anti-freeze is also reusable for cleaning pipes again and again. Just remember the stuff is toxic, and the fumes are as well.