In a large pot, steam scrubbed clams in enough water to cover the bottom by two to three inches. When shells open, remove from heat. Set aside. Drain and reserve broth. Remove meat from clam shells. Cook bacon until crisp, drain, and set aside. Chop cooled clams coarsely. Using half the butter, saute onion, garlic, and celery in a skillet until tender, then place in a large pot. Add the clams and the reserved broth, potatoes, and carrots. Crumble bacon and add. Bring to a boil and simmer on medium-low heat, stirring occasionally, until all the vegetables are tender when poked.