Bring a large pot of water to a boil, and add dash of salt. Add the potatoes and boil until tender, but still firm, or about 30 minutes. Remove, drain cool, and cut into thin slices. Cook bacon in a large skillet on medium high heat until brown. Crumble the bacon and set aside. Reserve the drippings. Saute the onion in the bacon drippings until golden. Combine salt, sugar, celery seed, pepper and flour in a small bowl. Add mixture to the onions and cook until bubbly. Remove from the heat. Stir in the vinegar and water. Bring to a boil, stirring constantly, boiling for about 1 minute. Slowly add the potatoes and bacon, stirring gently until the potatoes are cooked through.