In a large skillet, cook the bacon over medium heat until it is crisp. Remove bacon to paper towels. Drain the skillet, reserving 1/4 cup drippings. Saute celery and onion in drippings until tender., In a large bowl, combine the sugar, flour, salt, mustard, vinegar and water until smooth. Add to the skillet. Bring to a boil. Cook and stir for 1-2 minutes until thickened., In a large serving bowl, combine the potatoes, carrots and parsley. Drizzle with sauce and stir gently to coat. Season with additional salt if desired. Crumble bacon; sprinkle on salad. Serve warm. Refrigerate leftovers.,