Fill a large pot with lightly salted water and bring to a rolling boil over high heat. Once the water is boiling, stir in the pasta and return to the boil. Cook the pasta uncovered, stirring occasionally, until the pasta has cooked through, but is still firm to the bite, about 12 minutes. Drain well in a colander set in the sink. Transfer to a bowl and refrigerate until cool, at least 30 minutes.
Meanwhile, place the bacon in a large, deep frying pan and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain the bacon on a kitchen towel-lined plate, let cool and chop.
In a large salad bowl, stir together the ranch dressing, bacon, Parmesan cheese, carrot, celery and red onion until well combined. Lightly stir in the chilled pasta to coat with dressing and refrigerate 2 hours to blend flavours before serving.
Lettuce or cabbage can also be substituted for the pasta in this recipe for a lighter summer salad with crunch.