In heavy Dutch oven, cook bacon on medium heat until crisp.
Remove onto paper towel and poor off most of the drippings.
Return pot to heat, add butter to melt and whisk in flour
Cook on med-low heat 2 min to make rue
Whisk in half n half and milk, turn heat back up to medium and stir while milk thickens slightly. About 20 min.
In separate large saucepan, add celery and whole onion to enough
water to barely cover, simmer for 30 min, with lid
Peel and cube potatoes into 1/2-3/4" cubes (Not too big)
Add to simmered celery and onion, cook until just tender
Add thickened milk, bacon and clams
Salt and pepper to taste
Remove celery chunks and onion.
I blend these and add all or part back into chowder.
Serve with crusty country bread