Dog Pooping in the House?

I have a fixed male Fox Hound who is 3 years old. He doesn't poop or pee in the house in the living room where he is kept all day when we are gone. We have him outside for about 2 or 3 hours after we get home, then let him in. Then he poops in the house.

I got him from a young man when the dog was 10 months old. The dog had separation anxiety after he he moved in with us, so the vet put him on meds.
We had caught him urinating several times over the last couple years on the carpet. I treated the spots and thought he had stopped. It turns out we were very wrong. We just recently had to tear up the whole room's carpet and padding because the odor was sickening. The padding was completely soaked underneath while the surface was dry.

I am not positive when he was urinating because we never caught him. We just happened to find a spot because he lifts his leg and the sheets I took out of the bottom drawer smelled horribly of urine. Then we found a jacket we had hanging on chairs was peed on and the clothes hamper was peed on. That is how we found out.

He hasn't urinated on any carpet since we pulled that carpet up. But he continues to wait until he comes back into the house to poop.
Can anyone give me advice? Otherwise I have to get rid of him or put him in an outside kennel. He is so sweet and loving, but costing us a ton of money.