Hi! Welcome to BYC!
I will give you my opionoin based on our experience. Some of it may or may not apply. I live in MS and we have semi-cold winters but it does get below freezing often. For our first nipple water system we elevated a 5 gallon bucket (for gravity) and ran pvc pipe through the coop, inside the run and outside of the run. Nipple drinkers were in all three places. We had problems with the pipes outside of the coop freezing and the nipples would be pushed out. The ones on the inside were always fine. Because of this problem, I wraped the pipes with that black foam insulation made for pipes. Well, the chickens decided that it was fun to peck the foam and pull it apart. I ended up wrapping the insulation with black duck tape and that solved the problem with the pecking. All of that ended up being such an ordeal that we decided to just do hanging 5 gallon buckets with the nipple drinkers pushed into the bottom. That was much simpler and works great inside of the coop. We also hang some of those outdoors during the summer.
I don't know much about heat tape, but some sort of insulation would probably not hurt. I would never want to go back to traditional waterers so if you can figure this out I think it will be well worth it in the long run. I would also suggest using the "push-in" style nipples vs. the screw-in. They work better for us as far as leaking is concerned.
You may also find more information about this by doing a search here on BYC for something like "nipple waterers freezing" or similar. Good luck and I hope you get it all figured out.
