Is this a new thing with the temperature? 79F is way too hot for sleeping. The last time I flew LH, it was in F, and it was definitely not that warm. I was in shorts and a T-shirt though, and didn't use the blanket, sleeping uncovered. This weird heat thing is the reason I no longer will fly TK anywhere. Their cabins are kept oppressively warm. UA is mostly pretty good about cabin temp.

You would think that LH wouldn't want to waste fuel overheating the cabin in order to reduce the carbon footprint of their flights.

I think the FA made it up, or the OP misunderstood the FA. While long haul flights always seem to be too cold or to warm, I've never ever heard about a policy that sets an exact temperature, never mind one that is way too hot for humans to be comfortable indoors.

I agree - while I have heard stories of hot non-US cabins, all of my LH flights (mostly 747s upstairs) have been fine.

Correct non-EU/UK carriers are only covered by EU261/EC261 for flight departing from EU/UK. Arriving flights are not covered for non-EU/UK carriers.

For more see Best Practices for Filing EU 261 Claims Against United?

And let's return to discussing LH vs UA Premium Economy

Correct. That said, every time I’ve purchased a LH long haul PE ticket, about a month or so out they have offered a very reasonable upcharge for moving to J, something I’ve never experienced on UA.

What level of upcharge for LH? Does everyone have access to that?

I've had 300 for FRA-BOS this summer.

I've found TATL LH cabins more often too warm than not, often enough that it can't be random chance. 26C sounds about right for what I recall, since that's about my threshold for feeling uncomfortable in my normal travel wear of long pants and long sleeves. LX cabins are usually just right. UA cabins are sometimes slightly cool.

Not status chasing either way.

Thanks for the tip about IFE and the general point that UA is preferred. I left out one piece of the story which is that I am connecting in FRA for onward travel to Asia. That second leg will be on an LH 747 no matter which first leg I select. Seems like I should book the UA 777 SFO-FRA and then I will have the chance to experience both.

As always I appreciate the help and expertise of this community.

Bumping this thread up.

Booking a flight for early next year. I can either fly AMS - ORD/EWR/IAD - RDU on UA metal the whole was in PE/C+ or I can fly AMS - FRA - RDU on LH metal the whole way in Euro Y/PE. No upgrade availability with points and miles (no status) on the UA flights. I've flown UA in PE but never on LH. I'm inclined to go via LH as long as the products are relatively on par with each other because I'd rather land back at RDU vs. having to connect onwards but if there is a notable difference, I'll go with UA metal.

Looks like for 2026 the FRA - RDU flight is moving to a 787-9 if that matters

I would go with LH. I always avoid connecting in EWR and LH frequently has decently priced day of departure buy ups to business if you are interested in that.

There are plus/minuses to LH PremEcon. A couple of things to note. The meals are economy meals on china vs UA meals are derived from Business (for better or worst). And LH food may not always be to an American's taste.
LH's IFE is more international and less America focus --preferences will vary..
LH's carry on rules are much stricture.

This differences may or may not matter.

The more direct flight and connecting in europe is a plus in my mind.

Perfect opted to go this direction. Looks like I've actually got an offer at $680 for PE --> J which is more or less in line with what a 20k Miles + $400 upgrade offer would have cost for me to upgrade a United flight.

Just have decide on that but most likely going that direction which makes this a no-brainer (though won't get to experience the PE)