Quite a few gardeners grow yardlongs, including myself... I collect them. There have been several threads about them both here & on the Asian Vegetable forum; I've linked to one by another Zone 7 gardener below.

They will indeed produce well in heat, when common beans struggle. They bear heavily too. But I'd be the first to admit that the taste is not for everyone. Yardlongs are easily overcooked, and are best stir-fried or lightly parboiled. I most often use them in Asian soups, but they are also good as a side dish, seasoned with soy sauce, vinegar, and garlic powder.

The two best commercial sources I know are Baker Creek & Evergreen Y. H.; both carry a good selection. "Chinese Red Noodle" is one of the more popular, not only for its burgundy-red color, but its rich, somewhat nutty flavor.

Here is a link that might be useful: Yardlong beans

Cowpeas are related to yardlongs and also do well in the heat. Are cowpeas sold in seedracks in stores in the South?

thanks for reply zeedman you have been very helpful
ED