I doubt you could find any yancha in Chengdu
but I could be wrong.
I don't like any any tea house in Beijing. Most of them are very expensive, although there are some nice, fancy ones. There is one called 圣淘沙 (Sheng Tao Sha) that's not bad and medium expensive. Oh actually I just recall this one is from Chengdu, so I am probably wrong saying there is no yancha in Chengdu
But this one is quite different from typical tea houses in Chengdu. Most tea houses in Chengdu are cozy, nice people's
tea houses, while those in Beijing are mostly rich businessmen's
tea houses. But you can always go to Maliandao or other tea malls to have free tea.
If you are lucky, you can get better tea there for free than $20 per pot tea from a fancy tea house.
Another reputable one in Beijing is 五福茶艺馆 (Wu Fu Cha Yi Guan). It used to focus on southern Fujian and Taiwan tea. But nowadays most tea houses sell whatever expensive
There is another one, Lao She Cha Guan （老舍茶馆）. It's mainly for watching traditional Beijing shows than tea appreciation. But it could be nice if you like the show.