End socket, inner container and double-container water heater

The utility model discloses an end socket, an inner container and a double-container water heater. The end socket comprises a middle barrel connecting part and an end socket part, a through hole communicated with the through pipe is formed in the seal head part, one end of the seal head part is sealed, and the other end of the seal head part is an open end; wherein the seal head part is connected with the middle barrel connecting part, and the cross section of the seal head part is smaller than that of the middle barrel connecting part. The middle barrel connecting part and the end socket part are arranged, the cross section of the end socket part is smaller than that of the middle barrel connecting part, the end socket part is provided with the through hole used for being communicated with the through pipe, and the cross section of the end socket part is small, so that an operation space for welding the through pipe and the through hole is reserved in the end socket part; the problem that in order to shorten