Coupling device for water heater and water heater

A water heater comprising a coupling device including:

• a water pipe connector having a mounting channel extending in an axial direction of the water pipe connector;
• a heat insulation pipe arranged within the mounting channel and at least partially spaced apart from an inner circumferential wall of the water pipe connector to form a balance chamber, the heat insulation pipe having a channel extending through the heat insulation pipe in the axial direction;
• and
• a heat insulation member arranged at the heat insulation pipe and at least partially located within the balance chamber, the heat insulation member including a heat insulation sheet at least partially extending into the channel;
• wherein the heat insulation pipe has a flow channel formed at the heat insulation pipe, and the balance chamber is in communication with the channel through the flow channel.