Connect each inlet to the supply authorized by the manual. Having only one supply line in the home does not mean a dual-inlet washer will work with the other port capped or connected through any kind of branch line.
Identify inlets and conditions
A machine may be designed for cold water, for cold and hot inlets, or for a special documented supply. The connection labels and the manual should confirm what each port receives and the temperature and pressure limits.
In certain appliances, both inlets take part in cycles that the user may consider cold or lukewarm. The Whirlpool dual-inlet documentation requires both connections in its context; that condition does not apply to every appliance with two ports.
What can happen if you switch them
The control may receive water different from what it expects, alter mixes, or fail to reach the expected temperature. This affects both the load and components and stages. If one inlet does not work after connecting, the cold or hot water troubleshooting guide can help separate installation issues from a fault.
Preheated water and energy balance
The heat of washing can come from the appliance or from an external supply. Connecting water from a water heater or solar system should only be done when approved for those conditions. It does not guarantee savings: available temperature, pipe losses, and energy used outside the machine all matter.
If only one supply line exists, check for an approved solution before modifying pipes or joining ports. The hose connection must preserve seals, compatibility, and access. When calculating consumption, also count external energy when it is part of the wash.
Resolve supply compatibility before choosing adapters; the program setting does not correct an incorrect water connection.