Why does the upper radiator hose stay hot while the lower hose along with radiator is cold with no heat in dash after replacement of bad water pump and thermostat?

YOU PROBABLY HAVE A BAD OR CLOGGED HEATER CORE IN THE VEHICLE. DEPOSITS AND SEDIMENTS CAN FIND THERE WAY INTO THE HEATER CORE (NORMALLY LOCATED INSIDE THE DASH ASSEMBLY). NORMALLY A FLUSH OF THE CORE WILL HELP YOU OUT, IF NOT, A NEW CORE WILL BE NEEDED.

The core was really clogged, but under pressure it blew out, flushed the engine. Lower hose to the heater core coming from the engine is very hot, while lower radiator hose is almost even cold, what do you think?