heater query 4.6 gems

good day;
please if someone may assist me,i want 2 inquire about the two pipes on the bulk head going to the heater matrix,upon touch and at engine normal temperature the top pipe(inlet as i supose) is warm to touch,and the bottom pipe (outlet?) is burning hot.when i switch my heater on i get warm air not burning hot and it seems to get hotter when i accelerate on steady base at 1500 rpms.how can the inlet pipe be warm and the outlet pipe be hot it must be the oppposite or same both very hot or what?or i am confused with the in or out pipes?car is not overheating nor coolant getting lost.
when i tested the heater the outside temp was 35 maybe that is the reason y i felt the air warm?
water pump seems to operate normaly not weak,i checked it by removing the top radiator bleeding pipe and there is steady flow from radiator.
thank you

any thoughts?

a big heat differential between the two pipes could indicate a blocked matrix, take off both pipes and flush with garden hose, flush both ways and at full normal tap pressure.

gavbriggs said:

a big heat differential between the two pipes could indicate a blocked matrix, take off both pipes and flush with garden hose, flush both ways and at full normal tap pressure.

Click to expand...

Thank you,i will do that,i'm affraid 2 have a surprise in the matrix from the previous owner and end up having a leaking o ring or discover that the previous owner blocked it due 2 a leak,but i'm affraid it has 2 be done.