Heater core tubing size

[dodj]

Why are they different? 5/8" and 1/2".
What goes in must come out..so...????.

[Mrbill426]

Just a guess but it might be to slow the flow to heat up the core 

[dodj]

Hmmm...   Maybe.
I read somewhere that they are different so you don't hook it up wrong as well. But I find it hard to believe it really matters which way the coolant flows in the core? Maybe it does? 

[Mrbill426]

No I don't think it matters. Unless someone in the "know" pipes in with the textbook answer I am sticking with my guess.

Hmmm...   Maybe.
I read somewhere that they are different so you don't hook it up wrong as well. But I find it hard to believe it really matters which way the coolant flows in the core? Maybe it does?