3/4 and 5/8 heater hoses why

[tyler]

Replacing all heater hoses...

Can someone explain why one stretch is 3/4, and most is 5/8?

And which one is flowing away from water pump?

I'm replacing the "Y" connectors to house water heater also, the part said 3/4 hose, but fits the 5/8 better and trying to figure out if the size
matters as long as no leaks.
--
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC

 

[Matt Colie]

> Replacing all heater hoses...
>
> Can someone explain why one stretch is 3/4, and most is 5/8?
>
> And which one is flowing away from water pump?
>
> I'm replacing the "Y" connectors to house water heater also, the part said 3/4 hose, but fits the 5/8 better and trying to figure out if the size
> matters as long as no leaks.

Tyler,

That is actually a very good question. And as it happens, I know the answer....
It was done that way in many vehicles by the OE so the hoses could not easily be reversed at assembly.
Not because the flow direction in the heater core matters. (Well, it does, but only a little in some cases.) But because those system with a control
valve, the direction of the pressure (which isn't much) can matter a lot for the valve to truly stop the flow.

Matt

--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[scott nutter1]

Matt..Thanks!!!
I've always wondered why also. But too afraid to ask..I just thought the outlet hose would be larger because of expansion of the liquid going to the
cooler..but I'm also one of those morons while in high school who would squeeze a smaller hose on a larger nipple or Vice versa with a larger hose on
a smaller nipple and hose clamp the poop out it......
You guys are awesome!!!!
Scott.
--
Scott Nutter
1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, tankless water heater, everything Lenzi. Alex Ferrera
installed MSD Atomic EFI
Houston, Texas