Technical Heater core hookup

Hi guys. Figured I’d ask for an opinion here on heater hose to core orientation. We are talking a SBC, and if I understand flow correctly the “pressure” side would be coming from the outlet on the intake manifold, and I’d put the water control valve on that hose. Then the “return” would be to the port on top of the water pump. So the question is this: would you connect the pressure hose to the upper or lower connection on the core?
Thanks
Pat

 

I would not worry about which heater core port it connects to.

 

Thank you, sir. I habitually over-think stuff.

 

I don't think it really matters which hose you use, but as you drive, the heat will build up in the core anyway unless you shut off the flow to both sides. I'm thinking about putting a manual valve on one side of mine to go along with the cable actuated valve on the other side, that way I could shut it off completely for summer and open it in winter, using the cable valve for heat control.

 

For maximum efficiency running the hoses so that the coolant fills the heater core from the bottom up is best. If you are just using the heater to take the chill off on cool days it probably wouldn't make much difference either way.

 

Also worth a mention, some heaters will be noisy if waterflow direction is reversed from what was originally intended.

 

Another consideration is a restriction on the inlet side. The factory inlet nipple has a 5/16 hole.
One of my adaptations, had no restriction. I blew out 2 heater cores while at WOT. The 3rd core I added the restriction. Was good after that. My thinking is the rad cap will build 15 psi, but the water pump at wot probably builds at least another 10. So your at 25 and "poof" there it goes.

 

My heater has "Inlet" and "Outlet" marked on each tube. It apparently does make a difference on some heaters.

https://static.speedwaymotors.com/pdf/359-640.pdf

SPark

 

I used to design and we manufactured heater coils, evap coils and condenser coils using the traditional 3/8" OD copper tube bent into "hairpins" with aluminum fins. Inlet and outlet, and orientation definitely matters on an evap and condenser coils, but on a heater coil not so much. Fluid flow was typically a "counter flow" design meaning for maximum heat transfer, you wanted the hottest fluid contacting the coolest air first. On a heater coil this may represent a slight loss in efficiency if not done "correctly". I can't say anything about where to tap into the SBC though.

 

heater cores get air across the core all at the same time, so I doubt it could matter much.

Some heater cores have a restriction in one fitting.

Some heaters have the water valve in the housing, with the core, and it might matter which hose connects to the valve, and which to the other side of the core.

But if it's just a normal heater setup, whichever hose routes to whichever fitting cleanest, is what I do.

 

Thanks for all the responses! Doesn’t seem to have any restrictions in either port and will use an external water valve. I read all of these, and I could definitely over analyze, but I think I will not. . I do like the idea of hooking them up backwards in the summertime for some a/c....hmm.....

 

I have a small aftermarket heater that I might put in my sedan, I purchased the manual valve and cable control. It came with a T that I assume is to reroute the coolant when the valve is closed.

 

You may want to think about air getting out of the system as it is filled and/or when circulating, sometimes air can get trapped in high points.