Correct position of heatercores.

I really don't know anything about watercooling at all. Automotive stuff I do know much more about. I've noticed that alot of people like using heatercores as the heat exchange device in their watercooling loop. I don't really know if it's well known but they're are two different flow patterns in heat exchange devices that I know of, side flow and top-bottom flow.

Top Bottom:
[+------------>]
[<--------------]
[-------------->] -

The water enters at the + and then flows to the bottom in the direction of the arrows and exits at the -. If you tip this heatercore on it's side the pump will actually have to push water up one row and then the water will fall down the other. I assume that would make it much less effective.

Side Flow:

+[----------->]
[<-----------]
[----------->]
-[<------------]

Same here, water enters at + and leaves at the -. The similarities in both of these designs is that gravity helps "pull" the water down.

Anyways, I was wondering if anyone was aware of this.

Well, at the speeds that the pumps run, gravity is not much of a factor, especially not with a car's waterpump.

Also of note, both my Taurus sedan, and Dodge Caravan have the inlet and outlet at the top of the heatercore, as they are mounted in the vehicle. I haven't looked in my Chevy Van or my Ford Ranger....


With the inlet/outlets oriented toward the center of the 'core or centered in each endtank as many are, sideways mounting would make for a bad air trap in each endtank and be quite difficult to bleed the air out of them completely.

I have my Dtek pro core mounted sideways and have not had any problems. Just give it a good shake to clear out any air that might be stuck.

The speeds that pumps run? I thought most water cooling pumps averaged around 25-30GPH (In application) and low pressure (anyone know the average pressure of a water cooling loop?). The average coolant system holds around 4 gallons (capacity), 7 psi but I don't know about volumetric flow. I guess the point I was trying to make was that if Ford built a heatercore to sit one way then there's probably a reason for it; and thus it works the best that way.

I do see that air could be issue though.

howlingyeti said:

The speeds that pumps run? I thought most water cooling pumps averaged around 25-30GPH (In application) and low pressure (anyone know the average pressure of a water cooling loop?). The average coolant system holds around 4 gallons (capacity), 7 psi but I don't know about volumetric flow. I guess the point I was trying to make was that if Ford built a heatercore to sit one way then there's probably a reason for it; and thus it works the best that way.

I do see that air could be issue though.

Click to expand...

pressure doesn't really matter. you want the highest Volume Flow Rate (Q) that you can get though. Q = Velocity * Flow area from here, you apply heat transfer equations. BTU = Q/(490 * temp drop in water) basically differences in orientation are negligible

howlingyeti said:

...The water enters at the + and then flows to the bottom in the direction of the arrows and exits at the -. If you tip this heatercore on it's side the pump will actually have to push water up one row and then the water will fall down the other. I assume that would make it much less effective. ...
Anyways, I was wondering if anyone was aware of this.

Click to expand...

I'm sorry, but that's not exactly how fluids work. If the inlet and outlet are at the same height then the pump is really only working against the resistance caused by the flow once the system is primed. The change in the height of the tubes is really insignificant, as a syphon effect will mostly prevent the effect you are describing. If you'd like me to go into more detail I can, but for the time being I will leave it at that. Now, the heater core's orientation may have an effect on trapped air, but that's a different problem altogether.

Ford's main concern is fitting everything into the vehicle in a way that uses the least ammount of materials ($) while giving acceptable performance that'll keep the customer purchasing again and again ($$$).
What I meant about pump speed is that with the powerfull pump used in a car, orientation is of little concern. Really it's driven by a 150+ HP engine with an impeller 3 times larger than a pond pump, and gravity isn't a problem.
As Skulemate pointed out, a closed system has no 'head hight' to consider, and can run in any orientation as long as the system is bled of air to make flow through the core efficient (for our smaller pumps).


And SoulEdge, your absolutely correct, but not everyone has the foresight to bleed the system before mounting it to the case.
Mine's hanging in the basement, and is seriously easy to shake the air out of it.

Well okay then.