Yes I was talking in extreme cases. Just depends on a few variables (fuel level, run time and how hard the truck is worked). I know on heavy trucks with Detroits will heat up the entire fuel tank in a few hours. Like I said, thats much more extreme than most people on here do.
Seems to me that the more times that fuel is moved it gets more air in it. Is anyone running fuel coolers? With the dead head it's always adding fresh cool fuel into the head, yes the fuel in the head is hot but not the fuel coming in. With an rr, all the fuel in the tank will be hot...
The glass gets full? I don't see how it will fill any faster by having the plumbing make a loop before the sink and dumping back into the well. I'm sure it's a lot easier to bleed the air out of the heads with an rr. I just don't see how it gets more fuel to the injectors.
Could a guy use a rheostat type switch instead of a toggle? That way you could apply it with a twist of the knob instead of all at once like a toggle. I'm just thinking out loud here.