In a message dated 6/10/05 2:29:38 AM, rrecardo@WEBTV.NET writes:

<< Pipe dream. >>

Hardly so, Recardo.  I saw the temp gauge go up a little, not much but
obviously, whenever I toggled the rear heater valve from off to on.  It worked in
reverse also.  I repeated it enough times to make sure the action was producing
the reaction.

Think about it.  A certain mass of coolant with a certain heat content is
shunted through a 6X9 heater core sealed in a box in a van's cabin and it gives
up some heat.  Now, take that same mass of coolant and instead direct it
through an 18 X 24 radiator core hung in free air while also radiating its heat
along two 10 foot lengths of 1 1/4 pipes.  Which slug of coolant would you expect
to come back home cooler?  I already know the answer to that one.

Now, if you want to connect the rear heater core in series with the radiator
and run ALL the coolant through both of them, you then have a point.

George