wow, thats exactly what i was wondering about.  the numbers seem to make
sense on a ballpark basis, seems to point towards use of the heater as a
good thing, regardless the electrical drain ...

----- Original Message -----
From: "Steve Cotsford" <Cotsford@aol.com>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, May 16, 2001 4:16 AM
Subject: Re: aiding cooling system by turning on heater blower

> When you turn on the heater blower,  you will probably draw about 10 amps
at
> max position.   This means you will be consuming about 12 x 10 = 120 watts
of
> electrical power.
> 1 HP is 746 watts, depending on the unit system, so your fan is consuming
> about 1/6 of a HP which even for the Vanagons engine is not that much.
> The heater core is probably capable of rejecting about 25% of the engines
> heat so by using the heater fan you can easily make the difference of
> overheating an engine or not overheating it.    A good chunk of the energy
> from gasoline is turned into heat with a combustion engine.
> Very roughly speaking, a 100 HP engine can produce more than 60 HP in heat
> loss which your radiator system has to reject.    At that rate your heater
> core can reject 15 HP.
> These are really really round numbers so dont be tempted to take me to
task
> over efficiencies etc.    I am attempting to show how effective using the
> heater fan can be to cool an engine.
> Not sure about the Vanagon set-up but most vehicles have the heater
plumbed
> into the water system upstream of the thermostat so if the thermostat is
> defective and wont open, using the heater at full blast can allow you to
> gently drive somewhere for help.
> Hope this is clear,
> Steve Cotsford
>