"Engine Preheat" vs. "Engine Heater"

[Pete Masterson]

As I watch the snow accumulate outside the window, I realize that I
have two switches that would seem to refer to the same function:

On the panel on the left above the driver's head, I have an "engine
preheat" switch with a green light that comes on when the switch is
activated. I also have a red, home-style switch on a panel just below
the galley sink, next to the Konstant Hot switch that reads "engine
heater" and the switch glows red when it's turned on.

Do these switches turn on the same thing? The owner's manual mentions
(without much detail, of course) that the AquaHot system will heat
the engine for cold starting.

Therefore, do I turn on both switches or will only one do the job?
Does anyone have a feel for how much time it takes to warm the engine
in freezing temperatures... last spring when we spent a week in the
Denver area with temperature lows frequently dropping into the
mid-20s, I turned on the "engine heater" switch about 10-12 hours
before departure. After many tries and much stumbling the Series 60
finally but reluctantly came to life.

I'm thinking I'll turn on the switch(es) about 24 hours before my
planned departure this time... or should I turn it on sooner?

TIA

Pete Masterson
aeonix1@...
1995 Wanderlodge WBDA 42
On the road at Idaho Springs, CO