AquaHot engine preheat function

[hmitchmd]

There is an engine preheat function on my panel where my AH controls are, and I was wondering under what conditions I would use this. I assume it’s only for cold weather, but how cold, and how long would I leave it turned on? Thank you in advance.

[dizcom]

There doesn't seem to be hard numbers for this, although it may be in your manual. There have been other threads on here that you can take a look at where this has been discussed and several articles out on the interwebs. Some people put them on when it's colder than 40, some when it's colder than that. An hour seems to be about the time that people turn them on before starting.

[n2zon]

I have found that 20-30 minutes is plenty when it's 20F outside if you turn the diesel burner on. You can turn the key on and look at the temperature gauge. When it's close to 100F (on the low side), you're ready to start the engine.

[alank]

Freightliner service rep told me with these newer Cummins engines, if it’s 40* or more, crank it up. Less than 40*, I would heat it for 30 min. With the diesel AquaHot.

[emdoc]

From the 450D manual:

Engine Preheat- In order to use the Engine Preheat
element on the Aqua-Hot system, both the diesel burner AND the engine preheat switch must be turned ON. Allow the engine preheat element to function for one hour before starting the vehicle's engine.

http://www.aquahot.com/files/owners_...ide450DWeb.pdf

Diesel Engine preheating: https://www.rvtechlibrary.com/engine/preheat.php

Outside temp varies as to when to use. If it's in the 40's or less, I tend to turn it on an hour before we leave. Is that necessary? No, your engine will start without it. I see no harm in using it with a lot of potential benefit starting a warm diesel. We are running the Aquahot anyway for heat and hot water.

[hmitchmd]

Thanks to everyone for your replies. Good information. I’m camping where it’s pretty cold.