If it's not below freezing, we usually run the block heater for a couple hours in the morning as we pack up for travel. If it's colder than that (we try to avoid those nights) we'll turn in on the night before and let it run overnight. Using the block heater this way the engine always starts just as if it were a warm summer day
If it's going to be freezing or below for the night, we turn the block heater on at bedtime if we are leaving in the AM. Right at freezing does not seem to be near the problem as when it gets in the low 20's or below for an extended period of time.
It's just easier on everything to spin a warmer engine. Frankly, we try to avoid traveling or even being in those kinds of temperatures.
Below 30* is an average. How long depends on the type of heater. Obviously an electric block heater will take much longer than an AquaHot. I'd leave the electric block heater on overnight if leaving in the early AM with sub freezing temps. Aquahot with an already warm boiler will only take a few minutes.
1976 Newell Classic (Sold)
Home Base: Riverside, CA
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