kingofdodge7131

And your talkin to a man that operates 23 over the road trucks. We never had a problem when every truck left at the same time every day, but when they started leaving when the outlet circits timed on and heaters started going bad all the time the dealer sent a rep out and guess what we found out? the trucks that kept going out were trucks that left during current on times and the rep confirmed that starting the truck with the element plugged in has the ability to crack the element. Those people who dont pay for the repairs seldom know what there talking about aka you. if you have nothing constructive to say then shut the up. I added something constructive. by people who are know what they are talking about. Amen

HMX-1

My Dad used to leave his trucks plugged in until he started them (6.2L engines) and I used to holler at him for doing it. Now as a teenager at that time most will agree its unwise to holler at your folks. After the second time of him driving off in the truck while it was still plugged in and me being the one that had to fix it AND hear him holler about doing it, I was tired of being the one that got the butt chewing I didn't merit.

So I'd just repeat very loudly .... UNPLUG IT ..... UNPLUG IT ..... UNPLUG IT ..... until he finally would and mutter some unmentionables under his breath about the extension cord.


-K

CamperAndy

The temperature Coefficient of copper is 0.00393 ohm per degree C. So the effect for a 750 watt heater (which runs a nominal 19 to 20 ohms) with a 100 degree C change in temp is .39 Ohm or about .1 amp of initial change in circuit draw. That change as you can see has almost no effect to the element output or function and then when you add the fact that as soon as you turn it on it heats up to operating temperature then ambient has no impact on the circuit.

As for the impact on cold water hitting a hot element, not going to happen unless there is no thermostat in the truck and even then it would not be a massive shock. Now if the element were turned on without being in water and allowed to heat up completely then you pour some cold water on it you could cause some thermal shock issues but then that is not how the heater is used is it?

Not an engineer but I did stay at a Holiday Inn Last night. Got to love these threads. Simply question leads to complex and irrelevant answers and charges of post count inflation. To answer the OP, you can leave it plugged in 24/7 but it is a waste to do it that way. Put it on a timer and have it come on 3 or 4 hours before your normal start time.

ghenges

My initial reaction to kingofdodge7131's information to unplug the block heater a few minutes before starting was that it was kind of "out there".

However, kingofdodge7131 IS a man that has real life experience operating 23 over the road trucks as opposed to those with the academic theoretical laboratory approach or those just shooting from the hip.

The more I thought about kingofdodge7131's statement, the more it made sense.
The element is at its maximum temperature and immediately surrounded by the hottest water in the block. Then the element is slammed by minus 40 degree water from the radiator. A potential 200 degree difference is a possibility.

Then I thought as to why we never experience element failures.
We have always unplugged before starting (without knowledge of the benefits).
We have always used distilled water in our engines. Hard water encrusts the elements with lime scale which leads to early failure. If you can hear your element "hissing", it's probably from hard water, with soft water you can't hear the element..
An lime encrusted element is an insulated element which would make it more vulnernable to the failure that kingofdodge7131 describes.

I'll go with the man with REAL WORLD EXPERIENCE every time and I thank kingofdodge7131 for the education.

It is amazing this man's good information got trashed here. If you can PROVE he is WRONG then respectfully debate the issue, no one has yet PROVED his experience based knowledge to be wrong..
It is also amazing the aversion to learning that occurs on the internet.
I searched for a year on the internet to find a method to cook at home Prime Rib as excellent as at a local restaurant.
I found the information and can now crank out absolutely perfect Prime Rib.
The guy that posted the information I used to perfect my method was severely trashed and derided, the man is still being criticized even now.

The point is, no matter how perfect your information or how educationally valuable there will be those that will trash it. Just call it an aversion to learning. The internet proves there is such a thing as too much democracy which leads to information pollution.
The downside is that people with superb intelligent information are less inclined to post their valuable information, why bother posting if you're disparaged by the very people you're trying to educate.



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05 Ram 3500 SRW

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lmao hairy
thanks guys for the other posts

DodgemnLeavem

lmao hairy
thanks guys for the other posts[/QUOTE]

lol ahh ya gotta love this place.