Question about leaving heat on

[KrisZ]

Originally Posted By: Garak
I, for some inexplicable reason, turned my heater off in my Town Car with the remote starter one winter day. It was ridiculously cold. The engine was nice and warm when I got in, but the interior was decidedly not preheated, and breathing on a windshield when it's -40 and the interior hasn't been heated doesn't help visibility at all.

, I did this few times actually (now I make sure the fan is on), except I had to drop off my kids to daycare. Imagine three people jumping onto a stone cold interior, instant, thick fog on the windows. Even with the engine warmed up, once all the windows are heavily fogged up, it takes few minutes to clear just the windshield. And when it's real bloody cold, the fog becomes frost almost right away. So you're either scraping it off (that's real fun when it's on the inside) or waiting 10 minutes for the heat to do its thing.

 

[SwampSurvivor]

Originally Posted By: Garak
Originally Posted By: Miller88
It makes the car warm up slower. I turn the heat off and let it warm up. Then when I get in, I turn on the heat and instant warm air.

When it's -40 out, you won't be trying that. An extra half minute or whatever small amount of extra warmup time needed is irrelevant. The car is supposed to make me comfortable, not the other way around.

As KrisZ states, I prefer to leave it on defrost or defrost/floor if it's outside and I have to warm it up. I, for some inexplicable reason, turned my heater off in my Town Car with the remote starter one winter day. It was ridiculously cold. The engine was nice and warm when I got in, but the interior was decidedly not preheated, and breathing on a windshield when it's -40 and the interior hasn't been heated doesn't help visibility at all.


I do that for my comfort. I can either get in a luke warm car that has had all of the heat sucked out of the engine. Or I can get in a cold car, hit the heat and get full blast heat and be more comfortable.

 

[asand1]

Originally Posted By: boostedtsiawd
i heard the you can crack the radiator or damage something in the coolant system.


Quite the opposite actually. I forgot to turn the heat on one frozen morning. After the engine was warm I turned the heat on full blast and the windshield cracked.

If the heat was already on the window would have heated up gradually and not cracked.

 

[HerrStig]

Originally Posted By: asand1
Originally Posted By: boostedtsiawd
i heard the you can crack the radiator or damage something in the coolant system.


Quite the opposite actually. I forgot to turn the heat on one frozen morning. After the engine was warm I turned the heat on full blast and the windshield cracked.

If the heat was already on the window would have heated up gradually and not cracked.
"Something" ... maybe the flux capacitor?

 

[Garak]

Originally Posted By: Miller88
I do that for my comfort. I can either get in a luke warm car that has had all of the heat sucked out of the engine. Or I can get in a cold car, hit the heat and get full blast heat and be more comfortable.

Both my G37 and the F-150 will throw alarmingly high amounts of heat while warming up, particularly the F-150, with the small interior and HO heater core. I've had to take my parka off after getting into it when it was warming up outside in -40.

 

[SwampSurvivor]

My Cherokee will as well. The focus won't be throwing a lot of heat if I do this. It's a small aluminum engine.

It is a bit better with the new thermostat, but it's still a small aluminum engine.

 

[kschachn]

Originally Posted By: Miller88
My Cherokee will as well. The focus won't be throwing a lot of heat if I do this. It's a small aluminum engine.

It is a bit better with the new thermostat, but it's still a small aluminum engine.


Can you explain what it means that the block is aluminum?

 

[circuitsmith]

Originally Posted By: kschachn
Can you explain what it means that the block is aluminum?


Aluminum has a lower thermal resistance, so heat moves through it more readily and reaches the surface of the block and head quicker.
Before the thermostat opens a lot of cold air flows through the radiator into the engine compartment and cools the head/block directly from the surface.

 

[kschachn]

Originally Posted By: circuitsmith
Originally Posted By: kschachn
Can you explain what it means that the block is aluminum?

Aluminum has a lower thermal resistance, so heat moves through it more readily and reaches the surface of the block and head quicker.
Before the thermostat opens a lot of cold air flows through the radiator into the engine compartment and cools the head/block directly from the surface.


Well sure aluminum is a better conductor of heat, but the total heat available is dependent on the load and overall displacement of the engine. I guess I would have thought the delta-T through the heater core would have been more significant.

 

[SHOZ]

Originally Posted By: Garak
Never a problem. I do it all the time. I don't think anyone in Saskatchewan turns their car's heat off in the winter. They park it with it on full blast and let the thing warm up when it's -40.
If I did that to my Accent the engine would have a hard time getting above 120f at idle. Even driving down the road if I turn the fan above 1 it will take forever to hit 180f. Once it hits the 180f though it stays there or just above.

 

[Garak]

I accidentally let my F-150 warm up for 30 minutes one -40 day. When I went into the truck, the thermometer, which was not sitting in the air flow or in the sun or anything to skew it, showed 50 C, which is 122 F. All my winter gear came off in a major hurry, I tell you.

Another time, I had to drive it across town to a glass shop after a vandal smashed the passenger side window out. It was -20 C, -4 F, and I was wearing neither hat nor gloves, and was exceedingly comfortable. The thing throws ridiculous heat. The G37 isn't far behind, and is better for heat than any other vehicle I've had, aside from the F-150.