cabin heat

[Jayemtee]

It was my understanding that coolant flow is only restricted by the thermostat. Once it starts to flow, the heater core and hoses are part of that flow path without regard to HVAC settings.

[firsthonda]

Originally Posted by mrkcohen

It works because by leaving the heat/fan off you remove the heater core from the coolant loop. Less surface area for potential heat loss means faster engine warm up time.

It's similar to leaving you oven door partially open when pre-heating. Sure the oven will eventually reach 350, but with more paths for potential heat loss it will take longer.

That's the way I understand it. Not turning on the heat right away, for me, in every vehicle I've ever driven, has always resulted in faster warmup.

[Cobb]

Same here. Just don't confuse the fact the t stat only diverts the flow of coolant to the radiator once it hits 180? degrees where as the cold engine light goes off at 140 degrees. I find when I abuse ev mode, coast, etc I feel the heat fizze out and when under a load it feels deep n warm.


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[Jayemtee]

I'm not trying to bust anyone chops. Whatever works, go for it. I was just trying to figure out if it was something you knew mechanically that I didn't know, or if it was something that you've always heard.

I think that if you draw a fluid schematic of coolant flow, the heater controls are not involved.

OTOH, if you wait until the car is fully warmed up before you hit the heater switch, the WOW factor of instant gratification is much higher than a gradual warming.

[Zwolfe]

Originally Posted by Jayemtee

It was my understanding that coolant flow is only restricted by the thermostat. Once it starts to flow, the heater core and hoses are part of that flow path without regard to HVAC settings.

Right.

There IS something to the heat-siphoning effect of having the heat turned on though. For instance, say the belt the water pump is connected to busts ... your only savior now is turning heat on with the fan on full blast, aside from air entering the front grille.

Eventually, though, the engine will be hot as hell but the heater core will become cool courtesy of the fan. The engine temp will drop at the needle (the I2 doesn't even have one of those,) the air will become cool that is pumping into the cabin, but you're probably seconds from a blown headgasket or a meltdown, split camshaft (I've had it happen before), etc ...

So, the engine really doesn't give a shit about whatever you're doing in the cabin regarding warmth for the most part. But it is a factor, too.

[Cobb]

I am guessing once it reaches a critical mass, like 177 degrees, its harder to cool the engine down and allows more abuse of ev mode for more mpg. I grew up with heat pumps and hate the luke warm air that comes out and rather wait for HOT air instead. Lastly, if electric water pumps are of any quality I am sure we may see them soon as we have electric power steering. Just think, water pump on demand.


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