you have to wait for the engine to get warm,so that te collent gets warm .
so the best way is to set the blower to the lowest setting put the heater control to the temp. you want and drive off!
It is worthwhile to set the air lever on “recirc”, so that you are heating up the air that is in the car, not cold outside air.
I say, Crank the windows down and the AC up. This won't warm the car but after the hypothermia sets in, She won't be arguing with you. HOWEVER-It has been my experience that the vehicle heats up best when you set the temp as high as possible, BUT- run the blower at half speed (not at full).This (Stanistan’s post) is a good take on the situation, but can be expanded by realizing these three points:
- the heat generating system is more complex than a simple vent emtting hot air.
- when we refer the the “temperature of the car” we are really refering to the “temperature of the driver”
- there is a heat conduction circuit in the system with nodes terminated in non-zero thermal mass objects
re: #1, Modern car heaters usually run the heated air thru the air conditioning evaporator so that the air emitting from the vents is controlled to a constant temperature by first heating it up then cooling it down. This removes moisture. The effort from the cooling part of the system is usually fixed - not controlled by the heater setting. However, at the very start of the heating process (engine just started), the air conditioning will start cooling the air far quicker than the engine will generate the heated fluid for heating the air. Thus, in the very beginning, most heater systems actually produce colder air than ambient (albeit de-humidified). This gets corrected as heated fluid becomes available, but common sense would say the first tactic to heating the car up in the least time would first involve leaving the heater off for some time - to be determined empirically. For my Ford Ranger, this time is about 20 seconds while the car is running at 30 to 40 mph.
Re #2: We have to remember that the temperature we are seeking to raise is not the temperature of the cars interior but the temperature sensed by the driver or passenger. The heater is measuring the system temperature at a location other than the driver - typically close to the air inlet which is only a rough measure of the cabin temperature and a worse measure of the driver’s temperature. The driver is usually insulated from the circuit by a coat, pants etc, assuming he/she is not driving in the winter nude). This leads to topic #3…
Re #3: The walls, floor, windshield of the car are removing heat from the “system”; these have finite thermal mass. The heater is injecting heat into the system at a fixed temperature. And the driver is insulated from the warmer sir by a coat. The “system” is a circuit of a heat source (the heater) and a heat sink (the walls, etc.) with the driver connected thru a heat insulator. This is analogous to a electrical circuit.
It should now be obvious to the reader that if a cetain temperature is desired at the skin of the driver, the temperature emitted by the heater must be something greater to minimize the time to reach a steady state. This requires changing the system from a “bang-bang” servo to a “proportional control” servo with the system sensor being the skin of the driver. Initially, higher than final heat should be applied compensating for the finite heat flow between the nodes of this circuit and the heat lost into the “heat sinks”.
Here’s the bottom line:
For minimum time to reach a comfortable temperature for the driver or passenger:
- upon starting the car, leaver the heater off for a short duration (about 15 to 30 seconds) to avoid receiving the refrigerated, dehumidified air.
- at this time, the heater temperature should be set to the maximum (and vents pointed away from uninsualted driver / passenger surfaces which would be irritated by the high heat (such as the face).
- as the driver / passenger senses a comfortable temperature being reached at his/her skin, the temperature set point should be gradually reduced to normal. Gradual reduction is called for because the heat sinks in the system are still absorbing heat dropping the set point in one step would cause a commensurate step change in the driver/passenger’s temperature.
It is a subtlety, to be sure, to recognize that heat from the heater doesn’t flow instantly to all regions of the car, but people’s common sense has naturally lead to tweaking the heater setting for decades because it is simply more comfortable. Then “experts” such as Tom&Ray poo-poo this and righteously lecture about the fixed heating effort from the heater and disregard the reality of a heater system with cooling facilities and a heat circuit with a finite flow of heat and thermal mass. In other words, they dismissed applying the details of the thermodynamic education they must have received at MIT in favor of a righteous, anecdotal and expeditious explanation, no doubt to get them to the cofee and doughnut break faster.
Very good. That is exactly what you get with the high end model like a Maybach / Bentley, etc.(seat heaters would also assist the system)
T&R have a matter of seconds; well, maybe a couple minutes over the phone; on the air; to come to a conclusion.
This question cannot be answered with any accuracy without knowing the car make, model and year. The reason being, they all have differing levels of control and sophistication in that control. For example, the higher end cars have automatic climate controls. They sample the cabin air and use sophisticated software servo algorithms to attain and maintain the heat setting as quickly as possible. In those systems, you can set the desired temperature to 72 and the system will begin mixing in heater air as soon as the engine begins to warm. It will select a fan speed that maximizes heat transfer without blowing too hard to upset the occupants due to drafts (even though heat can be transferred almost as soon as the engine idle settles down). The control will adjust the blend door for maximum heat and continue to taper it off to attain the desired temp as quickly as possible without significant overshoot.
On a manual system or one that is not as sophisticated, the operator can achieve similar results by setting the heat hotter than the desired temp and performing the regulation manually. It is always faster to have the hottest possible incoming air mixing with the cold cabin air. Simple averaging…
I think to get the passenger hot, fast, you need to give her a couple of drinks and maybe some jewelry . . . what? . . . “passenger compartment?” . . . never mind.
Just a second thought. [b] Hubby is car smart and wife dumb. [/b] It will not hurt to turn it up so do it!The wife’s right: set to maximum until comfortable; then set to desired temp. Here’s why. When you set the temperature, a computer takes that imput, along with measured ambient temp, to adjust the % of heated air introduced to the cabin. Effectively, you’re controlling the temperature the same way with climate control as you would with a mechanical system–only indirectly vs. directly.
If you “peg” the heat, you know darn straight that you’ll get maximum-performance heating. Thus, the “set-n-forget” crowd can–at best–equal your results, not beat them. Considering the posts in this thread, even determining with any certainty if everything’s equal requires graduate-level engineering classes, which is way, way too much effort just to duplicate the results of the “pegged” crowd. The only downside I see is that, because you’re probably not as accurate as the thermometer in the car, you might wind up overshooting the mark a bit.
Secondly, I doubt you’ll actually get max performance. Consider a revised question: what’s the fastest way to get form 71F to 72F? I doubt the car would crank the heater until exactly 72.000F. After all, the heating requirements to miantain equilibrium will change as speed, cloud cover, outside temperature, etc. changes–the computer’s always slightly behind the curve, and I’m guessing starts varying the temperature GRADUALLY as it “brackets” the set temperature. I think posters are confusing home heat (where intermittant heat is supplied when temp drops below the lower parameter and maintained until it rises above the maximum parameter) with continuous automotive heat output. Try it yourself–stabilize at 71, then increase the setting to 72 and see if you get “full blast” heat.
Finally, a brief rant on climate control. Living in this technical age, people seem to embrace high-tech for its own sake. I think I probably need to adjust the heating temp in a HVAC car just as much as in my “dumb” car, because 68 might feel great in the sun, but too cold when I make a turn and am back in the shade. In exchange for the few times I might not need to adjust the heat, I am no longer capable of directly controlling the temp of the air coming out of the vents. Plus I have to pay more to acquire and maintain it. (I’d love to see a time-and-motion study comparing the average amount of time saved over the course of a car’s life vs. the added cost of HAVC and do a cost/hour calculation.)
Can any climate-control devotees set me right about its importance?
So in mathematical terms you’re suggesting delaying the starting point of that exponential curve in exchange for a faster-rising curve once you do turn on the heat. I would guess that, at best, the desired equilibrium could be reached at about the same time by doing that, but meanwhile the occupants are freezing their endpoints off, so I wouldn’t do that. In fact I don’t do that - I crank the heat lever to max and leave it there until I start getting hot! Occam’s Razor - the simplest solution is probably the best solution.
I agree the simplest solution is best, so I just keep my paws of the climate control and let it do it’s thing. The system will normally sense the temperature and do what’s best to heat the cabin as quickly as possible. We all paid for these fancy climate control systems, just let them work as designed.
It depends on which kind of controls you have.
If you have the kind with a real thermostat, it will take the same time either way.
If you have the kind with just an adjustable hot-water valve, the higher setting heats the car faster, but overshoots.
Some electronic controls have sensors to detect the radiant energy load. I guess that yours does not.
Proportional controls will only raise the temp faster than snap-action when getting relatively close to the set point. As others have already pointed out, there are lots of other issues, associated with comfort, in addition to the actual air temp. Radiant energy has been specifically ignored in the discussion so far, though maybe tangentially addressed.
Some of this is right, but you need some tweaking. All of the cars I know of, modern or not, cool the air in the AC evaporator and then heat it up when the AC is activated at all. This is in the Defrost or AC, or mix positions alone, not the floor heat settings. The latter is what is generally used in very cold conditions. The reason for this is that cooling and then heating is a much more effective way to dehumidify the air under conditions when it is useful to do that. The temperature is generally controlled by heater doors that direct air across the heater core, more or less. In older vehicles there were valves that controlled water flow through the core, but this has been used less since AC has become standard equipment.
Sub-cooling and reheating is the way most commercial buildings control humidity. I do it in my home sometimes as well.
In addition, under conditions where one would be concerned with how fast the vehicle is warming up, the AC will compressor will not be on for a significant period because the controls on the system will not allow it. For example the high pressure switch in some systems will not allow the compressor to cycle on unless the evaporator is warm enough to vaporize the refrigerant.
Most cars today have blend doors that control air flow over the heater core. There is no valve.
The best way to warm up the car, to me, is to not use the heat at all until you have reached normal operating temperature then turn the heat on full. The more water you circulate through the heater core and exchange with the cold air the longer it will take for your car to warm up and the thermostat to open. The goal is to get the car running at the proper temp, then apply the heat. The only exception is if you have to defrost/defog some windows. I never understood folks I rode with that when we jump in there cold car, they turn the “heat” and fan on and blow cold air all over us.
If you have something like a http://www.scangauge.com/ you can easily watch the water temp rise as you drive. Note that on a really cold morning, when you do dump the heat on full you can watch the water temp fall quite a few degrees.
Dennis
If you find the best way, you might save how much time? Not enough. Heated seats help while you’re waiting.