How does the HVAC system warm up so quickly on cold start?

[Matteo88]

i searched and searched but couldn't find a thread on this.

can anyone explain why the F80/F82 warms up so damn quickly? i have been noticing this more and more since winter hit but last night took the cake.

there's a cold front in and around toronto currently. the wife and i went to a movie last night with the car sitting in -15C to -17C (5F to 1.5F) as the night drew on.

i want to say in less than 2 mins, less time that it took me to get out of the parking lot, it was already blowing heat.

it seems almost physically impossible.

does anyone know if there's something unique engineered here?

as an aside, 2 weeks ago i had it parked outside at a hotel on a -21C (-6F) overnight with lots of wind (windchill of -32C or -27F) and there wasn't the faintest struggle when i started it up. every other car i have owned has struggled to start in these temperatures.

[jailonacs99]

Originally Posted by Matteo88

i searched and searched but couldn't find a thread on this.

can anyone explain why the F80/F82 warms up so damn quickly? i have been noticing this more and more since winter hit but last night took the cake.

there's a cold front in and around toronto currently. the wife and i went to a movie last night with the car sitting in -15C to -17C (5F to 1.5F) as the night drew on.

i want to say in less than 2 mins, less time that it took me to get out of the parking lot, it was already blowing heat.

it seems almost physically impossible.

does anyone know if there's something unique engineered here?

as an aside, 2 weeks ago i had it parked outside at a hotel on a -21C (-6F) overnight with lots of wind (windchill of -32C or -27F) and there wasn't the faintest struggle when i started it up. every other car i have owned has struggled to start in these temperatures.

I'm not a mechanic or an engineer, but just speculating; this is a big engine and the turbos spool at a very low RPM. BMW recommends driving from cold start as the most efficient and fastest way to warm the engine, so I imagine that at cold start the one thing the car is doing less of is running the radiators and coolant. The car's just not restricting as much the massive amount of heat it normally puts out.

[instarand]

Originally Posted by Matteo88

i searched and searched but couldn't find a thread on this.

can anyone explain why the F80/F82 warms up so damn quickly? i have been noticing this more and more since winter hit but last night took the cake.

there's a cold front in and around toronto currently. the wife and i went to a movie last night with the car sitting in -15C to -17C (5F to 1.5F) as the night drew on.

i want to say in less than 2 mins, less time that it took me to get out of the parking lot, it was already blowing heat.

it seems almost physically impossible.

does anyone know if there's something unique engineered here?

as an aside, 2 weeks ago i had it parked outside at a hotel on a -21C (-6F) overnight with lots of wind (windchill of -32C or -27F) and there wasn't the faintest struggle when i started it up. every other car i have owned has struggled to start in these temperatures.

Blowing warm air is different than the car getting up to temperature. My F80 usually take a good 5-10 minutes of driving before the oil reaches operating temp. However, it'll blown warm air almost immediately. Keep an eye on the oil temp needle next time and watch how long it takes to make it even a quarter of the way up.

[joooiiiiii]

Really? Weird, my A/C doesnt blow hot air right away, maybe something is wrong with my car. I literally start it up and put it in D or R out the parking lot--usually takes a few minutes though...

[Shadowmak]

As far as I know every F3X and F8X has an electric blow by heater included that heats up the passengers room very fast... The heat doesnt come from the engine...

[jailonacs99]

Oh, I thought OP was talking about the actual engine temp, not just the blowers. Well...that's what they're designed to do, like the heated seats and steering wheel. If they don't do it while everything is freezing cold, what's the point?

It's also going to be relative; the colder it is inside and out, the more even slightly warmer temps will feel by comparison.

[CanAutM3]

The answer is simple: the S55 has a very well engineered cooling system.

There are many different loops in the cooling system that are driven by their own individual electrical pumps, so the engine ECU can select where and how much of the coolant flows. On start-up, the engine coolant is only run through the cabin heat exchanger (item-10 on the chart below) by having the thermostat (item-6) closed and the cabin heating pump (item-11) running, which is how it can provide heat so fast.

[CanAutM3]

Originally Posted by Shadowmak

As far as I know every F3X and F8X has an electric blow by heater included that heats up the passengers room very fast... The heat doesnt come from the engine...

No it doesn't have an electrical heater and the heat does come from the engine. The cabin heating has it's own electrical driven coolant pump though.

[jimmydick]

Originally Posted by CanAutM3

The answer is simple: the S55 has a very well engineered cooling system.

There are many different loops in the cooling system that are driven by their own individual electrical pumps, so the engine ECU can select where and how much of the coolant flows. On start-up, the engine coolant is only run through the cabin heat exchanger (item-10 on the chart below) by having the thermostat (item-6) closed and the cabin heating pump (item-11) running, which is how it can provide heat so fast.

Great post

[robbo mcs]

The start up process is designed to run the engine and exhausts as hot as possible initially, so as to try and and get heat into the catalytic converters ASAP. Part of this is running the engine lean initially. So the engine does generate significant heat in the initial startup

[JoeFromPA]

I'll just second: fastest in cabin heat I've ever gotten from a vehicle.

Between that and the hottest seat heaters I've ever had, I can get pretty damn toasty pretty fast in the f80.

[gatorfast]

Its science bro

[minn19]

It is one of the reasons the M3/4 are/have been one of my favorite winter vehicles of all time. I left for work early this AM and it was a coupe of degrees below zero. Within a mile or two the seat/steering wheel are nice and toasty, plus like others have mentioned it starts blowing warm air pretty quickly.

[clubracer6]

I'm still shopping, but sounds like a great feature regardless of how is happens!

[Nicky_do_it]

Originally Posted by joooiiiiii

Really? Weird, my A/C doesnt blow hot air right away, maybe something is wrong with my car. I literally start it up and put it in D or R out the parking lot--usually takes a few minutes though...

+1 Mine doesn’t seem to warm up quickly.

[G35POPPEDMYCHERRY]

Originally Posted by jimmydick

Great post

I love when he nerds out lol.

[CanAutM3]

Originally Posted by G35POPPEDMYCHERRY

I love when he nerds out lol.

[EricSMG]

The E46 M3 is even quicker, if you can believe that. It blows warm air within seconds of start up. It also reaches full operating temp within about 3 minutes of driving. Remarkable.