Bus Heating Question

[Peter1805]

Okay, here is a simple question for someone:

How do the heaters work on modern buses, such as, for example, a Scania K230UB Custom Coaches "CB60 Evo II" ??

Specifically:

(1) do they rely on engine heat, or do they operate independently of engine heat? ; and

(2) do rev levels have anything to do with it - eg, would low rev level affect it? ; and

(3) where does the demister source its heat from?

Thanks in advance.

Cheers,

Peter

[Two-Way]

From the engine coolant. You will see coolant hoses running up to the AC and to the dash for heating. Revs do nothing....might warm the engine up a bit quicker maybe.

[boronia]

Some buses will have heater modules on the floor under the seats or along the sill line, usually with fans for distributing hot air.

These work off coolant too.

[Peter1805]

Thanks for answers so far.. much appreciated.

[The Inventor]

I would think all heating in buses get the heat from the engine through the coolant. As the others have already pointed out.
Engine speed doesnt necessarily mean more heat, but more the amout of throttle/accelerator.
More accelerator=more heat produced which I think would rise with engine speed due to friction.
I do know that CNG and petrol engines run hotter than diesels do which in turn would affect the heating.

Hope this helps answer some of your questions.

[Peter1805]

Yes, thanks for that..
Makes sense, but I thought there may be some other mechanism involved as well.

[boronia]

Some buses may have reverse cycle air conditioning, which will provide all the heat necessary.

[Peter1805]

Thanks for all your answers.

I have also now located another thread on this board which provides many of the answers:

viewtopic.php?f=2&t=42831&hilit=heating&start=25

[Derwent]

Every CB60 I've seen/ridden on/driven has had full climate control aircon.
I believe this is generally reverse cycle so is powered by a belt driven compressor on the engine.
Older buses with heaters under the seats are engine coolant powered.
The ones on my usual bus have an annoying habit of springing a leak leaving a nice puddle of coolant on the floor.....had to get it fixed half a dozen times in a year.

[Daz]

RPM vs speed is what will make them warm up faster. Ie a high power setting (motor generating energy which is mostly released as heat) and low RPM (water pump not spinning as fast so slower circulating coolant gets hotter, also fan speed on older direct drive fan vehicles) and low speed (less cool air being ducted through the radiator and around the engine).

All of the vehicles I've had anything to do with have had demisters, floor heaters and roof a/c heated by coolant. Generally speaking there is an auxiliary electric lift pump to get hot coolant to the roof quickly and help the cycle.

Demisters are often turned off in older buses because the heat exchangers are hopeless and generally leak, the hoses crack and chuck it in, or blokes turn them on flat out in the freezing cold and make a two piece screen on a vehicle never built for it.

Daz