Auxilliary heater

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GrayB

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Has anyone got a feeling for how much the auxilliary heater on a TDI affects the fuel consumption? My other half keeps the Econ button switched on all the time, in the interests of economy - which is fair enough on a short journey, when the Aux heater doesn't have time to do anything. I have noticed that the water temp gauge seems to climb faster when the Aux heater is on, so perhaps by getting the engine up to temperature faster it will actually aid fuel economy [?];)
 
Presumably it depends on the temp outside, if it is 30 degrees probably not as much as if it is freezing, it must be significant or they would not fit it.
 
The Aux heater only works at temperatures below 5 degrees anyway. So unless you live up a mountain in Scotland it rarely gets used surely?!! Not enough to save more than a fiver a year in fuel anyways in my mind...

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[img=left]http://img.villagephotos.com/p/2002-2/11882/a2andme2.gif[/img=left]
2001 A2 TDI SE Crystal Blue with Open Sky, 6CD Symphony II, BOSE upgrade, DIS and HALF a winterpack!

iPAQ 3970 with Sat-Nav sleeve, rear cupholders, luggage net and floppy wiper!

http://www.a2oc.net/pic_show.asp?picid=1572&type=1 On www.A2OC.net pictures UK160 to UK183
 
I thought the Aux heater kicks in at below 5 degrees to aid the interior to warm up quicker. Hence the Aux heater is more effective for shorter journeys when the engine does not have time to get up to temp.

Shaf

1. Mar 2001 TDi 75 SE, Silver, black/grey interior, climate, winter pack.
2. Nov 2002 TDi 75 Sport, Silver,black/grey interior,climate.
3. Jun 2004 TDi 90 Sport, Silver, wrong interior (black/black), climate, front fogs.
4. Sep 2004 TDi 90 Sport, Silver, black/grey interior, climate, leather/alcantara, front fogs. HID Xenon's.
 
[37]
There are two aux heater types fitted to the A2. The 'early' type is a Webasto Fuel burning device which does use fuel and can increase specific consumtion.
It kicks in at 7c.
the 'very much later' type is an electric PTC device which does not use fuel directly obviously but places load on the alternator. This uses much less fuel
It too triggers at 7c.
Mine was a Webasto and if you turned it off once the cabin and engine were warm it had little effect on consumption BUT if, as I had the misfortune to do, you leave it on on a long journey with low outside temps the consumption climbs quite markedly. About 8 -10 mpg.
The A3 has a PTC rated at 1 kw and appears to have minimum effect on economy. This is why the early Webastos were replaced. I still miss the whine and the separate exhaust on a cold morning though - and the attendand cleaning cycle after the car is parked.
[7][7][7][7]

NEVER attempt a battle of wits with an unarmed man.
A2 1.4 SE TDI replaced with A3 2.0TDI DSG, the transmission of the future - today.
 
Mine has the sound like a fan heater when you stand outside the car - so I expect it is the Webasto (2001 car). Just lately, there have been days where the temperature hasn't got over 5c all day - in the wilds of East Sussex / Kent! So, the heater was on all the time... Thanks for the thorough answer Maersk!
 
Top Tip - If you use the 'econ' all the time the compressor on the air con is turned off. Whilst it doesn't work below 5 deg C it will at all other times if you are not on econ.

If it does not get regular prolonged use it will cause the joints to seep the air con gas and the pump will ultimately have a short life. If you want a £700 bill for 3 years of motoring on econ then 'crack on'. I leave the climate on AUTO all the time and still get 60+ mpg of mixed driving.[24]

I used the econ a lot on my old A4 and guess what just out of warranty the compressor broke - Verdict - not enough auto use. [29]Luckily for me Audi gave me a good will gesture and I only paid £250 for the compressor and they fitted it for free.

I have the Webasto and it is FANTASTIC. At 60mpg I dont worry myself with fuel economy as within 5 mins of leaving home in sub 5 deg temp the car interior is fully warmed up.

Regards - The Foghorn

2001 TDI SE Atantic Blue, Open Sky, 16" 6 spoke alloys, Satellite cloth & space box system. The "Dogs Twitchers"
 
It costs me something between 50 and 100 km's on a full tank. It's freezing here the past week so the thing is on the whole time.
But I must confess that my timer switches the heater on 10 minutes before I start it, to defrost the windows, so that also consumes fuel.


Dennis de Held

Amulet Red 1.4 Tdi
 
Maersk - Webasto Auxilliary heater kicks in at 5 degs C, but IMHO 7-8 degs C would be better - seeing that temp say 5.5 deg C and then having no heat is a real bummer!! I read the fuel consumption somewhere but can't remember the exact figure, but one litre of fuel provides many hours of heater use.
 
Have now filled up after the cold spell and, while it may not be all down to using the auxilliary heater, the mpg for the tank full fell to 48 from the average over the last 4 tank fulls of 54mpg. Have decided to use the the heater but to turn it off after the warmth starts coming through - a 'brief' press of the Econ button according to the handbook. And yes, I know about the danger of not running the compressor regularly - we bought a Mercedes from someone who hadn't. £1100 later....
 
[37]
Intersetingly my A" cut in at 7 and the A3 is the same..7 as per hand book. A UK setting via VAG - Com?

7 is much more reasonable on these cold mornings althought the heated seats tend to disguise heater shortfall!


NEVER attempt a battle of wits with an unarmed man.
A2 1.4 SE TDI replaced with A3 2.0TDI DSG, the transmission of the future - today.
 
[7]
Heated erm, leather.
[7]

NEVER attempt a battle of wits with an unarmed man.
A2 1.4 SE TDI replaced with A3 2.0TDI DSG, the transmission of the future - today.
 
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