On Wednesday, 3 December 2014 18:58:50 UTC, Clive George wrote:
On 03/12/2014 13:05, fred wrote:

What ? My description of a large lump of aluminium heated by the engine and which BMW UK say is correct ? Where is the fuel burning cabin heater coming from ?

I'd trust the BMW sales bod to know that such a device was sold, however
I'd not trust them to know what it's made of.

The large lump of aluminium is wrong according to what I've read. Latent
heat store needs to involve a phase change (that's what the 'Latent' bit
is), and you don't want to be doing that with Al :-)

The reason you use something with a phase change rather than just a hot
something is that you can store more energy with the former.

It's a box containing (I think) a sodium acetate solution, connected to
the cooling system, presumably with some control gear to use the heat.

So I reckon you were right in that there was an option. But it was never
a large lump of Al.

And the auxiliary heating does sound a lot more like it's going to be a
fuel burning heater. The alternative is that it's an electric one, but
taking a lot of power out of your battery prior to starting when it's
very cold is generally regarded as a poor move.

(and no, I'm neither a BMW owner nor a 'wannabe' - I just know how to
find things on t'internet)

Well I didn't ask a BMW sales bod. but this Wiki page

http://en.wikipedia.org/wiki/Talk%3A...ries_%28E39%29

has some interesting comments on BMW latent heat devices. There is one comment about using sand to store engine heat to be released later. This is closer to what I remember. After all electric storage heaters use bricks or concrete blocks to store heat. These obviously would be too heavy for use in a car, hence possibly, the concept of using aluminium.

And for those still doubting the existence of these item 538 on this options list shows them

http://www.bimmerforums.com/forum/sh...1#post19880531

Bimmerforums? Hmm. Most be a more erudite forum than that previously mentioned.