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)