"Dave Liquorice" wrote in message
ll.co.uk...
On Tue, 6 Jul 2010 20:10:37 +0100, dennis@home wrote:

I wonder why they don't have a flat plate with a scraper/de-icing
boot
to remove the ice?

'cause users would get fed up going out every hour or so to scrape
the ice off.

Why would they need to go and do it?

Ice is a pretty good insulator. An iced up heat collector is no
longer in contact with the nice, releatively warm, moving air from
which to extract more heat.

Mechanically removing the ice means you have extracted the latent heat.

True you but once frozen you have extracted that latent heat and you
now have an insulating layer on your collector.

Which is why you need the scraper and/or de-icing boot.