In article ,
Harry Bloomfield wrote:
Tim Downie wrote on 20/08/2009 :
Any tips on cylinder jackets?

Tim

Yes, don't buy one.

Make sort sort of box, which doesn't cover/allows free airflow around
the immersion heater head (if it has one). Make it at least 2" wider
all the way around and fill the space with insulation. Much more
effective than a jacket.

And if you can't do that, buy 2 of the thickest jackets you can get and
overlap them all round the tank, twice.

Gordon