How do I insulate my Laddomat 21 boiler charger?
They talk about using EPP-Insulation which is expanded polypropelyne foam:


  EPP is flexible foam that is used as a packing material for delicate electronic parts.  It is also used in the bumpers of some automobiles.  It is a rubbery material that is light in weight, yet very durable. 


http://www.flyingfoam.com/FoamTypes.html

Based on that, I think you could do quite well with simply buying some basic pipe insulation


and do some creative wrapping of the insulation around the fitting, adhering it with duct tape (not directly to the device but insulation to insulation only).