I have a project for which I want to use an immersion heater element. I am having a water tank made and need to give the fabrication shop the dimensions of the hole to be drilled in order to accommodate the heating element. Does anyone know the dimensions of the hole?

Thanks Tyke

http://www.ctlimited.co.uk/standard_immersion_heaters.htm

threaded:

Screw in Immersions
These are readily available in 1¼", 1½", 2" and 2¼" in brass and 2¼" BSP in Stainless Steel

2 1/4" seems standard for hot water tanks I think.

you might be able to get a range of flanged ones too.