Water heating element – clip, power – 2.5 kW

Scale is what kills water heating elements. A crust of salts on the tube acts as a blanket: the element takes longer to heat, overheats inside and eventually burns out. Pull it once a season and clean it; the stainless sheath takes that without complaint.

This one is rated at 2.5 kW. The 10 mm tube is folded like a paper clip and reaches 22 cm into the tank, give or take 5%, so the tank needs at least that depth. Fittings are 14 or 16 mm in diameter, set 60 mm apart on centres.

For a medium tank, 2.5 kW gives a fair trade between heating time and load on the supply.