Geyser making popping or crackling sounds: scale on the element

A geyser that has started to pop, knock or crackle while heating is not about to fail today. It is telling you it will fail this year unless something changes.

What the sound is

Scale has built up on the heating element. Water trapped between the scale and the hot metal flashes to steam and escapes with a pop. The louder and more frequent it is, the thicker the layer.

What it is doing

• The element runs hotter to push heat through the scale, and eventually burns out
• Heating takes longer, so the geyser runs longer and the bill goes up
• Scale falls to the tank bottom, insulates it, and accelerates corrosion there
• The thermostat reads the water, not the element, so it does not know the element is overheating

How long you have

From the first popping to a failed element is typically a season, sometimes two. It is not an emergency. It is a booking.

What descaling involves

Power off at the MCB, tank drained, element removed, scale chipped and dissolved off, tank flushed, anode rod checked while it is open, everything refitted with a new gasket, refilled and tested. About ninety minutes. The geyser heats faster afterwards, noticeably.

Chemical descalers poured in through the outlet do not reach the element properly and can damage the tank lining. Descaling is done with the element out, not from the tap.

Afterwards

Set the thermostat to 55 or lower and put a reminder in for next year. In tricity water, annual is the interval that keeps a geyser quiet.