Applies to : All Marco Water Boilers

How to Descale Water Tank and Clean Water Level Probes
It is a common occurrence for limescale to build up in the tank of a water boiler. The amount of limescale build up is relative to the water hardness in a particular area.

The most common error indication on a boiler is the Ready light giving two red flashes between pauses, indicating that water can’t be seen in the tank. This can be caused by a number of issues, most commonly, limescale or film build up on the water level probes.
Descaling Procedure:
 Isolate machine from power supply.
 Isolate machine from water supply.
 Drain water from machine.
 Remove all lids.
 Remove as much scale as possible by hand, paying particular attention to level probes (White plastic with steel tab). Be very careful not to damage any attachments.
 Use ScaleKleen, Marco part No. 8000270 or similar. Follow instructions carefully.
 Thoroughly clean and flush the machine before re-use.
 Follow installation and first time operation instructions
NB: Always clean the water level probes after descaling and rinsing the tank.
To Clean Water Level Probes:
 Turn off unit at wall socket or unplug from wall socket
 Remove top cover from boiler
 Remove tank lid from tank
 Identify water level probes – flat metal tabs inside water tank, normally 2 or 3 probes
 Dispense as much water from unit as possible using tap
 Thoroughly clean probes with ScotchBrite or scouring pad
 Replace tank lid and top cover
 Reconnect power to boiler and operate as normal


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