Scale warnings
The heater tells youit needs a flush.
Three signs that show up long before a heater quits, and all of them come from the same cause.
01
Knocking from the tank
When sediment settles over the element, the water trapped underneath boils and forces its way up through the layer as bubbles. That is the knocking or rumbling you hear from the cylinder while it heats, and it is the first call for a flush.
02
The first draw runs cloudy
Hot water that comes through cloudy or carries white grit and then clears is loose sediment moving off the tank floor. A rusty tinge is a bigger story: the internal protection has been used up and the steel has started to corrode.
03
It takes longer than it did
The tank needs longer to reach the same temperature and nothing about how you use it has changed. Scale on the element blocks heat from reaching the water, so the heater draws power for longer and gives you less back.
Servicing at a glance
What a servicecovers.
Service
Servicing, flushing and repair of water heaters
Included
Draining and flushing, descaling the element, checking the protection rod and the valves
Heaters covered
Central cylinders and the small bathroom heaters
Best time
Before winter, and before the first run after a long break
Hours
Daily, 6:00 in the morning to 12:00 midnight
The service, in order
How the serviceruns.
The same four steps every time, and none of them gets skipped.
We isolate and drain
The power goes off, the cold feed is closed and the drain valve opens until the cylinder is empty. What comes out last tells us how much sediment has collected on the floor.
We flush the floor
With the tank empty we open the cold feed again so the incoming water stirs the sediment and carries it out through the drain. That is repeated until the water leaving runs clear.
We pull and descale the element
The element comes out of its flange and the scale crust is cleaned off the sheath. We also check how much of the protection rod is left, since that rod is what keeps the tank wall from rusting.
We refit and test the valves
The element goes back with a new gasket, the tank is filled and vented, and the safety valve is worked open and shut. Then the power returns and we watch the temperature settle.
Why flushing
Why heaters scaleup in Kuwait.
Kuwaiti water is desalinated and carries calcium and magnesium salts. They stay dissolved while the water is cold and drop out of it when it is heated, and the first surface they settle on is the hottest one inside the cylinder, which is the element sheath. The scale lands exactly on the part whose job is to move heat.
Whatever does not stick to the element falls to the floor of the tank. That layer does two things: it occupies space that used to hold hot water, and it insulates the bottom, so the element has to run longer to reach the same temperature. Less capacity, more power drawn, and an element that tires early.
A service also looks at the parts nobody thinks about. The protection rod inside the tank corrodes in place of the steel and eventually runs out. The flange gasket hardens with heat and starts to weep. The safety valve scales up and can stick shut, which is the worst of the three, because a valve that cannot open protects nothing.
The best time is before the cold sets in, and before switching on any heater that has stood unused for months, such as one in a chalet or a closed up house. Water standing in a still tank changes its taste and its smell, and a flush deals with that. To be straight about it: servicing extends the life of a cylinder, it does not restore a wall that has already corroded.
External links for referenceMinistry of Electricity and Water (electricity and water supply to the building)
Servicing questions
Asked aboutservicing.
Before each winter is the natural point, just before you switch it back on after the summer. If you hear knocking from the tank or the hot water runs short before then, do not wait for the season. Those signs mean the sediment has already earned a flush.
It is worth doing as long as the tank wall is sound. Flushing gives back the capacity the sediment took and lengthens the life of the element. If the cylinder is corroded inside or weeping from its body, a flush will not touch that, and we say so as soon as it is open.
Yes. A small heater is the same idea in a smaller shell: an element, a thermostat and a little tank that scales up the same way. It is easier to reach, and the scale shows sooner because there was not much capacity there to begin with.
Usually it is water that has stood in a tank nobody has used, or a reaction inside the cylinder around the protection rod. Draining, flushing and checking that rod deals with most cases. The giveaway is that the cold water in the same house has no smell at all.
No, leave it to us. Draining has to follow the isolation of the power and the cold feed in order, and opening a drain on a cylinder still full of hot water under pressure causes more trouble than it saves. Switching the heater breaker off is enough.