Water heater problems in Dubai, and what they mean

Dubai is unusually hard on water heaters, for three reasons that compound each other: the water is hard, the ambient temperature is high for much of the year, and in most apartments the tank is sitting in a ceiling void where nobody looks at it until something drips.

The summer paradox

People are often surprised that water heaters fail in summer. It happens for a reason that is obvious once said: in summer the cold feed is not cold.

Water sitting in pipes and roof tanks in Dubai arrives warm. The heater has less work to do, so it cycles differently, and a tank that was coping in February can behave quite differently in July. Plenty of households switch the heater off entirely for a few months — which is sensible, and which is also when a slow leak goes unnoticed because nobody is using it.

Hard water and scale

This is the main culprit.

Dubai water carries a lot of dissolved mineral. Heat it and the mineral comes out of solution and deposits on the hottest surface available — which is the heating element. Scale on an element acts as insulation. The element works harder and hotter to heat the same water, which makes it fail earlier.

The same deposit collects as sediment at the bottom of the tank. That is what causes the popping and rumbling sound people describe: water trapped under sediment boiling and escaping.

What follows from it: a heater that is descaled periodically lasts noticeably longer than one that is not, and a heater that has never been descaled in five years may be beyond saving rather than worth repairing.

What the symptoms usually mean

No hot water at all. Element, thermostat or supply. If the breaker for the heater has tripped, that is a fault rather than an inconvenience — see below.

Hot water that runs out quickly. Either the tank is undersized for what you are asking of it, or sediment has reduced the usable volume, or the thermostat has drifted.

Water that is too hot, or wildly variable. Usually the thermostat.

Rumbling or popping. Sediment. The tank is telling you it needs flushing.

Discoloured or rusty water from hot taps only. The tank’s internal protection has gone and the tank is corroding. This one does not get better, and it is a replacement rather than a repair.

Damp patch on the ceiling under the heater. Stop. See below.

The two things you can safely check

1. The breaker. If there is no hot water at all, look at the distribution board. If the heater’s breaker has tripped, reset it once. If it trips again, leave it off and call. A water heater tripping a breaker repeatedly means current is going where it should not, and that combination — water and a fault to earth — is the one not to experiment with. It is as much an electrical job as a plumbing one.

2. The isolator switch. Many flats have a separate switch for the heater, often outside the bathroom and often knocked off by accident. Worth checking before anything else.

Beyond that, leave it. Water heaters combine mains electricity, pressurised hot water and a heavy tank, usually in an awkward overhead space.

The ceiling stain

If you see a damp patch or a stain on the ceiling below the heater, treat it as urgent.

Tanks rarely burst without warning; they usually seep first. The seep is the warning. A heater that is weeping into a ceiling void will eventually bring part of that ceiling down, and in an apartment the damage frequently ends up in the flat below — which turns a repair into a conversation with a neighbour and an insurer.

Turn the heater off at its isolator, turn off the water feed to it if you can reach the valve, and call. Our plumbing page covers leak tracing and heater work.

Repair or replace

Worth repairing: thermostat, element, a failed valve, scale that has not yet done structural damage.

Worth replacing: a corroding tank, discoloured hot water, a tank that has already leaked, or any unit old enough that you are repairing it for the second time. Past that point repeated repairs cost more than the replacement and you still have an old tank in your ceiling.

Anyone who tells you the answer without looking at the tank is guessing.

Getting more years out of it

• Have it descaled rather than waiting for it to fail.
• Do not set the thermostat higher than you need. Hotter water deposits scale faster, and in a Dubai summer you need less than you think.
• If you switch it off for months, check around and under it when you turn it back on.
• Know where the isolator is, before the day you need it.
• If a tenancy is ending, get it looked at. A heater that fails the week after a new tenant moves in becomes an argument about who was responsible.

Who pays

In a rented property this usually falls to the owner, because a water heater is part of the property rather than something the tenant brought. But it depends on the cause and on what the tenancy contract says — and we have attended plenty where the real cause was something quite different from what was assumed.

What helps either way is documentation: what failed, why, and what it took to put right. That is what turns a disagreement into a decision.

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Suspect yours? Tell us what you are seeing — and if there is a stain on the ceiling, call instead.