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From the Archive: Tank Care

Draining Sediment from a Tank Heater

A few litres of cloudy water, drained once a year, can add life to a tank heater and quiet its rumbling.

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Why bother

Minerals in Halton's water settle at the bottom of a tank heater as sediment. It insulates the water from the burner, wastes fuel and makes popping or rumbling noises. Flushing removes some of it.

A workshop with a range of tools
A workshop with a range of tools.

The procedure

  1. Check ownership. If the tank is rented, the rental company may want to handle maintenance.
  2. Turn the heater off. Turn a gas unit’s dial down to its vacation or pilot setting. For electric, flip off its breaker.
  3. Close the cold water inlet valve at the top of the tank.
  4. Connect a garden hose to the drain valve low on the tank, then lead the hose to a basement floor drain or out a door.
  5. Open a hot faucet on the upper floor so air can enter the lines.
  6. Open the drain valve. Be careful: the water may be very hot. Let several litres run until it clears.
  7. Flush with cold water. With the drain open, quickly open the cold inlet to churn up sediment, next let it drain again.
  8. Close the drain, open the inlet, refill. Wait until the hot tap runs steadily before turning the heater back on.

Never fire an electric element or gas burner on an empty tank. Refill completely first.

Keep this kit by the main shut-off

  • Flashlight or headlamp
  • Bucket and old towels
  • Adjustable wrench and slip-joint pliers
  • Flange plunger for toilets, cup plunger for sinks
  • Label on the main valve so anyone can find it

Watch out for

  • Old plastic drain valves can break or fail to reseal. If yours drips after closing, cap it and call.
  • Do not test the temperature and pressure relief valve on an old tank unless you are ready for it to keep dripping.
  • If the water runs rusty for a long time, the tank lining may be failing.

Stop and phone a plumber when

  1. 1A ceiling or wall starts dripping
  2. 2More than one drain backs up at once
  3. 3You smell gas or sewage indoors
  4. 4A valve will not turn or drips when touched

When to call

Phone us when the drain spigot drips afterward, the tank shell is damp, or the heater will not relight. See water heater repair, or if the tank is near the end, gas or electric replacement. Tankless units need descaling instead.

Straight answers to common calls

How often should I flush my tank?

Many makers suggest once a year; check your manual.

Can flushing fix a leaking tank?

No. Once the steel shell itself weeps, the heater has to be swapped out.

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Call (365) 399-5986
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